Duck

Trying to help a new friend in town that has 1990 C2 Cab. It has been at a mechanic in town for many months. The issue is that the car will randomly shut off. Unfortunately I have not actually witnessed it, but the last time it happened I was told that it was just idling. I am trying to help track down the possible root cause. Things that I believe have been done:

DME Relay replaced
DME has been sent off and checked
Looks like fairly new plug wires
TSB for MAF plug
It is getting fuel
No fault codes
Idle switch is working
Supposedly the grounds have been checked(but not sure all of them)

One concern that I saw was new plug installed for crank sensor. It seemed to be connected okay, but some of the shielding is missing.

I am trying to get a checklist of items to cover. Any ideas are greatly appreciated.

Thank you.

Andy Roe

I wonder if a bad connection to the battery could cause this? Have you checked the condition of the cables?

Duck

Thank you. I will definitely put that on the list of checks.

DobermanDad

Turn of as in now power or stall?

Duck

I am not positive since I have not seen it happen. I believe it just stalls. The mechanic that has it thinks it is ignition related and just not getting spark. Will ask the owner what happens after the stall.

Thanks.

Duck

Power is still on - just stalls.

g60pops

02 sensor, has it got wet recently? Driving through rain water etc?

Andy Roe

What about dirt in the fuel tank or a blocked fuel filter? Once the engine stops, whatever causes the blockage moves when the fuel pump switches off and then you can start the car OK. Something like this would be very random too.

Duck

Thanks for the ideas. I am putting a checklist together. Told the guy to start driving the car again since it has just been sitting. If it happens again, note all the details (how warm the engine was, idling or on gas, etc.).

Thanks again. The guy has lost confidence in the car so want to help him gain it back.

boxsey911

Has the mechanic checked for fault codes using a hammer as this might give a clue?

Have they tried doing an idle adaption with a hammer to solve the problem?

The stalling problem on mine was caused by a faulty hall sensor (as diagnosed by the hammer). The usual fix for this is to replace the twin distributor unit (in my case we rebuilt the distributor with a new hall sensor). I could temporarily solve the stalling problem by unplugging the hall sensor which puts the ignition timing into a default mode that doesn't use the signal.

DobermanDad

Is the ISV clean?

Duck

Well it is worse now. The car will not even start. Went by and changed out AFM and ISV. Tried to start it again and no luck. Tried connecting my PDT-999 and it would not read the motronic. Last week I was able to connect and even run adaptation and now nothing. I checked voltage at pin 18 and 37 and had about 11.7v (battery drained a little from trying to start it).

Tried to connect my PDT-999 to my motronic but it would not connect but i am guessing it is because so much is disconnected from the engine being out.

The guy is very frustrated with the car. I am hopeful to get it back running again. It is probably something like a bad ground, but cannot seem to find it.