Honda CX500 & GL500 Forum

Search Sort Posts:  Oldest to newest Newest to oldest

03-02-2010, 2:41 AM Don in Oz Joined on 03-10-2006 Melbourne, Australia Posts 546 Re: cx 500t engine runs 3 seconds then shuts off OK - you're back to "square one" again, now. Don. GL500I, CX500TC (2), CX500EC (2), 1982 CX500C. GL1000, 1976 CB550F, CT110 (2), XL125S (2), 1973 CB175K6. Kwaka Z250C1 (2). Suzuki GS450SX, DR250SJ, GS125ESD.    Report

03-02-2010, 4:52 AM showkey Joined on 03-02-2007 Northern IL Posts 70 Re: cx 500t engine runs 3 seconds then shuts off Glider: Does the bike run perfect with the Black/Brown grounded? By perfect I mean no codes, full power, no missing, smooth idle etc. CX500T 1982 (3) Transalp 1989 GL1100 1983 XL250R 1987 NT650 1988 TRX250 1986 CT90 1972 C70 1981 XR250R 1994    Report

03-02-2010, 6:00 AM George in Indiana Joined on 03-03-2006 Posts 954 Re: cx 500t engine runs 3 seconds then shuts off Once again, have you tried to jumper out the switched side of the main relay? What if there is a break somewhere in the black wire that leads from the main relay to the fuel pump relay and then to the ECU? The connection should be ok from the main relay to the fuel pump relay because it gets 12 volts for the 3 second run. But what if the branch from the fuel pump relay to the ECU is open? It's possible the ECU needs to see 12 volts on the black wire to know things are ok and in turn it grounds the coil side of the fuel pump relay allowing the bike to run? If the bike runs with the main relay jumpered that would at least narrow things down a bit. CX500 TURBO CX650 TURBO '04 GSX1300R Hayabusa    Report

03-02-2010, 8:18 AM showkey Joined on 03-02-2007 Northern IL Posts 70 Re: cx 500t engine runs 3 seconds then shuts off I was looking at the 650T shop manual last night, looking for the inputs needed to turn the fuel pump on, it makes a reference to the 3 second pump running with key on. The reference is the 3 second timing is control by the ECU by controling ground to the black/brown. There is real absense of info on the fuel control side. That's why I was asking for a confirmation tha the bike runns "perfect". If it does not run perfect that would make a place to start looking, like checking the resistance of the injectors and wiring, if they have a problem the book does say fuel pump shut down will occur. CX500T 1982 (3) Transalp 1989 GL1100 1983 XL250R 1987 NT650 1988 TRX250 1986 CT90 1972 C70 1981 XR250R 1994    Report

03-03-2010, 6:45 PM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off Square on it is Oz....my doubts were confirmed that the tip over sensor was the problem shutting off the engine.  The tip over sensor can be ruled out as I checked it against a good unit and there is no difference in my symptom of the "runs three seconds and shuts off".  So back to shop manual... at page 24-4 is the troubleshooting chart.  everything checks our properly on both relays and the voltage to the ECU.  All that is good... I have had the ECU from this machine operated in on another 82 Turbo and I can say that the ECU is known to be good.  I know I get power up to the ECU on the br/bl wire after it passes through the fuel pump relay... I am  confident the main and fuel pump relays are sound and performing properly... So like you say Oz.. I am back to square one..    Report

03-03-2010, 6:56 PM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off The engine does run well with with auxillary voltage supplied to the fuel pump.  But that is a good idea to check the resistance at the fuel injectors... thanks for your input Showkey.  Still plugging away.  Dan    Report

03-03-2010, 7:10 PM George in Indiana Joined on 03-03-2006 Posts 954 Re: cx 500t engine runs 3 seconds then shuts off The black/brown wire is a ground from the ECU, you should have no power on it. The black wire from the fuel pump relay should feed 12 volts to the ECU. The ECU may be looking for 12 volts at that pin in order to complete the ground circuit on the black/brown wire. There's not much left. CX500 TURBO CX650 TURBO '04 GSX1300R Hayabusa    Report

03-03-2010, 7:38 PM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off Hello George....if I get power to the fuel pump relay then the main relay is doing its job correct?  I get 12volts up to the ECU from the fuel pump relay and get 12Volts across terminals 1 AND 2.  ........Terminal 1 is the br/bl wire from the fuel pump and 2 is the ground wire back to the coil side of the fuel pump relay I think...  .. So that all seems correct.  Can you figure out what I could be overlooking.  You mention the black wire running from the main relay to the fuel pump relay I get about 10 ohms resistance there as I suspect the ECU offers up some resistance there... Ditto for the black wire from the fuel pump relay to ground....    Report

