83 928 stalled and no start
11-22-2009, 09:09 AM
#16
Race Car
This issue I see is it is running with out the relay!
It will start and idle then stall as the throttle is pressed. He had a green wire issue but corrected it then it started. If it is starting with out the relay some thing is either shorted or it is finding ground from some other source.
It will start and idle then stall as the throttle is pressed. He had a green wire issue but corrected it then it started. If it is starting with out the relay some thing is either shorted or it is finding ground from some other source.
11-22-2009, 09:26 AM
#17
Rennlist Member
I just went outside to check on how mine works.
It always energises the fuel pump for about a 1 second burst each time I turn the key to the on position.
If XVII is pulled and replaced at 30 - 87 with a jumper wire, then the fuel pump runs always, regardless of key position.
Hope this helps. Not sure what you are dealing with. I agree it sounds like a short. Know that I've worked on 4 of these cars so far and three have had various electrical shorts and melted wires in harnesses and CE. Thats why you can buy them cheap. Nobody can afford what it would cost for a mechanic to track down all the issues. If you are into that kind of thing, you will have fun. If not, sell now. Honestly. Nobody can protect your sanity better than you. Mine has left me.
It always energises the fuel pump for about a 1 second burst each time I turn the key to the on position.
If XVII is pulled and replaced at 30 - 87 with a jumper wire, then the fuel pump runs always, regardless of key position.
Hope this helps. Not sure what you are dealing with. I agree it sounds like a short. Know that I've worked on 4 of these cars so far and three have had various electrical shorts and melted wires in harnesses and CE. Thats why you can buy them cheap. Nobody can afford what it would cost for a mechanic to track down all the issues. If you are into that kind of thing, you will have fun. If not, sell now. Honestly. Nobody can protect your sanity better than you. Mine has left me.
Last edited by Landseer; 11-22-2009 at 09:46 AM.
11-22-2009, 09:52 AM
#18
Race Car
Landseer, your correct but with the FP relay removed he is still getting voltage to the pump. That indicates some type of short, this should help with testing the basics.!
11-22-2009, 10:48 AM
#21
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Hi Guys,
Its an 83 us model. Its gotta be short somewhere. I will go thru the whole car today. I will also check the terminals on the battery. The ground strap is clean.
I dont want to sell it and I wont give up. I went thru this last year with my 86 Corvette. Digital dash, bad grounds etc. A no start condition just bugs the crap out of me. Thanks for all of your help. I will report my findings at the end of the day. Take care.
Joe Flash
Its an 83 us model. Its gotta be short somewhere. I will go thru the whole car today. I will also check the terminals on the battery. The ground strap is clean.
I dont want to sell it and I wont give up. I went thru this last year with my 86 Corvette. Digital dash, bad grounds etc. A no start condition just bugs the crap out of me. Thanks for all of your help. I will report my findings at the end of the day. Take care.
Joe Flash
11-22-2009, 10:43 PM
#22
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Hi Guys,
I worked on the car for about 3 hours today and I had to work my business for the rest of the day. I removed the fuse panel and checked and cleaned each fuse, relay and contacts for corrosion. It looked pretty good. I checked the wires and all looked good. Checked the pinouts and voltage 10 & 29 going to the Jetronic and tested good. I checked all grounds on car cleaned and greased all contact grounds. I checked out the AFC relay and I get power at 30, and with ign on I get power at 86. I did not have time to complete this and need to check further. Its gotta be a short somewhere in the fuel system. Maybe a wire shorting to ground. Can a shorted fuel injector give me this problem? Thanks.
Joe Flash
I worked on the car for about 3 hours today and I had to work my business for the rest of the day. I removed the fuse panel and checked and cleaned each fuse, relay and contacts for corrosion. It looked pretty good. I checked the wires and all looked good. Checked the pinouts and voltage 10 & 29 going to the Jetronic and tested good. I checked all grounds on car cleaned and greased all contact grounds. I checked out the AFC relay and I get power at 30, and with ign on I get power at 86. I did not have time to complete this and need to check further. Its gotta be a short somewhere in the fuel system. Maybe a wire shorting to ground. Can a shorted fuel injector give me this problem? Thanks.
