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73-87 Chevy _ GMC Trucks => Electrical => Topic started by: Shawn0331 on May 14, 2012, 05:00:11 pm

Title: Fuel Pump On Engine Off
Post by: Shawn0331 on May 14, 2012, 05:00:11 pm
87 5.7L TBI.

After I shut the engine off, a few minutes later the fuel pump kicks in for a while. Normal?
Title: Re: Fuel Pump On Engine Off
Post by: VileZambonie on May 14, 2012, 05:07:15 pm
On heavy duty models, a fuel module will override the ECM two second timer and the fuel pump will run for twenty seconds and then shut OFF if the vehicle is not started. This circuit corrects a hot restart (vapor lock) during a high ambient temperature condition. Refer to COMPONENT LOCATIONS/UNDERHOOD BLOCK DIAGRAM for under hood general location.
Title: Re: Fuel Pump On Engine Off
Post by: Shawn0331 on August 13, 2012, 02:33:49 pm
Well, I know it's been quite a while since I posted this, but after replacing my oil pressure switch (which was never there...PO must have removed it), I looked at the fuel pump relay and saw this.

AutoZone has a cheap replacement. Hoping this solves the problem. I believe the fuel pump running has been what is draining my battery dead when I don't drive it for long periods of time (3-4 days or longer).
Title: Re: Fuel Pump On Engine Off
Post by: j20m715 on November 27, 2012, 11:54:19 am
On heavy duty models, a fuel module will override the ECM two second timer and the fuel pump will run for twenty seconds and then shut OFF if the vehicle is not started. This circuit corrects a hot restart (vapor lock) during a high ambient temperature condition. Refer to COMPONENT LOCATIONS/UNDERHOOD BLOCK DIAGRAM for under hood general location.


 If this module is BAD what conditions will it cause ?

 What if module is removed ?