03-03-2010, 8:06 PM George in Indiana Joined on 03-03-2006 Posts 954 Re: cx 500t engine runs 3 seconds then shuts off bl/br should be the ground back to the coil side of the fuel pump relay. When the main relay closes, 12 volts should feed off the black wire from the main relay then branch to the fuel pump relay and then to the ECU (a few other things too like the fan). We know 12 volts makes it to the fuel pump relay because it runs 3 seconds. It's possible that if the ECU doesn't see 12 volts at that pin, it won't ground the bl/br wire? When you put one meter lead to the metal frame of the bike and the positive lead on the BLACK wire off the MAIN relay, do you get 12 volts when the ignition is turned on? When you start the bike and it runs for a few seconds, does that 12 volts stay there? If so follow that black wire to the fuel pump relay and then all the way back to the ECU and make sure 12 volts is staying on there. The injector theory is a good one and I do recall reading that a faulty injector is one of the few things that will shut an engine down. However, the ECU should come up with an injector fault code...actually it's smart enough to tell you if it's the left or right injector that's faulty. CX500 TURBO CX650 TURBO '04 GSX1300R Hayabusa    Report

03-04-2010, 5:09 AM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off Hello George.. about the br/bl wire coming off the fuel relay... Here are the readings I get sequence.... ignition switch on.... no voltage for 3 seconds.... then 12volts continuous ..... meter into brown black pin of the fuel relay and grounded to the frame... I get the same 12 volt reading at the #32 pin connect on the ECU itself... I also get no fault codes.   BTW if I disconnect the tip over sensor the 3 second initial power to the fuel pump is interrupted. Plug it back in and then I get power to the fuel pump so that tells me the tip over switch is operating and not causing the power to the fuel pump to cease flowing. Somthing else is causing that and that somthing is the  problem... Dan    Report

03-04-2010, 5:51 AM George in Indiana Joined on 03-03-2006 Posts 954 Re: cx 500t engine runs 3 seconds then shuts off The bl/br wire sounds fine. The 3 seconds you see voltage disappear is when the ECU sends that wire to ground which completes the circuit for the fuel pump relay coil. The 12 volts you see on the bl/br wire after the 3 seconds should be nothing more than the 12 volts feeding through the relay coil windings. The black wire on the coil side of the fuel pump relay is the one I would be concerned with. When you do the same test you did above, do you always have 12 volts on that black wire to FRAME ground? And that includes the 12 volts staying there even when you start the bike for 3 seconds and it dies out. If the 12 volts isn't getting knocked out in that direction (main relay, ignition circuit ect.) you need to follow that black wire to the ECU and confirm 12 volts is making it up there and staying on. You'll probably need to trace that black wire from the fuel pump relay to the ECU. The schematic shows something like 1.19 which may mean there are 19 black wires? I don't have a schematic with me at the moment, but I don't believe it gave a pin number for that exact wire. CX500 TURBO CX650 TURBO '04 GSX1300R Hayabusa    Report

03-04-2010, 6:23 AM Pim206Gti Joined on 11-26-2009 Netherlands, Europe Posts 71 Re: cx 500t engine runs 3 seconds then shuts off I started looking into the service manual of the Honda Goldwing GL1200l. This bike has almost the same fuel injection system. Wat is interesting is the troubleshooting flow diagram on the fuel pump. The last step is to check if the ECU gets the signal from the starter button. If this doesn't happen the fuel pump won't start. The exact text in the manual : Wiring : disconnect ECU coupler. Measure voltage between terminals 30 (+) and 2 (-). Battery voltage should appear when ignition switch is ON and starter button is pushed. If no voltage is detected then check : open circuit Y/R wire  or Poor contact at 13P black coupler on rear fender This step is not mentioned in the Honda Turbo manual but this one is from 1982 and the GL1200L from 1985. So maybe these problems started after a few years of service on this EFI system. This fault doesn't trip the ECU into fault mode because it's just waiting for the signal, which never comes............... Strange is that the bike runs when you power the fuelpump directly, but it is possible that the Honda engineers never thought about this. If you check the wiring diagram from the Turbo you see also the Y/R ( yellow-red) wire . The 13P black coupler is on the turbo the 6P black coupler mounted under the instrument cluster. So apparantly the starter switch is the signal to start up the fuel pump after the initial 3 second after ignition switch is turned on. Hope this helps,  Pim Honda CBX1000 A ( exploded in my garage ) Honda CX500 Turbo ( summer fun ) Honda CB450S ( cheap - winter fun ) Golden boomerang wheels rock ............    Report

