Weird Misfire

[Datbonneville1]

Hey all, just took a trip from southwest CT over to charlestown RI. Developed a misfire about halfway on the trip there. It effects acceleration, and you can definitely tell its missing if you rev the engine from under the hood. If i try to accelerate and downshift from about 3k to 4.5k, itll reach about 4k and it just seems to lose power. Or ill try to downshift from 3k and itll just stay at 3k, and i have to almost floor it get it to bust loose and go up to 4.5k. you can really feel it too if you accelerate lightly from a stop. Any ideas anyone?

[Datbonneville1]

Also, when the car starts up cold, it has an erratic idle. Fluctuates by a couple hundred rpm until car somewhat warms up, then it evens out.

[KM AXer]

My '93 did something similar, then it cleared up for a couple of weeks. Then it started back in earnest, when my sons had the car in Canada, many miles from home (of course).

Turned out to be a defective coil. The first go-around I think the spark must have been weak/intermittent. The second was an outright failure. Was easy to find, I just pulled a couple of plug wires, one at a time. The difference between a spark looking anywhere for a ground and none at all was hard to miss.

[nos4blood70]

As mentioned above, check over your entire ignition system.

[Datbonneville1]

SOLVED. Car has a weak fuel pump, put gauge on it and its only giving out 15lbs of fuel when its running. Should be around 40 or 45lbs. Plugged fuel return hose to see if pressure shot up and it stayed right at 15lbs. Its not even pumping enough to get past regulator and piss out the return line.