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Speedy Squirrel Speedy Squirrel is offline
Rocket Scientist
Join Date: Jun 2008
Location: Detroit
Posts: 948
Here is some background so that you will understand what follows. You don't want the fuel pumps on when no air is flowing through the engine, and you don't want the fuel pumps on when the engine has stopped turning. Both of these are bad from a safety standpoint, so remove from your mind that current flows to the fuel pump relays from the ignition key.

There are two "relays" that can cause your problem. One is the Air flow sensor charging pressure relay. It takes inputs from a switch that is mounted on the airmeter, and a speed signal from the speed relay. It removes the ground from the fuel pump relays if there is no engine speed, or the airflow switch is closed.

So, you have three possibilities, airflow switch (easy to jumper across to test), speed relay (mounted under seat, no fun to diagnose), or Air flow sensor charging pressure relay (easy to get at in the engine compartment).

Fortunately, our hosts here carry these parts (last I looked).

Or you could get REALLY mad and replace all this stuff with EFI, which is what I did!
Old 02-21-2009, 08:27 PM
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