stall and start
bigbluecappy
08-05-2006, 11:22 PM
I have a 94 caprice with a 4.3 liter v8(L99),had to buy a fuel pump when i bought it.since then i've bought three distributers,a spark control and ignition module,optima red top battery,fuel filter,plug,wires,water pump and air filter over the 1 year iv'e had it.. now it stalls cranks but wont start unless it sits for hours then starts wright up with no problem, it could run for days or 5 min untill it does the same thing.it did the same thing before I replaced the distributer don't tell me I need another one what could this problem be.could it be my computer cause sometime my digital dash flickers and sometime on occasion reads error..please help me.. all leather all power great body nothing major just two small dent full ragtop beutiful car I don't want to give it up.
HLandin
08-06-2006, 09:59 AM
Sounds like a couple of different problems.
Your dash flickering seems to be a very common problem encountered on the 94-96 Caprice. From what I've read, it is caused by high resistance in the contacts on the back of the dash not making good contact. You'll probably have to clean/replace them to make good contact.
As far as cranking but failing to start, it could be several things and the rest of the forum could probably help you better; however, it has been posted before that (atleast in the TBI Caprice) if the oil pressure is not high enough after attempting to start, the engine will not start. Looking at a schematic, the pump will not continue to run without either a closed pressure switch or power from the ECM (the computer will not continue to power the pump unless it receives a signal from the distributer after trying to start). This is to prevent the pump from running if the engine should fail to start due to other conditions.
One more thing, does you pump run briefly when the ignition goes from off to run (before start). It should to pressurize the lines. If it doesn't, it could be another problem.
Your dash flickering seems to be a very common problem encountered on the 94-96 Caprice. From what I've read, it is caused by high resistance in the contacts on the back of the dash not making good contact. You'll probably have to clean/replace them to make good contact.
As far as cranking but failing to start, it could be several things and the rest of the forum could probably help you better; however, it has been posted before that (atleast in the TBI Caprice) if the oil pressure is not high enough after attempting to start, the engine will not start. Looking at a schematic, the pump will not continue to run without either a closed pressure switch or power from the ECM (the computer will not continue to power the pump unless it receives a signal from the distributer after trying to start). This is to prevent the pump from running if the engine should fail to start due to other conditions.
One more thing, does you pump run briefly when the ignition goes from off to run (before start). It should to pressurize the lines. If it doesn't, it could be another problem.
Blue Bowtie
08-06-2006, 06:40 PM
A couple things can happen "after it sits for hours."
First, an overheated ignition module (mounted to the front of the LH head) can have a chance to cool and begin switching coil primary current again.
Second, any accumulated moisture in the OptiSpark distributor optical array section can condense, collect at the bottom of the distributor, and and allow the photo source and receiver to "see" through the slotted timing discs until the moisture is again vaporized and interferes with the optical array.
Third, any excess fuel which may have leaked from a faulty fuel pressure regulator diaphragm and collected in the intake plenum will have had a chance to evaporate instead of flooding the engine on hot restart.
Intermittent electrical connections (including ground connections) can cause any manner of faults and problems.
Further input from you will help a lot in the diagnosis.
As for the instrument cluster, HLandin is absolutely correct (as usual) that the connectors are a good place to check first.
http://72.19.213.157/files/B-BodyI-PConnectors.jpg
First, an overheated ignition module (mounted to the front of the LH head) can have a chance to cool and begin switching coil primary current again.
Second, any accumulated moisture in the OptiSpark distributor optical array section can condense, collect at the bottom of the distributor, and and allow the photo source and receiver to "see" through the slotted timing discs until the moisture is again vaporized and interferes with the optical array.
Third, any excess fuel which may have leaked from a faulty fuel pressure regulator diaphragm and collected in the intake plenum will have had a chance to evaporate instead of flooding the engine on hot restart.
Intermittent electrical connections (including ground connections) can cause any manner of faults and problems.
Further input from you will help a lot in the diagnosis.
As for the instrument cluster, HLandin is absolutely correct (as usual) that the connectors are a good place to check first.
http://72.19.213.157/files/B-BodyI-PConnectors.jpg
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