Joe Flash
11-22-2009, 10:49 PM
#23
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Hi All,
This is a post I found on the forum from Rich9928P,
For those of you who own US-spec 928s from 1980 - 1984, I've provided the connector to the J-Jet controller pin description.
If you're having starting problems, this information could help.
This is how the system works. AFC [Air Fuel Control] relay XVI pin 30 always has 12 Volts regardless of ignition switch position. The AFC relay switches between pins 30 and 87, and the 12V at pin 87 then goes to the fuel injectors.
a. Measure voltage at pin 30?
-- If 12V present, next (for all test cases below, have the ignition turned on) is there 12V at pin 87? If yes go to (b)
-- If no, check the connection at the battery. A direct cable connects the battery to the AFC relay pin 30. Is there 12V at AFC relay pin 85? If there is no voltage, the ignition switch could be bad or the path between the ignition switch and AFC relay has an open or short circuit.
b) is there 12V at the fuel injectors (pick any one to check)?
-- If yes, this says that your problem could be with the fuel injection "ground" path. Go to (c)
-- if no, there is a wiring problem between the AFC relay and fuel injectors.
note: it may be confusing to see 12 V at both sides of the fuel injectors. The reason is when the engine isn't running, the circuit is open from the L-Jet module pins to ground. So with very little current flowing there is no voltage drop across the fuel injectors.
c) is there 12V at L-Jet connector pin 10 and 29?
-- if no, there is a wiring problem between AFC relay pin 87 and L-Jet connector pin 10 and 29.
-- If yes, check grounds for the L-jet controller. L-Jet connector pins 5, 16, 17 and 35 should have a very low resistance (via ohm check) to ground. For this check, set your VOM to Ohm mode and measure the resistance between the L-Jet connectors and a ground point on the car. If the Ohm reading is high to infinite, there is a wiring or connector problem with the ground points.
If all tests show OK, the L-Jet could be bad.
L-Jets are pretty reliable systems. As with any other system, the majority of problems in no-start or hard start situations are bad or non-existant signals from sensors or no voltage due to relays.
I have a feeling my problem lies here.
Joe
This is a post I found on the forum from Rich9928P,
For those of you who own US-spec 928s from 1980 - 1984, I've provided the connector to the J-Jet controller pin description.
If you're having starting problems, this information could help.
This is how the system works. AFC [Air Fuel Control] relay XVI pin 30 always has 12 Volts regardless of ignition switch position. The AFC relay switches between pins 30 and 87, and the 12V at pin 87 then goes to the fuel injectors.
a. Measure voltage at pin 30?
-- If 12V present, next (for all test cases below, have the ignition turned on) is there 12V at pin 87? If yes go to (b)
-- If no, check the connection at the battery. A direct cable connects the battery to the AFC relay pin 30. Is there 12V at AFC relay pin 85? If there is no voltage, the ignition switch could be bad or the path between the ignition switch and AFC relay has an open or short circuit.
b) is there 12V at the fuel injectors (pick any one to check)?
-- If yes, this says that your problem could be with the fuel injection "ground" path. Go to (c)
-- if no, there is a wiring problem between the AFC relay and fuel injectors.
note: it may be confusing to see 12 V at both sides of the fuel injectors. The reason is when the engine isn't running, the circuit is open from the L-Jet module pins to ground. So with very little current flowing there is no voltage drop across the fuel injectors.
c) is there 12V at L-Jet connector pin 10 and 29?
-- if no, there is a wiring problem between AFC relay pin 87 and L-Jet connector pin 10 and 29.
-- If yes, check grounds for the L-jet controller. L-Jet connector pins 5, 16, 17 and 35 should have a very low resistance (via ohm check) to ground. For this check, set your VOM to Ohm mode and measure the resistance between the L-Jet connectors and a ground point on the car. If the Ohm reading is high to infinite, there is a wiring or connector problem with the ground points.
If all tests show OK, the L-Jet could be bad.
L-Jets are pretty reliable systems. As with any other system, the majority of problems in no-start or hard start situations are bad or non-existant signals from sensors or no voltage due to relays.
I have a feeling my problem lies here.
Joe
11-23-2009, 08:31 PM
#25
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Hi All,
Ok. Worked on the car all day. I did not gain much ground but found different symptoms of the problem.
1. Car starts without fuel pump relay. If I plug in relay or jumper wire while running car will stall.
If I jump 30 to 87 or any other slot car tach will go crazy and car will stall.
