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03-09-2010, 5:10 PM George in Indiana Joined on 03-03-2006 Posts 954 Re: cx 500t engine runs 3 seconds then shuts off A while back I was thinking maybe one backwards one correct.  Now if it thinks the engine is running in reverse, could it even process that signal and allow the bike to run?  Something in that circuit can be confusing the ECU and not dropping a fault code.    If I blip the start button on mine it does cycle the fuel pump each time.  If you follow the y/r wire from the ignition, it goes to the starter relay and to the ECU. Looks like when the the start button is pushed, the headlight circuit opens and power is sent from bat2 to the y/r wire (sends 12 volts to the starter relay and ECU).  When released it goes back to bat3 to headlight. We probably get our fuel pump run time from when the ECU sees that 12 volts on the y/r wire...but what causes the 3 second run when the ignition key is first turned on?  Could it be on the bl wire form the fuel pump relay to the ECU? At this point I think the only places a run signal can come from would be the speed sensors or Pb sensor.  Other sensors such as temperature wouldn't show the instant change that's needed to confirm engine running. I wonder if Nippondenso has a theory of operation manuals for their ECUs. CX500 TURBO CX650 TURBO '04 GSX1300R Hayabusa    Report

03-09-2010, 5:54 PM Don in Oz Joined on 03-10-2006 Melbourne, Australia Posts 546 Re: cx 500t engine runs 3 seconds then shuts off A mate of mine with a CX500T - who I mentioned this problem to at our CX/GL rally over the weekend - has just simulated Gliderbuff's fault. Graham pulled the Ne sensor plug and tried to start his bike - it did for about 3 seconds, then wouldn't continue. LOOKS LIKE A SOLUTION IS AT HAND. 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, 6:25 PM George in Indiana Joined on 03-03-2006 Posts 954 Re: cx 500t engine runs 3 seconds then shuts off Excellent!  Did he say if it showed an error code? Almost 30 years and these bikes still hold secrets. :) CX500 TURBO CX650 TURBO '04 GSX1300R Hayabusa    Report

03-09-2010, 7:25 PM CXTURBOBOOST Joined on 05-02-2007 Lincoln, NE Posts 440 Re: cx 500t engine runs 3 seconds then shuts off Could be... He did replace the coils on the speed sensors.. He may have soldered both wires so that neither coil is in the right direction? PK    Report

03-09-2010, 9:06 PM MotoMartin Joined on 03-02-2010 Oceanside California Posts 36 Re: cx 500t engine runs 3 seconds then shuts off The Ne or engine speed sensor makes sense when you look at the CFI system diagram and previous posts.Theoretically then, the ECU is not getting a signal that the motor is running from the engine speed sensor and turns off the power to the fuel pump. Either the wire is off or the sensor broken. The only issue i have with that is the shop manual states "if one sensor fails, injector contiues on timing for the remaining sensor." Not sure that I understand how that works... The speed sensor is definately shown as a possible cause of problms in the troubleshooting reference chart.    Report

03-09-2010, 10:02 PM Don in Oz Joined on 03-10-2006 Melbourne, Australia Posts 546 Re: cx 500t engine runs 3 seconds then shuts off George, It didn't throw an error code when the Ne sensor plug was removed. Graham also gave some details about what happened when he swapped various wires, and when his bike would run and not run. If someone wants to get a copy of Graham's emails, then I could forward them to your email address for onforwarding. (Can we direct-message people on this BB without the text - and address - being show on this page?}. 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

03-10-2010, 4:30 AM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off Hello Pete... I think you and the group are on to it now.... there is a good possibility that I could have very well done that... will check today and see if i got the polarity wrong.... since they obviously are  installed way inside the engine behind the water pump with a blue white and yellow wire leading out of the sensors.  white i guess is the negative side (ground) and blue is left and yellow is right?  Thats what the schematic depicts .   I was under the impression that a coil wasn't necessarily directional but rather if the proper resistance was there then all was well.   Correct me if I am wrong.  More clues to the puzzle .... the spark plugs are really really carbon'd up.  Reminds me of a carburated  engine that has been left running with the choke on... something is very wrong there and that could be the sensors too perhaps?    Dan    Report

03-10-2010, 4:41 AM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off Thanks MotoMartin... I will be getting into the sensors today and let you know what I find out.... like Pete says I could have the polarity screwed up and causing all my problems!  I think I am getting schooled on inductance coils..... eeks pretty basic... lets assume I have the coils installed wrong.. How should I go about figuring out which one is which??  Dan    Report

