I just recharged my battery after the long winter sleep of 5 months and got my '91 C2 on the road. It is missfiring at times. At other times it runs great. When it starts to miss, it gets progressively worse. When it does missfire, the tach and speedo drop a bit and the check engine light flickers during the moment of missfire. I am not sure if the missfire is caused by a fuel or temporary electrical problem. It almost seems like a fouled plug. Would that cause the apparent electric drop at the time of the missfire? Could it be old fuel? Sorry Adrian. I could not find the problem stated in your book.

 

Mine is having missing issues right now too. I have made an educated guess that it is a bad coil and placed an order for that plus caps and rotors. You may want to check those areas.

 

BLK 964 was having misfire problems. All ignition parts were new, and checked out fine. Root cause was the O2 sensor was causing rich running, and the plugs were fouling. Get your fault codes read. The diagnostic system is pretty good at recognizing a bad O2 sensor.

Parts are expensive, and getting to the failed component before replacing a lot of good parts saves big money.

 

Bad gas is always the first thing to assume, especially after a long storage. I've even filled up with bad gas that caused pinging (pinking, knocking...) whenever I pushed hard on the gas... either drain your gas and refill, or drive your tank empty then refill with some new gas and maybe some Techron to run through the system. That's the cheapest and easiest way to start

 

I've also got a bad gas problem but it really only affects my upholstery.

 

 

buh dum ching (hitting the cymbals)
Brian

 

Wife put regular gas in her 91 C2 Cab...about 3/4 of a tank. Do you think that will cause a problem?

 

Condensation from sitting so long may have allowed a little water to build up in the system. I would also be inclined to check the distributor belt....it would be coincidental but stranger things have happened.

 

To Mathew with the '91 C2 Cab, we have identical cars; even down to the engine missfire. Follow-up question on the problem. If the missfire was from bad gas, would the drop in the tach and speedo happen? In other words, would it cause the electrics to "die" for that millisesond? I think not. That's why I suspect an electrical problem. But I have been wrong before.