83 928 stalled and no start
11-23-2009, 11:31 PM
#31
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Its kind of crazy. Plus, the wiring diagrams and descriptions in manuals are cryptic.
Things that might/might not help:
Alarm is designed to disable fuel pump relay.
At 6300 rpm, the relay also is disabled.
The only way I could envision the car could run (albeit low rpm) is if the vaccum system on the dampers and / or fuel regulator is sucking fuel through a broken diaphram into the throttle body.
Does this car have a second fuel pump? Weren't some supposed to have a second pump, depending on location sold, ie, high altitude? Thought I read that here somewhere / can't quote a source.
Keep the faith, solve this.
Things that might/might not help:
Alarm is designed to disable fuel pump relay.
At 6300 rpm, the relay also is disabled.
The only way I could envision the car could run (albeit low rpm) is if the vaccum system on the dampers and / or fuel regulator is sucking fuel through a broken diaphram into the throttle body.
Does this car have a second fuel pump? Weren't some supposed to have a second pump, depending on location sold, ie, high altitude? Thought I read that here somewhere / can't quote a source.
Keep the faith, solve this.
11-23-2009, 11:38 PM
#32
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83 didn't have the alarm relay in position IV. That happened in 84. 83 looks like its controlled by the alarm controller box, which I think is buried in the dash up above the glove box. If it doesn;t have the factory alarm, its supposed to already have a bridge circuit like the one mentioned above, Z1 to Z6. Alarm is supposed to interrupt either ignition or fuel pump or both. Depends on year and market sold into. Lots of reading in manuals needed to get the facts on this. You really need the CD manuals and especially ancilliary tech papers --- contact Rog100. I can't research fast enough on this to answer your questions I'm afraid, and am just a layman.
Aftermarket alarm could be a problem.
Aftermarket alarm could be a problem.
11-24-2009, 12:18 AM
#33
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I still can't figure-out why you can't bridge 87 and 30 on the fuel pump relay to get the fuel pump to run. That doesn't make sense to me. Nothing should interupt that, other than fuse in that circuit. Somebody has done something to your setup.
I can't give you a comprehensive overview of what controls the fuel pump entirely, but am learning and working through it.
The L-Jetronic has a more interconnectivity with the fuel pump:
I think this explains why I get an initial burst of fuel pump on moving key to on position. If I don't move it further to start, the AFM safety feature kicks-in and stops my fuel pump (no air flow, no barn door swing, tells Jetronic to shut-down pump).
I can't give you a comprehensive overview of what controls the fuel pump entirely, but am learning and working through it.
The L-Jetronic has a more interconnectivity with the fuel pump:
I think this explains why I get an initial burst of fuel pump on moving key to on position. If I don't move it further to start, the AFM safety feature kicks-in and stops my fuel pump (no air flow, no barn door swing, tells Jetronic to shut-down pump).
Last edited by Landseer; 06-17-2011 at 03:11 AM.
11-24-2009, 12:35 AM
#34
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Hi Landseer,
The fuel pump will run when I connect 30 and 87, but I just cant start the car that way. Car has one fuel pump. Somebody was working on that car because when I went to clean the ground points. Someone did that and all the ground points were cleaned. The car was running great for a month. I just drove it around my industrial complex. As soon as I got it registered and drove it for one day, it crapped out on me.
I have the 9 volume Porsche repair manuals and I am still stumped. I have been reading them constantly. But I will find out the problem. There is a section for the alarm system. I will read thru it tomorrow. But, what has helped me out a lot is the info from forum members like yourselves. I appreciate your help. Take care.
Joe Flash
The fuel pump will run when I connect 30 and 87, but I just cant start the car that way. Car has one fuel pump. Somebody was working on that car because when I went to clean the ground points. Someone did that and all the ground points were cleaned. The car was running great for a month. I just drove it around my industrial complex. As soon as I got it registered and drove it for one day, it crapped out on me.
I have the 9 volume Porsche repair manuals and I am still stumped. I have been reading them constantly. But I will find out the problem. There is a section for the alarm system. I will read thru it tomorrow. But, what has helped me out a lot is the info from forum members like yourselves. I appreciate your help. Take care.
Joe Flash
11-24-2009, 01:34 AM
#35
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OK. Did you try jumpering 30 and 87 on the fuel pump relay, plus, make up a three-way jumper and jump 30 to 87 to 87A on the AFC relay? Really, that's worked for
me more than once.
The sensors fail on these cars and so do relays, sometimes intermittently. I was loosing my AFC relay intermittently when temperatures hit single digits here in Richmond. Would miss while driving, then cut out. Thankfully, I had a three way jumper in the glove compartment. Don't leave home without it.
