truck flooding out... BE CAREFUL...

Posted by Bob on March 20, 2006 at 23:01:00 from (64.21.249.40):

In Reply to: HELP! chevy truck flooding out- bad posted by pperry on March 20, 2006 at 19:27:45:

BE CAREFULL HERE!

Have a proper, BIG fire extinguisher at hand, just in case!

NEVER put your face over the throttle body, 'cause if the engine backfires, it will puke up flaming gasoline!

The reason the fuel pump keeps running for 10 seconds is a combination of cold oil and the oil pressure switch that activates the fuel pump. After the engine has been cranked a bit, oil pressure activates the oil pressure switch, and it keeps the fuel pump running for a bit after you stop cranking, until the pressure switch "drops out".

If you can find the oil pressure switch that controls the fuel pump, and pull the connector off of it, then the fuel pump will only run for 3 seconds when the key is first turned on, and while cranking, under control of the ECM.

(The oil pressure switch is a back-up to the ECM and fuel pump relay turning on the fuel pump.)

Now, for the cause of the flooding.

There are 2 possible causes...

1.)Fuel leak due to mechanical reasons... a stuck injector, or bad "O" ring or fuel pressure regulator in the throttle body.

2.) Constant spraying of the injector due to it's being energized electrically by a short in the wiring or a bad engine control computer. When the ignition switch is "ON", power is fed to one side of the injector. The ECM grounds the other side each time the injector is to inject gasoline. If the wire on the computer side of the injector is shorted to ground anywhere between the fuel injector and the ECM, the injector will spray fuel continuously, as long as the ignition switch is "ON", and there is fuel pressure. Also, a shorted "quad driver" inside the ECM can cause this.

To check to see if the problem is electrical, (safely, with the key "OFF"), pull the wire connector off of the fuel injector.

Then, try cranking it again. LISTEN TO ME CAREFULLY HERE... Even while the fuel pump IS running, NO FUEL should leak into the throttle body, or spray from the injector with the electrical connector unplugged.

THE ONLY TIME any fuel should spray from the injector (with the connector re-attached) is while the engine is cranking or running, and the computer is pulsing the injector.

Once again, if the engine is NOT turning over, ABSOLUTELY NO FUEL should spray into the throttle body, EVEN IF THE FUEL PUMP IS RUNNING!

Replies:

• Re: truck flooding out... BE CAREFUL... pperry 03:30:41 03/22/06 (0)

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