The fuel pump is kept running by a signal from the ignition, if the engine dies the fuel pump shuts off. That is normal.
Quote:
Originally Posted by whipplem104
This is really odd. You may try with the air cleaner off pushing down on the fuel door and seeing if the idle goes up. This would indicate that the fuel mixture is too lean.
|
I believe that this would indicate the engine was running too rich, an easier way to check would be to unplug a
manifold vacuum line to introduce more air and see if it runs better = too rich. Running worse with extra air indicates too lean. Gasoline engines are sensitive to air leaks unlike your diesel, and to temperature-dependent mixture settings.
It is difficult to diagnose completely from symptoms, often a sensor out-of-spec will cause mixture issues, would need to be diagnosed with an ohmmeter/DMM vs temperature using your FSM. Can be the fuel computer also, they do go bad, I've had two replaced under warranty from driveability issues.
It is unlikely IMO that it is the coil based on your symptoms.
If you can retreive the fuel computer PN, I will look to see if my spare is the same, which would be a 5minute swap, and one way to eliminate that from the mix.
I don't know what years the wire-harness was bad, my '91 was only 5y/o when I sold it, wiring was fine, others here very likely can tell you if yours is a suspect year.
Hot-wired fuses/relays are never a good thing, did the fuse remain good after replacing it? Only the fuse was bypassed, not the relay?
Check also the wiring to the O2 sensor, an unplugged O2 sensor will cause the engine to default to mechanical-injection settings. I don't think it'll affect idle though.
How do the engine grounds look? When it doubt, clean it. Weak grounds can cause you to chase symptoms forever, a couple of millivolt leak to a sensor ground can signal a whole different parameter. Ditto with the fuel computer's ground.