03-04-2010, 6:53 AM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off Hello Pim... interesting that you mention the starter "red" button... because I can tap tap tap the button to keep the engine running... signal obviously goes to the starter motor but maybe not to the ECU ...... hummmm .... that is a fine bit of troubleshooting... I will check that for sure and get back with you... I think the easiest way would be to remove and replace the red start switch (button) and see what happens... Great idea.. i shall go check it out THANK YOU. Dan    Report

03-04-2010, 7:18 AM Pim206Gti Joined on 11-26-2009 Netherlands, Europe Posts 71 Re: cx 500t engine runs 3 seconds then shuts off Good luck. I made a mistake with the : 6P black coupler mounted under the instrument cluster. This is not the coupler. The wiring diagram mentiones : 6P (mini) (Bl) . So this coupler must be under the sidepanel were all the sensor connectors are. On page 11 of the maintenance manual you can see on the lower righthand corner the Boost indicator M6P Black Coupler. The must made a mistake in the description, I believe...... because there isn't a seperate connector for the boost indicator. I don't think it's the starter button because the starter motor works. Just follow the manual check if the signal from the starter button is getting to the ECU. Remove the connector from the ECU and check if you get  a signal on pin 30. Pim Honda CBX1000 A ( exploded in my garage ) Honda CX500 Turbo ( summer fun ) Honda CB450S ( cheap - winter fun ) Golden boomerang wheels rock ............    Report

03-04-2010, 8:06 AM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off Hello Pim again... I do get 12volts at the ECU on pin #30 when I press in the Red Start Button    The signal (voltage) is getting to both the starter motor and the ECU.   That was a good thought though...got to be somthing else though don't you think? D    Report

03-04-2010, 8:31 AM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off Hello again George...... Will be checking the injectors today....maybe if they are marginal then they are signaling the CPU to shut down... great thought ... I will get back to you on this one ...see it the injectors are the problem though they both "click" when I turn the ignition on.  Dan    Report

03-04-2010, 12:33 PM showkey Joined on 03-02-2007 Northern IL Posts 70 Re: cx 500t engine runs 3 seconds then shuts off My bike is in storage......but it would be great to measure the voltage on the BL/BR on known good bike while its running.........I would suspect it should be 0 or near 0 volts. Just to double check we are on the right track. Every thing is pointing to ground of the BL/BR is not getting through the ECU. For the injector theory to be the cause they have to marginal for the bike to run good hot wired but "bad enough" to cause the ECU to shut down the pump.....??????? There still could be another input causing the pump to shut down....lets look at that GL1200I pump circuit and troubleshooting tree fot more hints. When checking the injector and wires for the injectors be sure to measure the resistance with the ECU harness unplugged power off on both the right anf left...Should be about 1 ohm. CX500T 1982 (3) Transalp 1989 GL1100 1983 XL250R 1987 NT650 1988 TRX250 1986 CT90 1972 C70 1981 XR250R 1994    Report

03-04-2010, 3:00 PM George in Indiana Joined on 03-03-2006 Posts 954 Re: cx 500t engine runs 3 seconds then shuts off The bl/br wire must ground out fine for the 3 second run time to work. Plus he said the bike ran when that wire was grounded. As far as the injectors go, I'd be looking at the display on the ECU after the bike dies. If the ECU knows enough to stall the bike, it knows enough to set a fault code for which ever injector failed. I mentioned the yellow/red wire from the start button pages back and even tried it on my bike to confirm. I believe that wire gets 12 volts constant when the ignition key is turned on which causes the bl/br wire to ground for 3 seconds. Then when the start button is pushed, it drops that 12 volts (as when the headlight goes out) and the 12 volts comes back as soon as the button is released causing another 3 second cycle. If that's the way that circuit works, there's a good chance it was put there to "buy time" for another circuit to prove before engaging the bl/br ground wire. And Dan, just so we're on the same page...you did install the other tip over sensor, correct? CX500 TURBO CX650 TURBO '04 GSX1300R Hayabusa    Report

