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Old 01-18-2012, 04:58 AM   #171 (permalink)
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An electric fuel pump not running is most likely the pump gone bad, but it can also be other things.

The way most are set up, they run for a bit when the key is turned to Run, then shut off. That's to pressurize the fuel system. When the key is turned to Start, the pump is supposed to turn on again.

When the key is let back to Run, one or more engine sensors are used to signal that the fuel pump shall continue to run. Some systems use the oil pressure sensor. Others use the crankshaft or camshaft sensor.

Something quite a bit less expensive and easier to change than the fuel pump, and just as likely to go bad is the fuel pump relay. The relay is most often under the hood somewhere near the left or right side, typically in or next to the under-hood fuse and circuit breaker box.

What's rough on fuel pumps is running around with the tank nearly empty. The pump motor uses the gasoline for cooling. Some vehicles (mostly GM for American makes) have a porous foam sleeve around the motor to wick up fuel* when the tank is nearly empty. Some others (like a 1998 Chrysler Sebring convertible) have nothing like that, and replacement motors aren't available, just the whole bleeping $200 pump assembly.

*Which didn't stop the pump in my 1986 Cimarron from quitting and leaving me stuck in the middle lane on a five lane road.

What's really frigging annoying is in-tank electric fuel pumps just love to die right after filling the tank. Can't go *poof* when there's just fumes in there, too convenient.

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