Fuel pump will energize continuously when jumpered 30-87 but will not start.
Car runs for two or three minutes then wants to stall.
If I jump the fuel pump 30 to 87 briefly car will continue to run, because I am energizing the fuel pump to push the fuel up to the injectors.
Car will also start now when warm but without relay.
With the relay in, the fuel pump will only energize after I turn the starter. Wont start though.
Disconnected oxygen sensor, no change.
Cleaned all grounds.
I removed fuel pump. Looks like a new Blue Bosch fuel pump. I bench tested fuel pump and it pumps like crazy and very quiet. Fuel pump pressure is 39. But when the car stalled (ran out of fuel) after 2 minutes there was no fuel at the test rail.
I get power at fuel pump when crank and no start, but no power at fuel pump when car is running.
Checked grounds at L-Jetronic:
Ohms
Pin # 5 5.0 ohms
Pin # 16 .4 ohms
Pin # 17 .4 ohms
Pin # 35 .4 ohms
Pin # 5 seemed a little high on the ohms.
Power at Pun # 10 and 29
I jumped the cold start valve noi change. I jumped the temp 2 sensor, no change.
Voltage check on all injectors. 12v on both sides of each injector.
This is without the AFC intake unit installed.
The problem is the fuel pump will not run with the fuel relay installed and starting the car.
The fuel pump needs to continuously run when the car is started. It will not. I dont know how the car is running without the operation of the fuel pump. I give it gas and race the engine and it feels smooth and wont bog while at idle.
My question is, what controls the operation of the fuel pump? Also, when does the fuel pump energize? When you turn the key like American cars, or after you crank the starter?
Thanks,
Joe Flash
Ok. Worked on the car all day. I did not gain much ground but found different symptoms of the problem.
1. Car starts without fuel pump relay. If I plug in relay or jumper wire while running car will stall.
If I jump 30 to 87 or any other slot car tach will go crazy and car will stall.
Fuel pump will energize continuously when jumpered 30-87 but will not start.
Car runs for two or three minutes then wants to stall.
If I jump the fuel pump 30 to 87 briefly car will continue to run, because I am energizing the fuel pump to push the fuel up to the injectors.
Car will also start now when warm but without relay.
With the relay in, the fuel pump will only energize after I turn the starter. Wont start though.
Disconnected oxygen sensor, no change.
Cleaned all grounds.
I removed fuel pump. Looks like a new Blue Bosch fuel pump. I bench tested fuel pump and it pumps like crazy and very quiet. Fuel pump pressure is 39. But when the car stalled (ran out of fuel) after 2 minutes there was no fuel at the test rail.
I get power at fuel pump when crank and no start, but no power at fuel pump when car is running.
Checked grounds at L-Jetronic:
Ohms
Pin # 5 5.0 ohms
Pin # 16 .4 ohms
Pin # 17 .4 ohms
Pin # 35 .4 ohms
Pin # 5 seemed a little high on the ohms.
Power at Pun # 10 and 29
I jumped the cold start valve noi change. I jumped the temp 2 sensor, no change.
Voltage check on all injectors. 12v on both sides of each injector.
This is without the AFC intake unit installed.
The problem is the fuel pump will not run with the fuel relay installed and starting the car.
The fuel pump needs to continuously run when the car is started. It will not. I dont know how the car is running without the operation of the fuel pump. I give it gas and race the engine and it feels smooth and wont bog while at idle.
My question is, what controls the operation of the fuel pump? Also, when does the fuel pump energize? When you turn the key like American cars, or after you crank the starter?
Thanks,
Joe Flash
11-23-2009, 10:53 PM
#26
Race Car
Don't want to get you off track but!
You should not be loosing fuel pressure that quickly. There is a one way valve connected to the fuel pump, is your return fuel line blocked. Have you checked the FP Reg and dampeners. They should hold a vacuum and no gas in the vacuum lines when removed. Your injectors could be leaking down but two minutes is way to short. Your injectors are batch fired by the computer it provides a pulsed ground.
You should not be loosing fuel pressure that quickly. There is a one way valve connected to the fuel pump, is your return fuel line blocked. Have you checked the FP Reg and dampeners. They should hold a vacuum and no gas in the vacuum lines when removed. Your injectors could be leaking down but two minutes is way to short. Your injectors are batch fired by the computer it provides a pulsed ground.