03-04-2010, 3:38 PM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off Thanks Showkey... I agree with you about the bl/br wire not getting its signal through the ECU..... As mentioned I get no fault codes on the ECU which is bugging me. Good idea on the GL 1200 for clues... Will Do if I can get my mitts on a manual.. Dan    Report

03-04-2010, 3:42 PM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off Hello George... yes installed tip over sensor that Pete sent me... no improvement at all... same symptoms .... If I unplug the sensor then it all shuts down and I confirmed that the shut off sensor will work by tricking the tip over sensor in my hand and witnessed the sensor work properly... So the tip over sensor is not it...    Report

03-04-2010, 3:47 PM showkey Joined on 03-02-2007 Northern IL Posts 70 Re: cx 500t engine runs 3 seconds then shuts off We are going in circles......I know its been sorta swapped but it sure would be nice to try a "known good ECU" in gliders bike What is the voltage on your Y/R: cranking? and with the problem? and the voltage on the green wire at the ECU is always zero? right? NEW theory you had two problems and during the testing after you got the ECU back from PK 12 volts was appiled to the BL/BR wire which would be short to ground through the ECU (bad) Remove the ECU pull the covers and look and trace the board and connections at the BL/BR and look for the burnt circuit..... CX500T 1982 (3) Transalp 1989 GL1100 1983 XL250R 1987 NT650 1988 TRX250 1986 CT90 1972 C70 1981 XR250R 1994    Report

03-04-2010, 4:25 PM George in Indiana Joined on 03-03-2006 Posts 954 Re: cx 500t engine runs 3 seconds then shuts off At least I think we're all learning a lot of valuable information on unexplored territory. :) Right about now the last straw I'm grasping at is the black wire that goes from the fuel pump relay positive coil side to the ECU. There must be some reason to send 12 volts to that pin? If that's ok what can be left other than the ECU, and yet that worked fine for Pete. Manual states something along the lines of not confusing the pump and main relays but those are the same. Slim possibility the connectors were pulled out of the molex plugs at one point and accidently swapped by the previous owner? And going way out in left field here...I installed a rather complex paging alarm system in my Hayabusa. One of the features is a kill circuit that activates when the alarm is triggered. I chose to disable the fuel pump coil side from deep within the bikes wire harness. Possibility of an old hidden kill switch doing the same thing on his bike? CX500 TURBO CX650 TURBO '04 GSX1300R Hayabusa    Report

03-04-2010, 4:34 PM George in Indiana Joined on 03-03-2006 Posts 954 Re: cx 500t engine runs 3 seconds then shuts off Good point on the bl/br that he jumpered brown. He also mentioned it fries the relay. Although I was under the impression he did that before sending the ECU to Pete. Maybe not? CX500 TURBO CX650 TURBO '04 GSX1300R Hayabusa    Report

03-05-2010, 7:17 AM Matt_the_Rat Joined on 11-11-2008 Northwest FL Posts 170 Re: cx 500t engine runs 3 seconds then shuts off I'm not a turbo guy, but I was reading through this thread. I've got plenty of car EFI experience. Without knowing the full story on how the system works on these bikes, I still have a simple explantion. The EFI has a start mode and a run mode. When starting the EFI fires the bike. When you let go of the starter, the EFI looks for confirmation that the engine is running. This is found at the air flow sensor, (on jap car EFI systems from the same era.) I don;t know what kind of airflow, or MAP sensor these things use but in my humple, unexperienced opinion, I would think that the ECU is not getting the signal from the intake side, comfirming the engine is running. Maybe I helped, maybe not    Report

03-05-2010, 6:43 PM MotoMartin Joined on 03-02-2010 Oceanside California Posts 36 Re: cx 500t engine runs 3 seconds then shuts off I think Matt is on the right track. It may be an issue with the sensors. i would make sure that the sensor hoses are all good (and they are hooked up to the correct location). Look at page 24-17 of the shop manual if you have it. My money is on the PB sensor being bad or the hose off, hooked up to the wrong location or leaking. There are also jets where the sensor hoses connect that could be blocked.    Report

03-05-2010, 7:54 PM George in Indiana Joined on 03-03-2006 Posts 954 Re: cx 500t engine runs 3 seconds then shuts off ECU is self diagnosing. Faulty sensor means a fault code for that sensor. There are also fail safes programmed for pretty much every sensor allowing the bike to run. No MAF sensor but I do believe what Matt said about a start and run mode. The problem is finding out what input the ECU is looking for. I'm stilling guessing the black wire from the fuel pump relay to the ECU. Ignition switch, kill switch and tip over sensor would kill 12 volts to that circuit. We know it gets 12 volts to the pump relay, we don't know if it gets 12 volts from that point to the ECU. Bad wire, bad pin? CX500 TURBO CX650 TURBO '04 GSX1300R Hayabusa    Report

