1997 Chevy Truck random cylinder missfire (fixed updated

TUBEDVEGA

MEMBER
1997 CHEVROLET TRUCK
V8
4WD
AUTOMATIC
30,400 MILES

Hi new here, HELP! My sons truck (my old one) has has been running very rough lately. (Random rapid missfire)I have spent over $1,000 on it and its seen one mechanic also. I started out with complete ignition system, wires, plugs, cap and rotor with no luck. Took it to a mechanic, he replaced CSFI spider unit and truck ran fine for 2 weeks then started acting same again. Took it back to mechanic and he said fuel pump pressure was low and check valve imediatly bleeding off, I replaced pump, truck ran good for 1 minute then started missing again bad. I replaced fuel filter then truck would barley start and now wont hardly run. Falls on face when giving gas and dies. I only replaced pump not whole unit. Could it be bad ground from pump and does this truck have pump regulator and wheres it located? The cat converters are hollow (cleaned out also)

5 Replies

RASMATAZ

MECHANIC
75,992 POSTS

Random cylinder misfire-is caused by vacuum leaks and bad fuel.

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Saturday, July 31st, 2010 AT 8:44 AM

TUBEDVEGA

MEMBER
5 POSTS

Thanks for a very quick response. Ill check vaccuum and gas. Just thought it kinda weird changing the filter made it even worse. Also why did it run fine for 2 weeks after CSFI was changed out then crap out again? Whats the chances the new unit is failing and are they usually covered under waranty?

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Saturday, July 31st, 2010 AT 9:40 AM

RASMATAZ

MECHANIC
75,992 POSTS

Other causes:

1. Defective spark plug.
2. Inadequate spark/coil, defective spark plug wire.
3. Lack of compression
4. False air leakage.
5. Faulty fuel injectors.
6. Insufficient fuel pressure.
7. Contaminated fuel.
8. EGR valve that is leaking.
9. Oxygen sensors.

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Saturday, July 31st, 2010 AT 9:43 AM

TUBEDVEGA

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5 POSTS

Thanks for the list of suspects, 1, 2, 5, 6, 8 should be taken care of, as its been replaced and checked. 3, 4, and 9 are some thinks ill check!

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Saturday, July 31st, 2010 AT 9:48 AM

TUBEDVEGA

MEMBER
5 POSTS

Well after giving up I took it to a shop. They had fits trying to find the cause. It ended up being corrosion in the wirening harness plug to the distributer module. Runs like a top now. Just thought some might want to know thats having similar problems, something to check. It was getting a voltage loss to the distrib at times.