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after i replaced the intake gasket and egr valve..started truck, started first try and idled ok for a min or two but then revved real high. i shut off the key but the motor kept running until float chamber ran out of gas. My question is what would cause this? The previous owner told me it might need some carb work. I have never heard of or had an engine just rev its self up real high and not shut off.

I've already replaced spark plugs, wires, points...still doing it..Has the stock hitachi carb on it

Seems like it would have to be a carb issue, but maybe combined with an electrical problem. The revving high would be be something in the carb or the linkage to it. If it idles fine until you step on the gas, then look at the linkage and parts to the throttle cable. It should return all the way to closed when the pedal is released. If not, find what is preventing that. It could be lack of or broken spring, or binding in the throttle cable, or just something loose. If that all moves smoothly and returns to closed ok, then it would probably be something internal in the carb.

The not turning off would likely be electrical. Something is feeding power to the coil or the resistor when the key is turned off. It sounds like the fuel pump cuts off when you turn off the key, but not the ignition. Start looking for any funky wiring, especially around the relays under that cover on the passenger side fender.

I had a similar problem on my 79 actually. The prior owner had done some ugly wiring, and had at one point shorted the big wire to the alternator. The insulation had melted inside the wiring harness and after years of driving it finally shorted to another wire. That wire went to the backup lights switch on the trans of all things. But, that wire could feed power into the ignition system and power the coil. The big wire to the alternator is a straight line to the battery. I would turn off the key and the truck kept running.

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95 Isuzu Trooper Daily Driver
86 Isuzu Trooper reliable backup
77 LUV 2wd stock beltway blaster (resting)
79 4x4 LUV project: 2.6L, 5spd, 31s (eventually)

MEPR: Man, my 4x4 makes all other LUVs look good

Thanks I'll check the wiring, just printed a wiring diagram off this site..most useful website ever..