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Installing New Low Pressure Fuel Pump 1986 F250 IDI Diesel

Discussion in '6.9L IH & 7.3L IDI Diesels' started by logger1411, Sep 13, 2019 at 6:59 PM.

  1. logger1411

    logger1411 Registered User

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    Argument With Friend...…1986 F250 IDI Diesel I'm installing low pressure pump on inside fenderwell. He said to go from tanks, bypass mechanical pump and go directly to low pressure pump. I understand not to install low pressure pump between tanks and mechanical pump because of danger of rupturing diaphragm in mechanical pump. I say to go from tanks directly to mechanical pump and install low pressure pump on radiator side of mechanical pump. This is actually how it is set up stock, only with new low pressure pump in engine compartment instead down near starter. Am I correct?....logger 1411
     
  2. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    I'm not sure that I completely follow. There's only two fuel pumps on an IDI engine with thee stock set up. They are both mechanical pumps. The fuel flows from the tanks, through the tanks selector valve, through the water separator (on 83-86 unless it's been bypassed), to the lift pump (this is low pressure), to the fuel filter, then into the injector pump (this is high pressure). Are you talking about installing an electric pump? In that case, you have three choices. Either completely bypass the lift pump, install it in parallel with the lift pump using one way valves to keep the fuel from flowing backwards through the other pump, or install the electric pump after the lift pump, before the fuel filter. Any way that you do it, you want the fuel to flow through the filter directly into the injector pump. This is just in case your low pressure pimp has something come apart inside it. You don't want some small pieces going into the injector pump.
     
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  3. Danielle

    Danielle I'm kind of not allowed any more trucks! Supporting Member

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    I recently followed the write up in the tech articles and bypassed my lift pump entirely. Mine is located passenger side.

    I'm never going back! Woohoo!
     
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