03-05-2010, 8:13 PM MotoMartin Joined on 03-02-2010 Oceanside California Posts 36 Re: cx 500t engine runs 3 seconds then shuts off I would't rely on the self diagnostic function of the ECU. The fuel injectors on my turbo were not working but there was no ECU code showing. The P1, P2, T1 and throttle sensors do not effect starting but the PB and TW sensors can. Have you removed the jet of the PB sensor and cleaned it?    Report

03-05-2010, 11:42 PM George in Indiana Joined on 03-03-2006 Posts 954 Re: cx 500t engine runs 3 seconds then shuts off If the Pb sensor fails, the bike will still run with readings off the engine speed sensors and TPS. If someone was having a really bad day where the Pb AND TPS sensor failed at the same time, the ECU would then substitute a fixed value and the bike would still continue to run. On the other hand, if the Pb sensor is causing some kind of flaky problem (maybe like a stuck flat reading for a non running bike) and the ECU does look for the signal from that sensor for confirmation that the bike is running, he could just simply unplug the sensor causing a failure that the ECU will notice and the bike should start up in fail safe mode. The 3 second run time at start would allow enough run time for that sensor to take over. CX500 TURBO CX650 TURBO '04 GSX1300R Hayabusa    Report

03-06-2010, 12:31 AM George in Indiana Joined on 03-03-2006 Posts 954 Re: cx 500t engine runs 3 seconds then shuts off Ok, this is out of the other manual: So we know for sure the ECU is looking for a signal that the engine has started.  Another direction...could it be looking for feedback from the spark unit?  The Pign sensor is not monitored by the ECU but that looks like it mainly controls the boost meter...yet the manual does list it as a possibility for many poor running symptoms. CX500 TURBO CX650 TURBO '04 GSX1300R Hayabusa    Report

03-06-2010, 6:10 AM showkey Joined on 03-02-2007 Northern IL Posts 70 Re: cx 500t engine runs 3 seconds then shuts off The ECU is only looking at the fuel injectors for open and or shorts.....if the injectors are dirty, stuck shut with bad gas etc there most likely be no ECU code....... CX500T 1982 (3) Transalp 1989 GL1100 1983 XL250R 1987 NT650 1988 TRX250 1986 CT90 1972 C70 1981 XR250R 1994    Report

03-06-2010, 6:34 AM CXTURBOBOOST Joined on 05-02-2007 Lincoln, NE Posts 440 Re: cx 500t engine runs 3 seconds then shuts off Guys, I don't know how many times I can say this.......The bike runs fine when 12v is applied to FP. He can ride the bike and all is normal. I believe a wire is bad in the harness or at a connection... Yes, the ECU looks to see if the bike is running. If the wires going to or from are bad, it won't work. George is right on the default mode. Bike will still run and flip a code. Injectors are fine, they have been professionally cleaned, flow checked and re-installed. PK    Report

03-06-2010, 10:20 AM showkey Joined on 03-02-2007 Northern IL Posts 70 Re: cx 500t engine runs 3 seconds then shuts off I agree my last comment on the injectors was a reply to the posting that ECU codes are not reliable. There is an input problem to the ECU wires sensor etc not as likely since it runs good, BL/BR fault from ECU to FP relay or the ECU has fried FP on circuit (after it was set away to the known good bike). Lets run jumper from the BL/BR terminal at the ECU to the FP relay.......... CX500T 1982 (3) Transalp 1989 GL1100 1983 XL250R 1987 NT650 1988 TRX250 1986 CT90 1972 C70 1981 XR250R 1994    Report

03-06-2010, 11:23 AM George in Indiana Joined on 03-03-2006 Posts 954 Re: cx 500t engine runs 3 seconds then shuts off But the bl/br does ground for 3 seconds so that wire path should be ok. It just needs to do it again once the ECU knows the bike is running. I can't believe that FI manual doesn't even mention where the run confirmation input comes from. Honda should have come out with a better suppliment later on. I still think what MotoMartin mentioned about the Pb sensor is a possibility. The ECU may be getting information fed from the TPS and engine speed sensors but a plugged port going to the Pb sensor makes that circuit think the bike never started (and technically it didn't). Put external power to the fuel pump and the other two sensors allow the bike to run. Since the Pb sensor isn't shorted or open, no fault code appears. The ECU programming may not be smart enough to know the Pb sensor output doesn't jibe with the other two sensors. The bike is fooled into running but is it running 100%? We haven't heard back from Dan lately, I hope he didn't give up on it. CX500 TURBO CX650 TURBO '04 GSX1300R Hayabusa    Report

