Ongoing Starting, random shut down problem
 

I have been dealing with a random no-start problem since December and today I have found a symptom that seems meaningful and I would hope someone on here could comment on it.

Background, randomly I could be cruising along at highway speeds and the car would just shut down as if fuel or electric was cut off to engine. On attempted restart the car would crank, but would not start. When it finally does, often 1/2 hour latter, the would be a large cloud of smoke as if the engine had been flooded.

In an attempt to solve the problem, I have to-date:

1. replaced the fuel pump and fuel injector relays
2. replaced the green wire
3. replaced the injector control computer with a used and tested one.
4. Installed a pressure gauge in the fuel rail.

Today I found what I hope is a meaningful symptom that can lead to solving my problem. I drove the car about 10 miles yesterday and all was fine. This AM the car would not start, i.e. cranks and sounds like it is starting, but just does not run. Over 4-5 minutes of this effort I would get a big cloud of smoke, ie unburned fuel, but no start. After giving up, I jumped out and noticed that the fuel pressure gauge had dropped to 0. I had installed the gauge about a month ago and observed that it regularly showed 28-32 psi and on shutdown the pressure would remain above 20 psi after 1/2 hour of shutdown. I noticed that I could crank the engine and pressure would come up to 32, but would drop to 0 in less than a minute (engine was off).

I had been leaning towards the idea that my problem was electrical with some ground wire issue or perhaps a bad contact somewhere, i.e. ignition switch. That said, the fuel pressure drop seems to be significant bit of info and I thought I would ask what some of the experts here think.

I had a similar issue and it turned out to be the crank sensor which would lose its voltage as it got hot from the engine...voltage would drop from 5 volts to 3ish on the scope when it got hot. Easy to replace (relatively for these cars) and might be the fix. Good luck.

pjmcgnns, yes, crank sensor is common solution to starting/running problems, but the `80 does not use one.

While I was thinking the problem is electrical, the immediate drop in fuel pressure that I observed this AM leads me to think I should be looking at the fuel system. i.e. can an injector get stuck open? Is there a check valve in the fuel system that fails? is the drop in pressure indicative of a failing fuel pump?

Hi Joe,
You might want to check the fuel pressure accumulator in the front of the Right Rear wheel well. Sometimes they leak, or not hold the pressure after the engine is off. This is for a CIS system. I think it is meant to keep the forward part of the fuel system pressurized for a while after engine is off to help prevent vapor lock, allowing a hot engine restart.

Al,

Nice to see the engine back in the car.

The 80 was the start of the electronic fuel injection, not CIS. Did they still use CIS in the Euro for 80?

My only comment is to consider removing that gauge, lest you experience something similar.

https://rennlist.com/forums/members/...ngine-fire.jpg

Thanks for the heads up. I have read all the threads on fuel pressure gauges and the pros and cons. At this point the car can not be driven so the goal of the gauge is to help diagnose the problem.

get a can of deoxit spray and drop down the CE panel,
disconnect the battery first,
than go spray the panel spray the fuses/ relays as well.

Clean the grounds on the right hand cam tower, spray them
Clean the battery terminals and inspect the ground cable for internal corrosion,
and replace it if necessary

MrMerlin I ordered a can of deoxit the other day after reading the post about it here on Rennlist. That was my next step prior to having seen the fuel pressure drop to zero when I turned off the engine.

From having read a troubleshooting summary somewhere (workshop manuel?), I was under the impression that the fuel system should hold pressure. Seeing it go to zero within seconds of stopping cranking leads me to believe that there is something mechanical going wrong in the fuel delivery system, i.e. pump, injectors, ?

Leaking fuel injector(s)? Try running a can of techron through system. A bad accumulator will give delayed restart, but not random die.
Good luck,
Dave