Temp/time sensor is notorius to cause no-start on the 84. Dealer parts guy told me "yeah, I used to sell lots of them back in the day"
And, as you can see, a massive air leak due to a boot letting go or bad AFM O ring / AFM not in the right position, or broken hose at base of Throttle body means no AFM movement, which means fuel pump cuts out. You can jam the AFM door open with a piece of heater hose.
Ignition switch failure is very common on these cars. That can be a problem in that low voltage is insufficient to trigger relays
Throwing new electrical parts at these cars is never too bad an idea, though its a bit of a cop out..
Again, keep up the good work.
me more than once.
The sensors fail on these cars and so do relays, sometimes intermittently. I was loosing my AFC relay intermittently when temperatures hit single digits here in Richmond. Would miss while driving, then cut out. Thankfully, I had a three way jumper in the glove compartment. Don't leave home without it.
Temp/time sensor is notorius to cause no-start on the 84. Dealer parts guy told me "yeah, I used to sell lots of them back in the day"
And, as you can see, a massive air leak due to a boot letting go or bad AFM O ring / AFM not in the right position, or broken hose at base of Throttle body means no AFM movement, which means fuel pump cuts out. You can jam the AFM door open with a piece of heater hose.
Ignition switch failure is very common on these cars. That can be a problem in that low voltage is insufficient to trigger relays
Throwing new electrical parts at these cars is never too bad an idea, though its a bit of a cop out..
Again, keep up the good work.
11-24-2009, 10:56 PM
#37
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Hi Stephen,
I tried using your fuel pump relay and it makes a clicking as I start the engine. Not the right one. I have a new fuel pump relay on its way to me. I believe I have a wiring problem. I dont think the green wire would screw up the fuel pump relay circuit. The car should start with the relay, and should not die when I jump 30 to 87 or install the relay. Even if the relay were bad. The wiring circuit is screwed up for the fuel pump and/or fuel pump relay. What a friggin electrical nightmare. I will keep you posted.
Joe Flash
I tried using your fuel pump relay and it makes a clicking as I start the engine. Not the right one. I have a new fuel pump relay on its way to me. I believe I have a wiring problem. I dont think the green wire would screw up the fuel pump relay circuit. The car should start with the relay, and should not die when I jump 30 to 87 or install the relay. Even if the relay were bad. The wiring circuit is screwed up for the fuel pump and/or fuel pump relay. What a friggin electrical nightmare. I will keep you posted.
Joe Flash
11-24-2009, 10:59 PM
#38
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Did you jump the AFC as suggested?
Also, the green wire can mess-up the fuel pump.
It can cause the L Jetronic to believe the tach rpm is >6300 and prevent the relay from operating.
Patience. You will win. It will be worth it.
Also, the green wire can mess-up the fuel pump.
It can cause the L Jetronic to believe the tach rpm is >6300 and prevent the relay from operating.
Patience. You will win. It will be worth it.
11-25-2009, 10:57 AM
#39
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The connector to the green wire is cracked but the connection looks good. I am refering to the connection that is going away from the Dist. by the firewall. Could that be a issue?
Stephen
Stephen
11-26-2009, 01:08 AM
#40
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Hi All,
Update. I plugged in the old fuel pump relay and the afc and tried to start it. It starts runs a few seconds then quits. After 2 attempts I will have to wait a minute to start a few seconds again. I ordered a new green ignition wire and should have it next week. The plug broke apart when I removed it from the distributor. Very dry and brittle. I used my ohm meter with the continuity alarm. I checked each wire and wiggled it around and did not find any of the 2 wires broken. It would be nice if it was the green wire. But with my luck, probably not.
Before, the car would not even run with the relay. My 928 shows different problems every day. Like a crazy broad playing head games. How nice. BTW. I put a test light on the + pos side of the fuel pump. When the car does run for 3-4 seconds the fuel pump is pumping. I have spark and fuel. I am either losing fuel at the injectors or losing spark signal. Dont think its fuel because of fuel pressure (39) and + 12v on both sides of injectors and I hear them working.
Well I think I will take a break on the car until the parts come in next week. At least I can drive my vette for now. Happy Thanksgiving All.
Joe Flash
Update. I plugged in the old fuel pump relay and the afc and tried to start it. It starts runs a few seconds then quits. After 2 attempts I will have to wait a minute to start a few seconds again. I ordered a new green ignition wire and should have it next week. The plug broke apart when I removed it from the distributor. Very dry and brittle. I used my ohm meter with the continuity alarm. I checked each wire and wiggled it around and did not find any of the 2 wires broken. It would be nice if it was the green wire. But with my luck, probably not.