03-10-2010, 5:06 AM CXTURBOBOOST Joined on 05-02-2007 Lincoln, NE Posts 440 Re: cx 500t engine runs 3 seconds then shuts off It does make a difference. It will trip the speed sensor code if you have two wires reversed and go in limp mode. Once you reverse to correct order all is well.... I don't know what it does if both coils (4 wires) are reversed. Could be your problem. Check it out. Pete    Report

03-12-2010, 6:02 AM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off Hello Pete... If I check the resistance in the pulse generators I get the readings the shop manual calls for 85 ohms..... white is the common wire.  so that seems right ... is there a further check to see if the polarity is right you might know about.  I am trying to jog my memory about those sensors but I believe there was  red and white wire or red coming off the pulse generator... If I remember correctly I soldered the two whites together connected them up to the white wire leading into the wiring harness the red wires one to the blue wire and the other to they yellow wire.  I suppose I could have the left and right mixed up and engine still runs ... but sends the wrong  signal to the ECU ... I am going to try to see if reversing the yellow and blue does anything... what do you think... Dan    Report

03-12-2010, 6:19 AM CXTURBOBOOST Joined on 05-02-2007 Lincoln, NE Posts 440 Re: cx 500t engine runs 3 seconds then shuts off You should have had two wires on the coils, and two wires on the harness per coil (4 total)...Regardless of the way you connected the wires...you can always change the position of the pins in the connector. You can try it all different ways as far as the alignment arrangement. Just pull the plug apart, used a dental pick or small object to release the pin out of the harness connector, and swap around. Pete    Report

03-12-2010, 7:02 AM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off Forget this post... Pete set me straight .... I was checking wrong pickups... .... Dan    Report

03-12-2010, 8:29 AM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off Ok .... its time to pass the torch... I am listing the bike for sale on craigslist here and ebay.  I would like to get $1800 for it as is in Atlanta.  The good... low mileage engine 6060 all the electrics work save the electrical gremlin this thread talks about.and body work seat and upholstry is quite good and intact.    I would call the bike a 6 or 7 out of 10.  The bad is that it may be a parts bike for someone because I was unable to get the title from the person I bought the bike from locally.  Of course I do have a Bill of Sale.   Short of getting it running I have been unable to make it sustain running  without tricking the fuel pump with a jumped 12v power source.  So if you are interested and would like pictures my email is gliderbuff@yahoo.com.  Thanks all... Dan    Report

03-12-2010, 12:13 PM HeadScratcher Joined on 03-13-2010 Posts 8 Re: cx 500t engine runs 3 seconds then shuts off Aha! I am the new torch bearer, having bought Dan's bike this afternoon. I won't be able to look at it until Monday, but having glanced through this post I think the first thing is to write down all the sensors which couldbe the source of the " I am running" siganl the ECU is looking for, then methodically unpluggin each one, and faking the sensor output to see if it starts. I also wondered if there is a fuel pressure sensor somewhere whcih tells the ECU that it needs gas, so please switch onthe pump, rather than just "the engine is running please supply fuel constantly" On a running bike, does the pump initialise for 3 seconds, then run permanently when the engine is running, or only when the fuel system needs to be pressurised? Can't wait to get my hands dirty on it....    Report

03-12-2010, 12:52 PM Timothy_D Joined on 04-22-2006 Santa Rosa, CA Posts 1,585 Re: cx 500t engine runs 3 seconds then shuts off There is a fuel pressure regulator, but I believe it is vacuum operated, not electrical. CX500 Turbo, GL650I, Two CX650E's, and one Crown Jewel of the CX line- CX650T. Why do I own five CX/GL bikes? Ask an alcoholic why he drinks. Donating Member. Sold: 1981 CX500D, 2- 1982 CX500T's, 1983 CX650C.    Report

03-12-2010, 1:30 PM HeadScratcher Joined on 03-13-2010 Posts 8 Re: cx 500t engine runs 3 seconds then shuts off If I don't figure it out first day, I'm going to wire up the pump to the oil pressure switch, so it only runs when there is oil pressure like most fuel pump shutoffs. Of course, that's ok if the pump is supposed to be on permanently when the engine is running. Can someone please confirm if it is? If not, then it's almost certain to be a sensor in the fuel supply somewhere and having it run full time could be bad. I think I still need to check the wiring done by Dan of 2 sensors in the water pump, as from the above it seems they may be reversed polarity. True? Thanks.    Report