03-06-2010, 12:05 PM showkey Joined on 03-02-2007 Northern IL Posts 70 Re: cx 500t engine runs 3 seconds then shuts off "I can't believe that FI manual doesn't even mention where the run confirmation input comes from. Honda should have come out with a better suppliment later on." Agreed we are short on info: I was hoping someone with 1200I manual would chime in with more info on run confirmation....... CX500T 1982 (3) Transalp 1989 GL1100 1983 XL250R 1987 NT650 1988 TRX250 1986 CT90 1972 C70 1981 XR250R 1994    Report

03-06-2010, 1:02 PM showkey Joined on 03-02-2007 Northern IL Posts 70 Re: cx 500t engine runs 3 seconds then shuts off I have a 1985 and1986 Accord manuals with the first HONDA Automotive FI system. The system is very similar to the 500 Turbo system, uses a two relay system to control the FP. It says the ECU controls fuel pump ground and stops the fuel pump if engine RPM falls below a prescribe limit it also talks about the a two second pump runs with key on and with starter run. Then it goes on with needing a RPM signal to run the pump....... BUT thats all it says troubleshooting is very much the same as the 500T book with alittle more detail. The 1985 book has block diagram showing the crank sensor (engine speed) and the start signal as the only control inputs to the fuel pump control side in the ECU. ???????? CX500T 1982 (3) Transalp 1989 GL1100 1983 XL250R 1987 NT650 1988 TRX250 1986 CT90 1972 C70 1981 XR250R 1994    Report

03-06-2010, 2:08 PM HomerRod Joined on 07-21-2006 Posts 223 Re: cx 500t engine runs 3 seconds then shuts off I'm thinking that the fuel pump relay has an interal open or shrort to ground. If you can somehow bypass it (jumper wire, paper clip, etc) and see if the problem goes away. I alway agree that cleaning and checking grounds will help. Make sure that all connections on the harness are clean and tight. I found my headlamp operating intermittently last week. Pulled the harness connector and found greenish corrosion on one of the spade terminals. Clean and sprayed with WD40, and it is now OK. Also, make sure the ECU harness connector does not have any bent or distored pins that may be misaligned when plugging into the ECU. Get a flashlight and magnifying glass and look at the pins carefully. Electricity is present in the circuit, you just need to make sure it goes to right place. Wiring 12V directly to the pump tells me that something is grounded, partially open or drawing excessive current from high resistance (corrosion, loose fitting, etc).    Report

03-06-2010, 2:42 PM George in Indiana Joined on 03-03-2006 Posts 954 Re: cx 500t engine runs 3 seconds then shuts off RPM would make sense too. He did mention replacing the engine speed sensors at one point in this discussion but then we come back to the bike running fine with the relay jumped out. I wonder if one could be installed right and the other wrong? Last night I was trying to find a path that the spark unit would use to communicate with the ECU but I don't see a direct one. CX500 TURBO CX650 TURBO '04 GSX1300R Hayabusa    Report

03-06-2010, 3:04 PM showkey Joined on 03-02-2007 Northern IL Posts 70 Re: cx 500t engine runs 3 seconds then shuts off "RPM would make sense too. He did mention replacing the engine speed sensors at one point in this discussion but then we come back to the bike running fine with the relay jumped out. I wonder if one could be installed right and the other wrong? " Like you said the pump runs for 3 seconds so the BL/BR is ground working. I think we are back to the engine speed sensor. Did he use the Toyota sensors? Are we back to that speed sensor polarity? The 1200I speed sensor are suppose to also be a direct drop in replacement for the turbo. I also looked at early FI Civics and Prelude and they also use RPM as the input for FP control. CX500T 1982 (3) Transalp 1989 GL1100 1983 XL250R 1987 NT650 1988 TRX250 1986 CT90 1972 C70 1981 XR250R 1994    Report

03-06-2010, 3:18 PM CXTURBOBOOST Joined on 05-02-2007 Lincoln, NE Posts 440 Re: cx 500t engine runs 3 seconds then shuts off If you reverse the polarity on the pick-up coils it will flip a code on the ECU but still run in limp mode.... PK    Report