Before, the car would not even run with the relay. My 928 shows different problems every day. Like a crazy broad playing head games. How nice. BTW. I put a test light on the + pos side of the fuel pump. When the car does run for 3-4 seconds the fuel pump is pumping. I have spark and fuel. I am either losing fuel at the injectors or losing spark signal. Dont think its fuel because of fuel pressure (39) and + 12v on both sides of injectors and I hear them working.
Well I think I will take a break on the car until the parts come in next week. At least I can drive my vette for now. Happy Thanksgiving All.
Joe Flash
Last edited by flash porsche; 11-26-2009 at 07:24 PM.
12-01-2009, 08:51 PM
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Hi All,
Well I installed the new green wire in the distributor and a new fuel pump relay. Car will not start. I dont know what to do anymore. I am almost ready to take an axe to it. I have over 30 hours of troubleshooting this car. This car has too many electrical components that fail. I have troubleshooted and fixed many American cars in my life and I know what I am doing. But this car is the Devil from Germany. Sorry, just VENTING. Its back to the drawing board.
Joe Flash
Well I installed the new green wire in the distributor and a new fuel pump relay. Car will not start. I dont know what to do anymore. I am almost ready to take an axe to it. I have over 30 hours of troubleshooting this car. This car has too many electrical components that fail. I have troubleshooted and fixed many American cars in my life and I know what I am doing. But this car is the Devil from Germany. Sorry, just VENTING. Its back to the drawing board.
Joe Flash
Last edited by flash porsche; 12-01-2009 at 09:45 PM.
12-01-2009, 09:26 PM
#43
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Well, you said a few posts above you had ordered the green wire. Best to replace anyhow if the ends were cracked.
Does it run if you take a piece of hose and hold the AFM in the open position when you try to start it? (careful not to ingest something foreign). If yes, then there is likely air leak in the intake and the door isn't opening-up enough to prevent safety shut down that interrupts the signal to the coil on the fuel pump relay.
Also,
Does it run with the three way jumper on the ignition relay and the jumper on the fuel pump relay?
I went through this crazy excercise with my first one. Can't answer all the complicated interlock questions but I'll continue to give you the things that worked for me if you want.
Does it run if you take a piece of hose and hold the AFM in the open position when you try to start it? (careful not to ingest something foreign). If yes, then there is likely air leak in the intake and the door isn't opening-up enough to prevent safety shut down that interrupts the signal to the coil on the fuel pump relay.
Also,
Does it run with the three way jumper on the ignition relay and the jumper on the fuel pump relay?
I went through this crazy excercise with my first one. Can't answer all the complicated interlock questions but I'll continue to give you the things that worked for me if you want.
12-01-2009, 09:44 PM
#44
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Hi Landseer,
How do I jump The ignition? Do you mean the AFM relay? Can you tell me what the 3 way jumper points are for the fuel pump and ignition relay? I thought about what you said earlier:
Ignition switch failure is very common on these cars. That can be a problem in that low voltage is insufficient to trigger relays.
I did put a hose in the afm to hold the door open, and it did not start. It wont run with the fuel pump relay jumper. I only hear the fuel pump energize when I try and start it. Not when I turn the key to on. I also jumped the afm relay only two wire jump on afm and fuel pump relay and still no start. I only worked on the car for a half an hour today, because I had to work my business. I am getting kinda tired of pushing it in and out of my shop. Thats a heavy little sucker. Thanks.
How do I jump The ignition? Do you mean the AFM relay? Can you tell me what the 3 way jumper points are for the fuel pump and ignition relay? I thought about what you said earlier:
Ignition switch failure is very common on these cars. That can be a problem in that low voltage is insufficient to trigger relays.
I did put a hose in the afm to hold the door open, and it did not start. It wont run with the fuel pump relay jumper. I only hear the fuel pump energize when I try and start it. Not when I turn the key to on. I also jumped the afm relay only two wire jump on afm and fuel pump relay and still no start. I only worked on the car for a half an hour today, because I had to work my business. I am getting kinda tired of pushing it in and out of my shop. Thats a heavy little sucker. Thanks.
Last edited by flash porsche; 12-01-2009 at 10:04 PM.
12-01-2009, 10:59 PM
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Hi Landseer,
I just read your previous post. Yes, I definately needed the green wire and I am not complaining about buying it. Only cost me 88 bucks wholesale. I missed the electronic ignition relay. I have a pic and I know now. I will test further tomorrow.
Thanks Lanseer for your help.
Joe Flash
I just read your previous post. Yes, I definately needed the green wire and I am not complaining about buying it. Only cost me 88 bucks wholesale. I missed the electronic ignition relay. I have a pic and I know now. I will test further tomorrow.
Thanks Lanseer for your help.
Joe Flash