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Car starting and immediately stalling

Hi all,

Iím having an issue with my 1983 Porsche 928S. I left my car stand still over the holidays, when I came back I turned the key and it started a few times without an issue. This one time, I revved the engine and it stalled on me. Ever since then I have not been able to start my vehicle. It starts and immediately stalls, I used to hear a clicking sound each time I turned the ignition on, I always thought it was the fuel pump but I may be wrong with my assumption. The sound seemed to have come from behind the dash by the fuse box. Well I donít hear the clicking noise anymore and my car wonít run more than a second. I put about a gallon of gas thinking it has run out of it but that doesnít seem to remediate the issue.

My next steps are to replace the fuel filter.
Perhaps replace the fuel pump relay.
Replace fuel pump altogether is need be.

Any ideas, or any troubleshooting you guys recommend me doing?

Old 01-27-2015, 04:22 PM
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thats the first thing to check is the fuel pump situation. how do the plugs look?
Old 01-27-2015, 07:04 PM
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the clicking sounds like your relay(fuel pump relay). jump the relay to see if anything changes
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Old 01-27-2015, 08:43 PM
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Replace the thermo time switch. It looks like a temp sensor, located near the front of the water bridge. It is the only one on the front of the engine that is mounted axially so you can't miss it.

When the weather gets cool, the thermo time switch controls the cold start injector.

I had to replace these on both my 84 USA, cars which were behaving exactly as you describe.
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Old 01-28-2015, 02:21 AM
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I live in Las Vegas, we don't get too much cold weather around here. Not the cheapest solution either! I will try jumping the relay, checking the spark plugs and also looking at the thermo time switch as well. Any other ideas or troubleshooting steps are welcomed.

Landseer, did you replace anything else when you ran into this issue?
Old 01-28-2015, 09:06 AM
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If it starts then stalls, the cold start injector is working. The problem is that the rest of the injectors are not opening to allow the engine to continue running.

The problem I encountered was the ground for the injector controller was loose. It's located under the supplemental air valve located on the passenger-side valve cover. The ground wire (brown) is essentially hidden. I discovered my loose ground by spraying in a buttload of starting fluid into the intake, and as it idled I laid my hand on the valve and the engine instantly stalled. My best answer was to re-locate the ground to the forward screw hole in the same valve cover. I added more wire to reach the hole. After I did this I never had another problem with the injectors not opening.
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Old 01-30-2015, 04:08 PM
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This brings back Memories , Had also a Similar condition as you described :
" Ever since then I have not been able to start my vehicle. It starts and immediately stalls "
I suggest you jump the " Fuel Injection Relay " check on it but I think jump 30 to 87 polls
or just try another relay . This would be the first thing I would check for sure
I am in Las Vegas also but at my Mendocino Coast home just now or you
could try my relay . Not sure of my return dates but could help you trouble shoot it .
This is exactly what they do when the Injection Relay fails : Starts on cold start valve
then the Injection relay takes over the fuel delivery " get it "
hope that helps Note : the Fuel Injection Relay is different then the fuel pump relay

Last edited by aluminum; 01-30-2015 at 06:35 PM..
Old 01-30-2015, 06:19 PM
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Quote:
Originally Posted by aluminum View Post
This brings back Memories , Had also a Similar condition as you described :
" Ever since then I have not been able to start my vehicle. It starts and immediately stalls "
I suggest you jump the " Fuel Injection Relay " check on it but I think jump 30 to 87 polls
or just try another relay . This would be the first thing I would check for sure
I am in Las Vegas also but at my Mendocino Coast home just now or you
could try my relay . Not sure of my return dates but could help you trouble shoot it .
This is exactly what they do when the Injection Relay fails : Starts on cold start valve
then the Injection relay takes over the fuel delivery " get it "
hope that helps Note : the Fuel Injection Relay is different then the fuel pump relay
^^^
Classic symptom of the fuel injection relay failure, try jumping the pins 30 to 87 as suggested, or just replace relay XVI ( 16) 928.615.119.01 - its the only one of that type on the panel, so you can't swap in any other.
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Old 01-31-2015, 01:25 PM
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If thermo time fails it misapplies cold start injector, so wrong again maleficio. Classic failure. Regarding injector relay, it must be jumpered with a three ended wire, as 30 must tie to both 87 terminals (there are two).

