Low fuel pressure
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Joined: May 2004
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From: Upstate NY
Low fuel pressure
My friends '03 7.3 fuel pressure will not go over 50 psi. Truck has the factory fuel pump with over 250k on it. Also has riffraff fuel rail crossover installed. I put a normal o-ring on the fuel pressure poppet couple weeks ago since original was torn. Brought it up to 60 psi. I ordered and installed a new poppet with new seal and now it is stuck on 50 psi. The new one I bought does not have the small hole in it like the original. I put the original poppet in with the new seal and still same thing. Also changed springs and still stays at 50 psi. Could the fuel pump be going bad?
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Joined: Oct 2008
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My friends '03 7.3 fuel pressure will not go over 50 psi. Truck has the factory fuel pump with over 250k on it. Also has riffraff fuel rail crossover installed. I put a normal o-ring on the fuel pressure poppet couple weeks ago since original was torn. Brought it up to 60 psi. I ordered and installed a new poppet with new seal and now it is stuck on 50 psi. The new one I bought does not have the small hole in it like the original. I put the original poppet in with the new seal and still same thing. Also changed springs and still stays at 50 psi. Could the fuel pump be going bad?
There are several other things that can affect fuel pressure:
(Mostly in order of occurrence)
Bent or miss installed spring
Mixing Chamber Filters Clogged.
Fuel Pump
Defective Regulator
Obstructed / Dirty Fuel Bowl
Aftermarket Fuel Filter
Defective Riser in Fuel Bowl
Hotshot
Joined: Jan 2011
Posts: 18,849
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From: Puget Sound
Air in fuel can cause this too - bad quick-disconnect O-ring seals on the fuel line from the tank to the pump.
Since the problem started with the installation of the FRx and modifying the regulator, that might be a hint that the fuel pump was on the edge, and the added return flow was just a little too much. You really need to open the fuel bowl drain valve into a container and measure the flow as you look for bubble in fuel.
Since the problem started with the installation of the FRx and modifying the regulator, that might be a hint that the fuel pump was on the edge, and the added return flow was just a little too much. You really need to open the fuel bowl drain valve into a container and measure the flow as you look for bubble in fuel.
Thread Starter
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Joined: May 2004
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From: Upstate NY
Pulled tank today and found filters plugged. So did in tank mods. Now pump is super quiet. Only gets about 59 psi at idle, but only drops to about 50 psi when standing on it. So I guess I need to look at the fuel pressure regulator again.
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Posting Guru
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Those are good numbers! I wouldn't mess with it at all unless he's Stage II or better.
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Hotshot
Joined: Jan 2011
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From: Puget Sound
59 PSI is perfect, but dropping to 50 PSI is not - and that has absolutely nothing to do with the regulator. A regulator's job is to limit the max pressure. Altering the regulator will change the 59 PSI number, but that one is perfect. It's that dip to 50 PSI that would be of concern to me - I never drop below 55 PSI on an OEM pump with my Stage IIs lathing tires.
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