Car will not run?

Matt94

Registered
I was driving in the 94 and it suddenly started to feel like it was out of gas. Soon after it stalled. It would only start for a second if the pedal was to the floor. I let it sit and it would start back up, run fine without hitting the gas for only 30 sec then it would run bad and stall. Im getting 38 psi of fuel pressure and have 13 gallons of fuel in the car. Any thing?
 
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Maybe a bad Throttle Position Sensor or Idle Air Control Valve. Also a possible Mass Air Flow Sensor, but I don't think the MAF typically cause stalling, just rough running.

Those would be my first guess. I'm assuming the Mark VIII had dual distributorless ignition, so maybe one of those coils is going out, or you have some bad plug wires/plugs. But I doubt it.

Those are my initial guesses. Good luck!
 
I unpluged the mass air and it still didnt run. It has 140,000 on the body, about 70,000 on the motor. no check engine light. if it sits for a while it will run at idle for a min but if any throttle is given it stalls and will only start at wot for only a sec.
 
If you have a DMM or voltmeter check the single pin on the diagnostic port. It is the fuel pump supply voltage. You should see about 5 volts on this pin with the ignition on and also in the start position or it wont start. Listen for the fuel pump to turn on for about a second after you turn the key to the on position. Once it starts the voltage will drop to 3.something volts as the demand drops and or stabilizes. If you have a code reader you might note that it wont even begin the KOEO test till after your thirty second or so wait. Sounds like a phlakey VCRM. There is a relay inside that can really cause plenty of problems much like a bad alternator or something. Tapping on it with the but end of a screwdriver can sometimes be a good diagnostic tool if you dont have a spare VCRM laying around. This is an easy check so I thought id mention it. You may also be losing spark. All this stuff works on a ground interrupt system so make sure your battery ground connections are good and clean.
 
If you have a DMM or voltmeter check the single pin on the diagnostic port. It is the fuel pump supply voltage. You should see about 5 volts on this pin with the ignition on and also in the start position or it wont start. Listen for the fuel pump to turn on for about a second after you turn the key to the on position. Once it starts the voltage will drop to 3.something volts as the demand drops and or stabilizes. If you have a code reader you might note that it wont even begin the KOEO test till after your thirty second or so wait. Sounds like a phlakey VCRM. There is a relay inside that can really cause plenty of problems much like a bad alternator or something. Tapping on it with the but end of a screwdriver can sometimes be a good diagnostic tool if you dont have a spare VCRM laying around. This is an easy check so I thought id mention it. You may also be losing spark. All this stuff works on a ground interrupt system so make sure your battery ground connections are good and clean.

Ok, good info, I hot wired the pump to see if it would help, but nothing, I put a new fuel pump in and it did not fix it, it still will run for a sec when cold then it will not start again. Maybe it could be a crank sensor or something? But I will go a head and try those methods. And also when I hot wired the pump I could hear a relay click when ever I put power to the pump.
 
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If you have a DMM or voltmeter check the single pin on the diagnostic port. It is the fuel pump supply voltage. You should see about 5 volts on this pin with the ignition on and also in the start position or it wont start. Listen for the fuel pump to turn on for about a second after you turn the key to the on position. Once it starts the voltage will drop to 3.something volts as the demand drops and or stabilizes. If you have a code reader you might note that it wont even begin the KOEO test till after your thirty second or so wait. Sounds like a phlakey VCRM. There is a relay inside that can really cause plenty of problems much like a bad alternator or something. Tapping on it with the but end of a screwdriver can sometimes be a good diagnostic tool if you dont have a spare VCRM laying around. This is an easy check so I thought id mention it. You may also be losing spark. All this stuff works on a ground interrupt system so make sure your battery ground connections are good and clean.


I tapped on the VCRM and nothing, I saw around 5 volts at the diagnostic port. I can get a VCRM for $25 should I buy it and swap it out? I really need to get this car running and I have already put a ton of money in it, I know there has to be something stupid thats wrong with the car.
 
Usually the best diagnosis for the 'black box' modules is swapping them out. Using a known good one is best but $25 is a steal if it works.
 
I agree! I take it for granted sometimes because I have a parts car on my property. Auction site may do you well.
 
This problem sounds way too familiar! I recently ( six months ago ) added yet another mark to my already overwhelming collection. I was reluctant to purchase the car at first. A 93, it still had the drive out tag from the previous owner in the back window. The tag was over three years old. In addition to being parked in the backlot at a mechanics shop where it had been surrendered for payment. After talking with the mechanic, he had no doubt been fed up with the whole situation. He gave me a brief description of the entire event as well as his attempts to get the car running. I dont mean to bore you with trivia, but I also was totally at a loss after many hours of trial and error. I took each part one at a time off of a running car swapping them to the 93 and back to the donor car with no luck. At the very least I learned a lot about these cars in that six weeks. After starting with the fuel pump next came the EEC, ECM, PCM, crank position sensor, camshaft position sensor, idle air control valve, throttle position sensor, mass air, fuel filter, fuel injectors, plugs, plug wires. After all that, I took the exhaust loose at the manifold on the passenger side, and after the converter on the driver side. Before I went any further I got up turned the key and I finally got to here her come back to life. :eek: So my new discovery was a stopped up catalytic converter! The one in the middle the two head pipes dump into. Man I hope this helps! Good luck and sorry to be so long winded. This whole thing became very personal. But for another cherry pearl white 94 $700 was a steal!
 
Yeah! That sounds familiar. I worked in a Jeep/Chrysler dealer for 6 years. The common problem with the jeeps was if someone backed into a snow pile and water collected in part of the tail pipe and froze.

I've seen several cat converters get plugged up and melted inside, especially if the car had a dead skip for a long time and did'nt repair it right away. When the cat cools down, the honeycomb type material in the cat will contsrict slightly allowing a small amount of exhaust to flow through when cold.

If you don't want to remove the exhaust entirely, in the past I have removed the O2 sensors from before the cat. This will allow just enough exhaust gasses to escape and hopefully it will stay running longer than before. If it does stay running check the tail pipe and see if there is anything at all coming out of it.

Good luck.
 
Well i replaced the vcrm and it didnt do anything. Im going to try and do the exaust thing, it sounds crazy but if it works that would be insane.
Thanks Matt
 
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