Question about 1991 Chevrolet Caprice
THE MOTOR CAME OUT A CHEVY TRUCK 1500 350 V8
First understand how the fuel injector circuit works that causes them to spray fuel out, then you could probably find the problem. It's really simple, the key thing is that the hot wire to the injector (there are only two, a power wire and a ground wire) is always hot anytime the ignition key is in on, or run, or start. It is a fused circuit that is powered on when the key is on. The fuse is either in the distribution box under the hood or in the instrument panel fuse block.
The ground wire from the injector goes into the computer where it can be internally grounded inside the pcm for a split second. This is what causes the "pulse" of the injector, a needle is raised electromagnetically, and fuel under pressure is sprayed out. The computer can vary the pulse width, by duration of ground time, and really fine tune the gas metering.
Check for power at the injector connector with key on. If nothing, check the injectors fuse, and trace it back to the ignition switch. If there is power on the hot wire, one way to further test the circuit is to go buy a cheap "noid light," a tester at any parts store-different sizes, but easy to find a standard for gm vehicles. A noid light checks power and ground wires at the same time. Now that you understand "pulse", a noid will blink as if it were being pulsed-well it is, just that. Hook it up to an injector connector, and the engine has to be cranking over-that is when the computer is grounding the circuit repeatedly-when the engine is running and when it is cranking by the starter. If the noid light blinks, the circuit is working correctly. If the light doesn't turn on at all, first verify that the power wire has power with key on. If it does, problem may be in the ground side of the circuit, or in the pcm itself.
Posted on Mar 30, 2014
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Posted on Jan 02, 2017
You block it off before the valve on the metal pipe that runs to the EGR valve. The problem is that when you go to get it smogged you have to replace the EGR or it will not pass smog
Posted on Feb 13, 2009
it may not be a vacumn leak from a line,check the throttle shaft for movement,for example,i had a 89 1 ton 350 and my throttle shaft was moving around a lot and in order to keep it from idling high,i had to kick the throttle pedal.But also check the idle air control valve,which is the round sensor on the side of the throttle body.
Posted on Sep 11, 2009
I had a similar problem on an 84 Lincoln Mark VII. Found out it was a ground wire that had broken running from the wiring harness to the fender well. The wire was broken inside the shielding and not visible. You might consider going through and checking all of the plug connections for corrosion as well. This may not solve the problem but certainly easy to check.
Posted on Dec 27, 2009
Sounds like a o2 sensor, if you don't have a check engine light on, you soon will. The PCM can be scanned to find out which one is faulty.
Posted on Feb 21, 2011
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