Another ljet failure, though seemingly unusual, that will give this start/stall symptom is loss of one of the two final stage amps. This happened to my 84 car this summer. What happens is only four injectors fire. It can be diagnosed with a noid light. Mine ended up caused by a corroded wire connection that was corroded just inside the cover of the brain box. ( I removed the cover in desperation, having traced the failure to the brain through a ten hour process of elimination alongside the road in Virginia Beach. Cleaning that wire connection solved it.

Btw, replace all the sensors, temp 2 and thermo time especially.

Good point on cleaning the grounds. For ljet cars the grounds most critical are located on pass side cam cover. One is buried beneath the valve in the blue hose leading from the air pump. Remove that valve for access to that hidden ground. With these cars don't waste your time looking for exactly what is wrong, instead do all the things suggested here as they are all proven maintenance issues and solutions, often overlapping due to car age.
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Last edited by Landseer; 01-31-2015 at 03:25 PM..
Old 01-31-2015, 03:19 PM
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Update:
I replaced the Fuel Injector Relay and the Fuel Pump Relay with no success.
I checked the brown ground wire that someone had suggested as well the car still reacts the same. When it's left to sit for a while it starts, runs for about a second and then immediately stalls.

I checked the fuel pump, I can hear the spark on the fuel pump when I turn it on. It leaks a drop or two each time I turn the key. I'm thinking of replacing the Fuel Filter next since it's the next cost effective fix.
Old 02-09-2015, 04:11 PM
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This might be way out there in left field, but I am going to tell you anyway. I have a '79. Someone who owned the car before me must have had a problem with the ignition switch because the car cannot be started with turning the key to the start position. It still can be placed in the different positions, however, there is no spring back action when you go to start it. They solved the problem by adding a push button start and to this day I have never traced where they go. I actually kind of like the push button start so I have left it alone. I still have to put the key in the run position before I hit the push button start. Here is the thing. If I forget to put it in the run position or if I don't have it turned far enough, the car will start for a second and turn off. I can do this in the off position or radio position(?), or with the key completely out. The car will start for a second and then die. I can do this multiple times. It sounds very similar to what you are describing. Then I put it in the run position and the car starts right up. I have no way to tell if what goes on with my car is similar to yours, but hopefully it will give you or someone else trying to help some ideas. It may something going on with the ignition switch. I find it amazing that my car would start at all like this but it does and just for a second. Hope this helps.
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Old 02-09-2015, 05:10 PM
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Also read somewhere about the small screen on the inlet side of the fuel distributor might be clogged.
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Old 02-09-2015, 05:29 PM
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Quote:
Originally Posted by Rupesy View Post
Also read somewhere about the small screen on the inlet side of the fuel distributor might be clogged.
Not on an 83, no fuel distributor.
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Old 02-10-2015, 06:09 AM
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Quote:
Originally Posted by Juan Porsche View Post
Update:
I replaced the Fuel Injector Relay and the Fuel Pump Relay with no success.
I checked the brown ground wire that someone had suggested as well the car still reacts the same. When it's left to sit for a while it starts, runs for about a second and then immediately stalls.

I checked the fuel pump, I can hear the spark on the fuel pump when I turn it on. It leaks a drop or two each time I turn the key. I'm thinking of replacing the Fuel Filter next since it's the next cost effective fix.

Have you tried spraying a good bit of starting fluid into the intake yet? That was how I found my problem. If your engine will light off and idle until the fluid is consumed, then that will tell you that the ignition side is solid, and that you do not have fuel pressure.

I bought a fuel injector noid to verify that my injectors were pulsing. They were not. Once I locked down the ground wire for the injector computer everything came back to life. I know you checked that ground point, but did you also verify the ground wire itself with a digital multimeter? You may have a break somewhere in the run from the computer to the ground point.

