4100 quit then started again later

[TJ Hopland]

Friend last night called and said his 84 CDV just quit.   He has been daily driving it and its been fine.  He drove it to work yesterday then was home for a few hours.  Started it up to go out for the night all was normal.  Waited for the wife to come out and it just quit and would not re start.  He did have a chance to see that there was no fuel coming from the injectors.  Took another car to his destination but when he got home 5 hours later it started and ran fine.   

That was obviously not the distributor drive gear stripping because that would not recover.   Also does not quite seem to fit fuel pump.  My experience on the TBI's is unless the pump is 100% dead they usually dribble fuel and sputter a little and 100% dead pumps usually wont recover themselves. 

Ideas?   

[76eldo]

Could be computer related, but I would suspect fried wires down by the starter and oil pressure sender down on the oil filter adapter.  There is a 3 wire connector down there that basically disintegrates due to oil and grease and heat.  If the wires are intermittently making contact, that would give the symptoms described.

No oil pressure signal on one of these wires will shut off the fuel pump.

It's an educated guess, but without seeing the car in person, it's something.

brian

[Dave Shepherd]

Could be computer related, but I would suspect fried wires down by the starter and oil pressure sender down on the oil filter adapter.  There is a 3 wire connector down there that basically disintegrates due to oil and grease and heat.  If the wires are intermittently making contact, that would give the symptoms described.

No oil pressure signal on one of these wires will shut off the fuel pump.

It's an educated guess, but without seeing the car in person, it's something.

brian

Good info and somewhat common, also the ecu was another known issue for this, as well as the ign module.

[TJ Hopland]

I cant seem to find my 83 shop manual at the moment, odd since its like 3x the size of the rest.    I knew that GM often used the oil switch to keep the fuel pump running but I assume that the fuel pump runs when key comes on and during cranking also through other relay control methods?   Or will a failure in that switch or harness cause it not to run at those times either?

Ignition module failing then recovering?   

[Dave Shepherd]

The ign module has an analogue input into ecu that results in the injectors pulsing, when it won't start a " noid" lite can be plugged into one of the injector connectors, then you can see if the ecu is pulsing the injectors ,if not, either the pcm, harnesses or ign module are usually the problem, the wire harness at the oil filter/oil pressure switch can  be an issue and kill the fp.

[76eldo]

You can see the connector if you crawl under the car, or better yet, get it on a lift.

If the wires are not making a clean contact the fuel pump will not continue to work.  It's a safety feature to kill the fule flow in case of an accident or stalled engine.  No oil pressure (or reading), no fuel flow.

I have experienced this and fixed it before on other HT4100, but the wires down by the starter on any year Cadillac can get brittle because they cook from all of the heat down there, and the oil.

Brian