11-23-2009, 10:56 PM
#27
Race Car
Have you checked your 14 pin connector near the hot post, is it clean no wires have been mixed up if you had it apart 
Hate to bring up the green wire again but!!
Hate to bring up the green wire again but!!
11-23-2009, 11:02 PM
#28
Rennlist Member
Does this car have a factory alarm?
Workshop manual page 90-47 says that a defect in the alarm control unit could cause failure of ignition or fuel pump under
"certain circumstances".
To bridge it, pull off plug Z on central electric board and bridge terminals 1 and 6 on the CE.
"This will stop the function of the alarm", says the WSM.
Might as well take that out of the mix. Be careful selecting the right electrodes to bridge.
Mine is an 84, and the alarm system changed for the 84 model year. But for 83 and 82 I think it is the same. The WSM version I'm using is dated '82 volume V Body, Electrics of the 6 volume set.
Workshop manual page 90-47 says that a defect in the alarm control unit could cause failure of ignition or fuel pump under
"certain circumstances".
To bridge it, pull off plug Z on central electric board and bridge terminals 1 and 6 on the CE.
"This will stop the function of the alarm", says the WSM.
Might as well take that out of the mix. Be careful selecting the right electrodes to bridge.
Mine is an 84, and the alarm system changed for the 84 model year. But for 83 and 82 I think it is the same. The WSM version I'm using is dated '82 volume V Body, Electrics of the 6 volume set.
11-23-2009, 11:19 PM
#29
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Hi Mark,
Yeah, I just did a massive search on this forum about the green wire. In some areas my wire is brown, but it is not deteriorated.I learned that the green wire also sends a ground signal to the fp relay to energize the fuel pump. Aha. Almost everything on that car is original. My fuel pump relay has a date of 1-03-83. I will order a new green wire. I have a new fuel pump relay on the way too. I dont like to guess and just replace parts. That is not a good troubleshooting tactic. I am trying as hard as I can to diagnois this problem and I have put many hours in with this car. Although, I have learned a lot of where mostly everything is located. Geez, you have to check almost everything on these cars.
I have not removed the 14 pin connector. I will check the fuel pressure regulators and my return line tomorrow. I do have a broken fuel vent line at the canister. The pressure stays in the line most of the time. The car would run longer than 2 minutes, but it starts to run rich and burns my eyes so I shut it off. But how can the car run without the fuel pump running? There is no power to the fuel pump when the car is running without the fp relay. Got me baffled.
Joe Flash
Yeah, I just did a massive search on this forum about the green wire. In some areas my wire is brown, but it is not deteriorated.I learned that the green wire also sends a ground signal to the fp relay to energize the fuel pump. Aha. Almost everything on that car is original. My fuel pump relay has a date of 1-03-83. I will order a new green wire. I have a new fuel pump relay on the way too. I dont like to guess and just replace parts. That is not a good troubleshooting tactic. I am trying as hard as I can to diagnois this problem and I have put many hours in with this car. Although, I have learned a lot of where mostly everything is located. Geez, you have to check almost everything on these cars.
I have not removed the 14 pin connector. I will check the fuel pressure regulators and my return line tomorrow. I do have a broken fuel vent line at the canister. The pressure stays in the line most of the time. The car would run longer than 2 minutes, but it starts to run rich and burns my eyes so I shut it off. But how can the car run without the fuel pump running? There is no power to the fuel pump when the car is running without the fp relay. Got me baffled.
Joe Flash
11-23-2009, 11:31 PM
#30
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Hi Landseer,
The car has an aftermarket alarm with a remote. It seems to be functioning properly. Below is a picture of my circuit board. The FP relay is not plugged in. I removed and cleaned all contacts. It looked very good with minor corrosion. Is there a relay missing for the factory alarm? Also. how would I know if the factory alarm is active? Thanks.
Joe Flash
The car has an aftermarket alarm with a remote. It seems to be functioning properly. Below is a picture of my circuit board. The FP relay is not plugged in. I removed and cleaned all contacts. It looked very good with minor corrosion. Is there a relay missing for the factory alarm? Also. how would I know if the factory alarm is active? Thanks.
Joe Flash