Fuel Presure changing?
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Junior User
Joined: Dec 2006
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Fuel Presure changing?
Hey all,
I recently installed a fuel presure gauge(0-100psi) on the fuel filter housing and now have noticed some strange readings. When I frist installed the gauge, it was reading about 65PSI and the needle bouncing around + - 5 psi. Yesterday I happened to check it and it was reading around 40psi and bouncing. Today it was reading almost 75 -78 psi. I dont know if having a 1/4 tank of fuel is effecting this or is it a sign of fuel pump failure. I have not done the tank mods yet but planing to. The diesel runs fine and no strange noises or anything. What do you all think it might be tank problems, fuel pump failure, Regulator or what?
Thanks!
99.5 F350 CC LB 4X4
I recently installed a fuel presure gauge(0-100psi) on the fuel filter housing and now have noticed some strange readings. When I frist installed the gauge, it was reading about 65PSI and the needle bouncing around + - 5 psi. Yesterday I happened to check it and it was reading around 40psi and bouncing. Today it was reading almost 75 -78 psi. I dont know if having a 1/4 tank of fuel is effecting this or is it a sign of fuel pump failure. I have not done the tank mods yet but planing to. The diesel runs fine and no strange noises or anything. What do you all think it might be tank problems, fuel pump failure, Regulator or what?
Thanks!
99.5 F350 CC LB 4X4
Post Fiend
Joined: Feb 2006
Posts: 11,892
Likes: 2
From: Middle Tennessee
I think you have air in your pressure source and gauge. It will do that as air will compress as liquids tend not to. If it levels off over time and the truck runs fine, you have air that needs expelling and that ought to explain it. If you pop the hood after 50 miles of driving and see forty psi, then start thinking about the pump if the air is out.
The bouncing is probably your stock regulator spring in the bowl expelling pressure whether it be air or fuel.
The bouncing is probably your stock regulator spring in the bowl expelling pressure whether it be air or fuel.
Thread Starter
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Junior User
Joined: Dec 2006
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The gauge I have is a mechanical one from a military surplus place. I tested it with air comparing with other fuel testing gauges and seamed somewhat accurate. I think I am going to try to bleed any air from it and see if that works. Thanks all!