03-12-2010, 3:15 PM showkey Joined on 03-02-2007 Northern IL Posts 70 Re: cx 500t engine runs 3 seconds then shuts off Pump should be on any time the engine is running. Vacuum regulator with a fuel return line back to the tank. A relay with the oil pressure to ground the coil would be a good work around. Pending confirmation of gliders past testing and repairs. I would guess something we already talked about many times was over looked or got lost in the "translation". If glider did not have or provide the factory manual that is critical in your up coming quest. CX500T 1982 (3) Transalp 1989 GL1100 1983 XL250R 1987 NT650 1988 TRX250 1986 CT90 1972 C70 1981 XR250R 1994    Report

03-12-2010, 6:36 PM Don in Oz Joined on 03-10-2006 Melbourne, Australia Posts 546 Re: cx 500t engine runs 3 seconds then shuts off The fuel pressure regulator is air operated by adding or subtracting the inlet manifold pressure on the control side of the regulator's diaphragm. You won't be able to use the oil pressure switch, as the oil pressure probably won't be there soon enough - also the switch "earths" the "cold" side of the oil pressure lamp, which doesn't pass very much current to fully light it - you may have to put a higher current light in that socket in the dash. 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

03-12-2010, 7:58 PM MotoMartin Joined on 03-02-2010 Oceanside California Posts 36 Re: cx 500t engine runs 3 seconds then shuts off Headscratcher, congratulations on your purchase and good luck with your project. Please keep us informed with how you get on, hopefully it is something simple. Maybe we should start a pool, I think the engine speed sensor looked like the odds on favorite a few days ago.    Report

03-13-2010, 10:50 AM HeadScratcher Joined on 03-13-2010 Posts 8 Re: cx 500t engine runs 3 seconds then shuts off OK, I've had a better look at this thread, and a quick go on the bike. As of now, it will start and trun until the gas from those first 3 seconds of fuel pump operation runs out. If I short the black/brown to earth, it will run on and on and on...but I stop quickly, in case the reason it isnt working is because there IS a problem ans shutting down the engine prevents damage! I am sure the issue is the ECU not receiving the "engine is running" code. From this thread that seems to be because either the Pb sensor is dud, or the Ne sensors are mis-wired. SO, 2 questions- 1 what and where is the Pb sensor, and what are the correct readings for correct functioning? Apologies if this is in the manual that Dan passed on-I will search for it there too. 2 how do I tell if the Ne sensors (are they labelled NL and NR on the wiring diagram?) are miswired without removing them (preferably) or with removing them? If they are just coils, then I'm unsure how they could be miswired anyway(unless more than a polarity switch) I intend to have a proper go on Monday-at which time I shall investigate these options, and then short the FP relay signal to earth and let the bike warm up a bit, in case it dislodges something and helps, but I'd rather know that the Ne sensors are correct before proceding! Appreciate all your help to Dan so far, it cuts down a lot of work now, and it will be super when it gets going!    Report

03-13-2010, 2:38 PM HeadScratcher Joined on 03-13-2010 Posts 8 Re: cx 500t engine runs 3 seconds then shuts off Now running!! I let it run for a minute with no problems. Ne sensors/engine speed sensors/"water pump" sensors were problem. More detail to follow as am playing with my son outside. He helped, I think. Yippee!    Report

