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Son_of_Norway's avatar
Son_of_Norway
Explorer
Sep 17, 2020

Fuel pressure gauge went backwards

Hello, the coach is stalling and dying on acceleration and I'm trying to make a definite diagnosis. I installed a fuel pressure gauge along the frame rail just downstream of the fuel tank so I can tell if the in-tank fuel pump is working. When I started the coach the needle went backwards and pegged at the opposite side. I'm thinking this means the in-tank fuel pump is not working and gas is being drawn forward by the mechanical pump. Is this correct? I'd like to be sure before I start trying to drop the tank. Thanks to all for your help.
Class A
  • fulltimin's avatar
    fulltimin
    Nomad
    Sep 17, 2020
    If this is the rig in your sig, it may or may not have a fuel pump in the tank. A lot of rigs built in that time frame had none in the tank.

    However, it may depend on whether or not this has a carb or is fuel injected.

    If it has a carb, best place to put the gauge is between the engine mounted fuel pump and the carb.

    If it's fuel injection, then usually there was a tank mounted pump, with no pump mounted on the engine.
  • schlep1967's avatar
    schlep1967
    Nomad
    Sep 17, 2020
    Is it possible you attached your pressure gauge to a return line to the tank? Look for another line.
  • 1995brave's avatar
    1995brave
    Nomad
    Sep 17, 2020
    I see you have a Chevy chassis with 454. Is it throttle body or carb? On the passenger side just in front of the rear axle should be a fuel filter. You can always connect your pressure gauge before or after the filter to check fuel pump pressure.

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