03-06-2010, 10:46 PM Matt_the_Rat Joined on 11-11-2008 Northwest FL Posts 170 Re: cx 500t engine runs 3 seconds then shuts off I read in on what you guys found from the Honda EFI. there is also used a spark confirmation signal. This would be an ignition signal coming from the pick up coil, (again I don't know what these use for a distributor. If you have some info on the names of the pins of the ECU, or the wires coming to it, I don't know old honda efi that well but toyota used a label like IGt or IGf on the ECU pin to show the spark confirmation. I still hold fast to my origional opiniion, the ECU does not know the engine is running, so the pump relay does not remain on. If someone could maybe post a pic of the EFI wiring diagram, that would be helpful    Report

03-07-2010, 7:50 AM showkey Joined on 03-02-2007 Northern IL Posts 70 Re: cx 500t engine runs 3 seconds then shuts off Hey, Matt.....no connection on the 500T from the spark unit to the FI system. This is a very "simple" FI system and the inputs consist of: 2 rpm sensors (crank position) 3 air pressure sensors 1 throttle position 1 air temp 1 water temp None of which get back to the spark unit. The spark unit has it own air pressure sensor and pick-up coils. CX500T 1982 (3) Transalp 1989 GL1100 1983 XL250R 1987 NT650 1988 TRX250 1986 CT90 1972 C70 1981 XR250R 1994    Report

03-08-2010, 7:09 PM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off Hello Matt and welcome to group and your input is certainly appreciated... I think you are absolutely on the mark.  The computer is not getting a signal to run the engine once it has been initialized by the start button... So the next time I get back to the motorcycle I will get on to the vacuum hoses and recheck the engine speed sensors which I installed earlier in this process.  According to Pete I could have the polarity reversed on the engine speed sensors which I removed and replaced earlier in this process.  BTY thanks everyone I am learning a LOT through all of this thread. Dan (gliderbuff)    Report

03-08-2010, 7:19 PM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off I am headed toward the engine speed sensors next session on the machine... good thing to check... I think is was a Toyota sensor... came from NAPA auto parts and was the exact same sensor that was in the motorcycle originally .   The anti freeze had gotten the original speed sensors... But I think problem lies in the "run signal" not getting to the ECU once I let go of the start button.  Dan    Report

03-08-2010, 7:32 PM George in Indiana Joined on 03-03-2006 Posts 954 Re: cx 500t engine runs 3 seconds then shuts off I'd try the easy stuff first.  Unplug the Pb sensor so the ECU sees an outright failure and then try to start the bike.  If the bike runs with an error code you've found the problem area with about 10 seconds of work. CX500 TURBO CX650 TURBO '04 GSX1300R Hayabusa    Report

03-08-2010, 7:36 PM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off Hello Showkey... took ECU covers off and peered in and all nice green circuit boards pretty silver solder .... no brown or burned places what so ever .... so I doubt I am at the problem just yet.  Dan    Report

03-09-2010, 1:29 AM Don in Oz Joined on 03-10-2006 Melbourne, Australia Posts 546 Re: cx 500t engine runs 3 seconds then shuts off Gliderbuff, I'm back from our Oz CX/GL rally - 43 CX/GL bikes all in one RV park - pictures should be on our Oz website by now. Have you checked to see whether the 5 volt supply remains available at any/all of the pressure sensors (except the P ign sensor) after you have heard the fuel pump run for its first three seconds? If that fails, then you have a good ECU which is being overloaded by one of the external sensors that it supplies with power. Don. GL500I, CX500TC (2), CX500EC (2), 1982 CX500C. GL1000, 1976 CB550F, CT110 (2), XL125S (2), 1973 CB175K6. Kwaka Z250C1 (2). Suzuki GS450SX, DR250SJ, GS125ESD.    Report

03-09-2010, 1:38 AM Don in Oz Joined on 03-10-2006 Melbourne, Australia Posts 546 Re: cx 500t engine runs 3 seconds then shuts off Gliderbuff, You can disregard the Pb and P2 sensors as having a fault and causing your symptom. Turbos that I have done fault-finding on have both run quite "normally" in the limp-home mode with those sensors faulty. One turbo actually had the Pb and P2 sensor air tubes reversed, and it still ran - in a kind-of-a way. Don. GL500I, CX500TC (2), CX500EC (2), 1982 CX500C. GL1000, 1976 CB550F, CT110 (2), XL125S (2), 1973 CB175K6. Kwaka Z250C1 (2). Suzuki GS450SX, DR250SJ, GS125ESD.    Report

