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fuel pump problems need help

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by fright89, Mar 8, 2003.

  1. fright89

    fright89 1/2 ton status

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    I have been working on getting power back to my fuel pump, it a Mallory externally mounted and it is very loud so I can here when it’s working. I have replaced the relay and checked my harness and grounds and all seems to be ok.

    You guys have mentioned replacing the oil pressure switch or sensor not sure if thy are one in the same. If so is that the one down behind the distributor, looks like a pain in the a to get to.

    It almost seems like I am not getting power to the relay. I tried putting a meter on the plug connections while someone cranked it but did not get anything on any of the connections. I may not have been doing it right.

    What is the best way to see if I am getting power at the relay? And if not what next?


    Any help appreciated thanks

    Btw 89 with tbi
     
  2. fright89

    fright89 1/2 ton status

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    I have been looking at the manual and correct me if I am wrong the oil pressure switch and sensor are two different components. The switch seems to be down under by the starter and the sensor behind the distributor.

    Tested power again at the relay with the ignition on .no power to the orange wire at the connection.

    The oil pressure switch looks like crap and I guess I will try that next.

    Yes?

    No?
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    So you are running an external fuel pump...are you running it FROM the relay, or do you have it wired up so that it's just switched ignition? If switched ignition, then the relay means nothing. (just mention that because external fuel pumps are typically wired up that way)

    Second thing, are you still trying to draw the fuel through the TBI pump in the tank? Might be wrong, but it would seem to me that if you CAN suck fuel through it, it would at least be slightly restrictive.

    There is an oil pressure sensor for the gauge, and the switch for the fuel pump.
     
  4. fright89

    fright89 1/2 ton status

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    the pump is wired with the relay. the tank was removed and the old, in the tank pump, taken out. it has been this way for about two years with no problem. you can always here it run about two seckonds before you start it and about ten when you shut it off.
     
  5. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    First off just to set the record straight, there is a oil pressure switch for your oil pressure gauge, then there is also another oil pressure switch that allows the fuel pump to continue working should the fuel pump relay fail so long as you have oil pressure. Most people get this confused in the way it works. Second, I am assuming that you have either checked or replaced the fuel pump fuse?
     

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