RE: Computer Codes & Fuel Pump

Date: Tue Feb 27 1996 - 09:02:32 EST

From: on Mon, Feb 26, 1996 7:35 PM

>I also wouldn't worry too much about damage to the fuel pump. I know that on
>my 89, the pump will only run for a max of 1 sec if the computer doesn't
>detect a rise in fuel pressure. I know this because I attempted to pump out
>some bad fuel using the on board fuel pump. I disconnected the line at the
>filter, but fuel would appear for only 1 sec each time the key was turned to
>either ON or START. Needless to say, I ran the bad fuel through the engine
>anyway. I'm not sure if Fords & GMs have this feature.

FYI, it is not a rise in fuel pressure that shuts down the fuel pump. If the
computer does not detect a signal from the distributor indicating the engine is
cranking it shuts down the fuel pump. This is part of the federal safety
regulations that require electric fuel pumps to shut off if the engine stops
running or the vehicle has rolled over. The intent is to prevent the fuel pump
from pumping gas all over the ground in the event of a fuel line rupture during
an accident. All vehicles with electric fuel pumps have some system to
accomplish this. There is a relay in CC products called the Automatic Shut Down
(ASD) relay that cuts off power to the fuel pump, fuel injectors and ignition if
the computer does not detect the engine running or if the vehicle is not on it's
wheels. My Ford has a circuit breaker in the trunk that needs to be manually
rest under these conditions.

Dave Clement

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