03-09-2010, 6:28 AM George in Indiana Joined on 03-03-2006 Posts 954 Re: cx 500t engine runs 3 seconds then shuts off If the ECU is being overloaded by one sensor would the bike run with an external 12 volt supply to the fuel pump?  If it did run, wouldn't there be one or more fault codes showing up, especially for the overloaded sensor? We know for a fact the ECU looks for a running engine signal as stated in the FI manual. Where does that signal come from? The Y/R wire most likely breaks and makes again at the push of the starter button to engage the 3 second run time.  Most likely it's buying 3 seconds of run time so that it doesn't confuse starter cranking with normal engine running along with waiting for a reliable sensor reading. Now if the Pb sensor is giving a signal for a NON running engine which is of course within its normal perimeters, why would the ECU set a fault code?  Yes, it sees a running feedback from the speed sensors but is the 1981 ECU smart enough to understand two conflicting sensor reports?  And if it does, which would it believe and report as the faulty sensor circuit? Reversed hoses or breaking/shorting the Pb sensor will give a reading outside normal perimeters, set a fault code and allow the ECU to bypass that sensor. He has a bizarre problem and at this point I wouldn't disregard anything that's remotely possible.  It would take a couple of seconds to unplug the Pb sensor and see what happens.  Rule that out and then start digging into speed sensors. And yes the speed sensors would seem to be a logical choice for supplying the "running engine signal" but how could the engine run at all if that circuit was completely screwed up?  One good sensor and it'll run with a fault code.  Two bad sensors and the bike can't physically run at all.  His bike runs the 3 seconds or continuously with the fuel pump hot wired and he says no fault codes. CX500 TURBO CX650 TURBO '04 GSX1300R Hayabusa    Report

03-09-2010, 11:33 AM Don in Oz Joined on 03-10-2006 Melbourne, Australia Posts 546 Re: cx 500t engine runs 3 seconds then shuts off OK, George. We know a 500T gives a fault code with one of the Ne sensor coils faulty but the bike will continue to run, but if both Ne coils are faulty - or both connected round the wrong way - I wonder if the bike's ECU thinks the motor is not running. If they are both connected around the wrong way, the ECU may think the motor is running backwards. A very easy check on the "both faulty" would be for someone to unplug their Ne sensor cable entirely, and see if the motor WILL run. Testing for both Ne coils reversed will take a bit more work - removing the pins from the connector block and reversing the coil's polarity by interchanging their pin positions in the block, and re-connecting. Don. GL500I, CX500TC (2), CX500EC (2), 1982 CX500C. GL1000, 1976 CB550F, CT110 (2), XL125S (2), 1973 CB175K6. Kwaka Z250C1 (2). Suzuki GS450SX, DR250SJ, GS125ESD.    Report

03-09-2010, 11:47 AM Don in Oz Joined on 03-10-2006 Melbourne, Australia Posts 546 Re: cx 500t engine runs 3 seconds then shuts off George, I'm beginning to wonder whether the fuel pump is meant to start again instantaneously when you press the start button, or whether it waits for the Ne sensors to tell the ECU that the motor has turned over. I would guess that the Ne sensors are THE definitive indication to the ECU that the motor is turning, and that they over-ride any other sensor. Once again, just unplugging the Ne sensors on a good bike will solve this quandary. Don. GL500I, CX500TC (2), CX500EC (2), 1982 CX500C. GL1000, 1976 CB550F, CT110 (2), XL125S (2), 1973 CB175K6. Kwaka Z250C1 (2). Suzuki GS450SX, DR250SJ, GS125ESD.    Report

Page 3 of 4 (177 items) < 1 2 3 4 >

Honda CX500 & G... » CX500 GL500 Tra... » CX500 & CX650 T... » cx 500t engine runs 3 seconds then shuts off

(please select) Forums Home |- Search Forums |- Active Topics |- Unanswered Posts User Options |- Sign In |- Join this community |- Forgot Password CX500 GL500 Transverse Twins Discussion Forum |- General Discussion |- CX Customization and Modifications |- CX500 & CX650 Turbo Forum |- Travelling, Friends, and Trips |- Selling and Buying Forum |- Technical Help Forum Other Forums |- Off-Topic Posts |- Test Forum