03-13-2010, 7:30 PM HeadScratcher Joined on 03-13-2010 Posts 8 Re: cx 500t engine runs 3 seconds then shuts off OK, well after reading theses posts thoroughly and having a think, I decided that the most likely cause was the speed sensors. Firstly, because I had reached the conclusion that the ECU was missing the "engine is running" signal referenced above (and I thought the wording may have been precise, as it would have been written by Japanese engineers, so I was looking for a signal that said RUNNING rather than PRODUCING PRESSURE) and also because Dan had already found that the sensors were dead, and had replaced them, and that hadn't made any difference. I might not have looked there if he hadn't noted that he may have got the outputs mixed up. As a warning to anyone else replacing them, take digital pictures of the position of the sensors and their wires colours before removing them and then check it afterwards. (Edit-If you are taking sensors from a Toyota, the polarity may be different anyway, but at least you'd know which wires were pairs, so you'd only have 4 permutations to try) So here's what I did. I found the speed sensor connectors, and unplugged them so I could test the 4 leads going in to the water pump housing. 2 were giving a reading of 185 ohms, so were another two. So, I knew which two made up each sensor. From the wiring diagram, I knew that the brown wires on the engine side of the harness were connected together, so I had to match a brown wire and another coloured wire to each sensor pair. I thought perhaps each pair had been wired to the other's connection, so that instead of (say) a 70 degree angle between each sensor, there was a 290 degree angle being seen by the ECU. So I swapped them round. No difference. Then I just ran through the possible permutations, bearing in mind I knew each pair of sensor wires, but had no idea of polarity. I thought that polarity couldn't affect the output of a coil, therefore I had no problems in swapping them over to see if it helped, rather than assuming it couldn't make a difference and refusing to try it! So far, I've run it for a minute, and all was well. Perhaps a little rough-possibly quite rich inside the cylinders having been only run for 3 second periods(ie on the EFI equivalent of "full choke") in the last 20 years-but once I've cleaned up the area and got the pump safely stowed and the wires replaced in position, I'll fire it up and leave it running for a bit to clear out the old gunk, while keeping an eye on the temperature. Then I need to bleed the brakes-I've read it has 82bhp, so I want to be able to stop it while I test drive it! I'll get a picture of it up if I can in the next couple of days-hoping for bright weather on Monday so I can give it a solid clean. I'll be back to provide follow ups in due course!    Report

03-13-2010, 7:41 PM HeadScratcher Joined on 03-13-2010 Posts 8 Re: cx 500t engine runs 3 seconds then shuts off PS to the idea of using the oil pressure switch-I was going to use a Normally Closed relay fed through a diode to the oil pressure switch, using a switched positive on the other side of the energising coil, to make a connection to earth for the black/brown wire (the ECU FP output) and thus energise the FP relay without reverse voltages messing up the oil pressure light. As the engine was staying running as long as the ignition button was being pressed, I was hopeful that the oil pressure would build up enough to allow my little scheme to work-my oil pressure light went off immediately after I released the button while testing the bike earlier, so it probalby would have done-it is a cowboy version of the oil pressure relay box used in the Audi quattros, which failed after a while, and were $250 each to replace! A poster above mentioned his VW had a similar set up, and that reminded me of the solution I reached many years ago when working on my quattro, and which I couldn't quite recall when I was buying the bike from Dan. Its good to know that a solution has been found, and a little bit more learned about these bikes (and hey, I've got a WHOLE LOT to learn!!)    Report

03-13-2010, 7:54 PM George in Indiana Joined on 03-03-2006 Posts 954 Re: cx 500t engine runs 3 seconds then shuts off Good job!  Sounds like that CXT has found a good home with you. Plus we all have some valuable information to add to our notes.  This might be one of the best CXT threads ever! CX500 TURBO CX650 TURBO '04 GSX1300R Hayabusa    Report

03-20-2010, 1:42 PM HeadScratcher Joined on 03-13-2010 Posts 8 Re: cx 500t engine runs 3 seconds then shuts off Now here's a thing.... I was tidying up the wiring a bit, and had a thought. I unplugged one wire from one pair of sensor wires, and the bike stopped. I plugged it back in, then unplugged one wire form the OTHER pair of sensor wires-the bike kept working. This told me that I'd got one pair of sensor wires in the wrong wasy round, and that when I unpluggd one wire form the "good" sensor, the bike couldn't run. So then I was able to reverse one pair, and then if I unplugged one wire from either sensor the bike would keep running. So if you do put in new sensors, or think that poerhaps one sensor has died (perhaps due to a little loss of performance), its worth a little check to make sure you have them all wired up properly.    Report

03-26-2010, 7:37 PM gopher Joined on 11-06-2008 Sk.Ca. Age 56 Posts 608 Re: cx 500t engine runs 3 seconds then shuts off This has been an excellent thread.  Focused, friendly, and informative.  The bad thing is I have realized I'm too stupid to own a turbo. 1981 GL500I    Report

04-01-2010, 4:12 AM gliderbuff Joined on 02-20-2010 Posts 51 Re: cx 500t engine runs 3 seconds then shuts off I could not agree with gopher more and thanks for all your help... I hope headscratcher is able to put a ton of miles on the resurrected machine.  In the meantime gliderbuff keeps watch over this post as an keeps on learning... I watch my new company grow........www.dansmotorcycles.com....... check it out.... Dan Person    Report

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