fuel pump always running
May 24th, 2010, 6:46 AM
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fuel pump always running
In my 1998 Blazer the fuel pump is always running unless I remove the relay or unplug the computer Is the computer bad? Even with key off!
Last edited by duanesolson; May 24th, 2010 at 9:24 AM. Reason: Add information
May 24th, 2010, 1:32 PM
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When I disconnect the computer wiring harness the relay releases. Before that I swapped relays. There is a signal coming from the computer that is energizing the relay coil. This has burned out a fuel pump, a relay, and burned out fuses.
I appreciate the advice.
I appreciate the advice.
May 25th, 2010, 4:12 AM
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Thanx
Thanx,
That sounds good... I have been looking thru the schematics and see that, but I cannot find the location of the sensor... But I also see that the sensor directly operates the fuel pump. The only the thing that energizes the relay is the key switch (Or so it seems). The relay is energized at all times. EVEN with the key in the off position. Could it be the ignition switch??? The book is not as clear as I would like it to be. On page 12-26 of HAYNES MANUAL 24071 it shows "IGNITION / FUEL PUMP RELAY CONTROL" in a box with dashed lines around it. Next to that it says "POWERTRAIN CONTROL MODULE (PCM)". Either this is the key switch or a contact in the PCM. There is not a "legend" in the book that clarifies it but it would seem that this is the PCM and should only be energized with the key in the on position.
That sounds good... I have been looking thru the schematics and see that, but I cannot find the location of the sensor... But I also see that the sensor directly operates the fuel pump. The only the thing that energizes the relay is the key switch (Or so it seems). The relay is energized at all times. EVEN with the key in the off position. Could it be the ignition switch??? The book is not as clear as I would like it to be. On page 12-26 of HAYNES MANUAL 24071 it shows "IGNITION / FUEL PUMP RELAY CONTROL" in a box with dashed lines around it. Next to that it says "POWERTRAIN CONTROL MODULE (PCM)". Either this is the key switch or a contact in the PCM. There is not a "legend" in the book that clarifies it but it would seem that this is the PCM and should only be energized with the key in the on position.
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