Just try with starting fluid to help you divide the problem into two sides: ignition or fuel.
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Old 02-10-2015, 11:11 AM
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Landseer said that I'm "wrong again", but what you described sounds exactly like what I dealt with. I could get three or four explosions with every crank, but the engine would stall out as soon as the fuel from the cold start valve would stop flowing. The cold start valve operates off battery power.
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Old 02-10-2015, 11:18 AM
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Using starting fluid needs some caution, it can boom, and it also can fire on a very weak spark, so its not a certainty all is well with the spark, but makes it more likely.
Old 02-10-2015, 03:17 PM
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Quote:
Originally Posted by Juan Porsche View Post
Update:
I replaced the Fuel Injector Relay and the Fuel Pump Relay with no success.
I checked the brown ground wire that someone had suggested as well the car still reacts the same. When it's left to sit for a while it starts, runs for about a second and then immediately stalls.

I checked the fuel pump, I can hear the spark on the fuel pump when I turn it on. It leaks a drop or two each time I turn the key. I'm thinking of replacing the Fuel Filter next since it's the next cost effective fix.
Food for thought :
Pull the fuse panel / Relay board loose ( Unbolt it ) and inspect the back side of the board for Green color Corrosion . This is a indication of poor connection of your wiring . Your relays plug into Prongs / posts that is hooked to the wire . The Relay Socket itself often get the Green Corrosion you can see from the front side of the panel.
If found all of it needs to be cleaned up completely . You could have a good relay but a bad connection so the injectors get no Signal / Power .

To spray some Starting fluid on to the air filter itself ( the motor when working well run on this fluid ) before starting well tell you most often if you have a Fuel Delivery problem or not . IE: if the motor runs longer until the starting fluid is used up before is stalls then Its a fuel Delivery Problem . Not a good Idea to try to keep the car going by spraying fluid to keep it running Don't ! , just spray the filter before starting .

Get a fuel Pressure Test Gauge ( may be able to use one from Auto Zone for free ) and test your fuel Pressure at some point on the fuel Rail . I forget the exact amount but should be about 29 Lbs with the Key on . You need this pressure to the Injectors . Can someone chime in of the correct fuel pressure for the 928 I know on my Mercedes Its 29 Lbs + or - and it hits that running or just Key on.

Fuel Damper : A bad fuel Damper (Pressure Regulator I think you have 2 rear of motor ) well also give your symptoms as described , Check pressure in and out ( use line wrenches ) , a bad one well cut the pressure down rather the Dampening the flow . Sometimes the car well start and die or start and run ( barely ) at idle only and not pick up .
Ignition Starting Switch : Place a jumper wire from the hot post ( pin connector Pass side front front under hood ) to the hot side of the coil , Crank the motor with the Key Start if the car run's with jumper then the switch is bad inside ( a Common Problem ).
Ballasts:
Check Power flow through the Ballasts I think you have 2 like my 1980 and be careful they get hot and well burn you ( Drivers side fender well front )

Return to Vegas is delayed still

Last edited by aluminum; 02-10-2015 at 11:18 PM..
Old 02-10-2015, 11:01 PM
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Answer?

Did this get resolved? My baby just started with same symptom and I was hoping to start with the solution first.
Old 10-02-2016, 07:17 PM
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Start & Stop

Juan,
I went through similar symptoms, together with an occasional no run at all. Checked all the usual items, including; green wire, ignition switch, etc. I did already have a fuel pressure gauge installed, so I was sure of good pressure. Even swapped out the computer.
Turned out to be the fuel injection relay. Must of had some bad contacts. Have not had any problems since.
Best of luck !!!
Old 10-03-2016, 01:07 PM
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Had the same issue with my '84. Turned out to be the fuel injection relay that was operating intermittently, which made diagnosis difficult. When the issue arose, I discovered it by placing a finger on the relay while turning on the ignition then feeling and hearing no click. Now I keep spare relays in the glovebox so I don't become stranded.

Old 10-07-2016, 08:39 AM
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