'83 No-Start - Please Help
02-09-2003, 05:11 PM
#1
Instructor
Thread Starter
'83 No-Start - Please Help
I am a having major problem with my '83 928s.
The car starts immediately but as soon as the cold start valve turns off, it stalls (fuel pump is running - can hear it for couple of seconds after it stalls).
Have checked the following: Good spark, compression in all cylinders, all sensors, (including AFC) of fuel injection system, all resistance, voltage and ground terminals at ECU, voltage to both sides of fuel injectors (both rails) while running, fuel pump pressure, flow, and ability to hold pressure after shutoff, and have checked for vacuum leaks about 10 times.
Any ideas where the problem could be?
Joseph
The car starts immediately but as soon as the cold start valve turns off, it stalls (fuel pump is running - can hear it for couple of seconds after it stalls).
Have checked the following: Good spark, compression in all cylinders, all sensors, (including AFC) of fuel injection system, all resistance, voltage and ground terminals at ECU, voltage to both sides of fuel injectors (both rails) while running, fuel pump pressure, flow, and ability to hold pressure after shutoff, and have checked for vacuum leaks about 10 times.
Any ideas where the problem could be?
Joseph
02-09-2003, 05:19 PM
#2
I had this problem.
I cleaned all grounds, but at the same time "correctly" jumpered my AFC relay, with a THREE PRONG jumper, and the car starts and runs.
There are TWO 92) 87 terminals on the AFC relay that must be connected to the term 30... Why? I have no idea.
I cleaned all grounds, but at the same time "correctly" jumpered my AFC relay, with a THREE PRONG jumper, and the car starts and runs.
There are TWO 92) 87 terminals on the AFC relay that must be connected to the term 30... Why? I have no idea.
02-09-2003, 11:49 PM
#3
Instructor
Thread Starter
Brendan,
Thanks for the reply.
I did check for voltage at the AFC with the key on and it checked out ok. But I will definitely give it a try first thing in the morning.
Joseph
Thanks for the reply.
I did check for voltage at the AFC with the key on and it checked out ok. But I will definitely give it a try first thing in the morning.
Joseph
02-10-2003, 02:07 AM
#4
Burning Brakes
Hi Joseph,
My car had the same problem after I left it sitting a long time... the car would start great and run for about 1.5 seconds. After several starts, it would still crank but wouldn't light off again until several hours had passed (enough time for the temp sensor which controls whether or not to fire the cold start valve to cool down). The problem was a bad $15 fuel injection relay.
Since you're getting voltage to the fuel rails (and I wasn't), it sounds to me like a ground issue. This topic has come up before in the last couple of months. The injection system on our cars works by sending 12V full-time to the injectors, and it's only the *ground* that gets switched by the control box which gets them to fire.
If you have a wiring diagram, and/or can trace the ground(s) out from the control box, I'd check there for sure. Might also be worth investing the $15 for a new relay just in case.
Good luck,
Rick
My car had the same problem after I left it sitting a long time... the car would start great and run for about 1.5 seconds. After several starts, it would still crank but wouldn't light off again until several hours had passed (enough time for the temp sensor which controls whether or not to fire the cold start valve to cool down). The problem was a bad $15 fuel injection relay.
Since you're getting voltage to the fuel rails (and I wasn't), it sounds to me like a ground issue. This topic has come up before in the last couple of months. The injection system on our cars works by sending 12V full-time to the injectors, and it's only the *ground* that gets switched by the control box which gets them to fire.
If you have a wiring diagram, and/or can trace the ground(s) out from the control box, I'd check there for sure. Might also be worth investing the $15 for a new relay just in case.
Good luck,
Rick
02-10-2003, 09:57 AM
#5
Rennlist Member
Rennlist Site Sponsor
Get a mechanic's stethoscope and listen to the injectors as someone cranks the engine. There should be a steady "click-click-click..." as the engine spins.
If there is no clicking, the injection Control Unit is not grounding the injectors.
Check for 12 vdc with the ignition switch on at ther red wire (10) and the red/blue wire (29) at the Control unit.
Using an analog voltmeter, check with the starter operating for pulsing voltage on the black/gray wire (1) at the control unit. If there is no pulse, the link to the ignition unit green wire is bad.
If there is no clicking, the injection Control Unit is not grounding the injectors.
Check for 12 vdc with the ignition switch on at ther red wire (10) and the red/blue wire (29) at the Control unit.
Using an analog voltmeter, check with the starter operating for pulsing voltage on the black/gray wire (1) at the control unit. If there is no pulse, the link to the ignition unit green wire is bad.
02-10-2003, 10:06 PM
#6
Instructor
Thread Starter
Thanks Brendan, Rick, and Wally.
Found good pulsing voltage at (1) at ECU. Am working alone so couldn't listen for clicks at injectors while cranking, so hooked up small bulb to one of the injector terminals. Noticed that the bulb lit only dimmly and intermitantly. Now thinking ECU and big bucks.
One of the first things I did was check the ECU relay by applying 12 volts to (85) and (86) and checking for continuity between (30 and both
(87)'s with an analog ohmmeter. Heard a nice click
and saw the needle move so assumed it was OK.
Decided to do what was suggested and jumped
terminals (30) and (87)'s at the fuse panel. Started right up and continued running!!
I checked the relay again this time with digital ohmmeter and sure enough did not get 0 ohms.
Took the relay apart, sanded the contacts, repaced it in the car and it is running fine. Will buy new one tomorrow.
Thanks again for you help. I am happy again.
Joseph
Found good pulsing voltage at (1) at ECU. Am working alone so couldn't listen for clicks at injectors while cranking, so hooked up small bulb to one of the injector terminals. Noticed that the bulb lit only dimmly and intermitantly. Now thinking ECU and big bucks.
One of the first things I did was check the ECU relay by applying 12 volts to (85) and (86) and checking for continuity between (30 and both
(87)'s with an analog ohmmeter. Heard a nice click
and saw the needle move so assumed it was OK.
Decided to do what was suggested and jumped
terminals (30) and (87)'s at the fuse panel. Started right up and continued running!!
I checked the relay again this time with digital ohmmeter and sure enough did not get 0 ohms.
Took the relay apart, sanded the contacts, repaced it in the car and it is running fine. Will buy new one tomorrow.
Thanks again for you help. I am happy again.
Joseph
02-11-2003, 05:13 PM
#7
Burning Brakes
Aha! The $15 fuel-injection relay strikes again! Congratulations for finding the problem at last, and good news that it was so simple ( =inexpensive) in the end. Well, at least you learned a lot in the process. I'm also saving Wally's diagnostic method, that could save me a bundle of time some day.
This is way off-topic, but I recently did a "tune-up plus" on my car. I checked vacuum line and HVAC system integrity, replaced all rubber connectors in the vacuum system, replaced the air filter, spark plugs & (more importantly) wires, checked/cleaned cap & rotor, and also replaced the giant O-ring between the AFM and the throttle on my car. It is running better than I can ever remember. If you haven't done these things yet you might want to consider it since we have the same year car and it made a big difference.
Rick
This is way off-topic, but I recently did a "tune-up plus" on my car. I checked vacuum line and HVAC system integrity, replaced all rubber connectors in the vacuum system, replaced the air filter, spark plugs & (more importantly) wires, checked/cleaned cap & rotor, and also replaced the giant O-ring between the AFM and the throttle on my car. It is running better than I can ever remember. If you haven't done these things yet you might want to consider it since we have the same year car and it made a big difference.
Rick