FUEL PRESSURE QUESTION
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Posting Guru
Joined: Oct 2012
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From: Hat Creek Ca
FUEL PRESSURE QUESTION
Is the static fuel pressure - KOEO - the same if not at max at this point as opposed to when the engine is running or at idle? Just changed my fuel filter and had a leak due to some cockpit failure. Not sure if I corrected the problem but not leaking so far with a short drive and sitting with the key on.
Post Fiend
Joined: Mar 2007
Posts: 26,966
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From: Texas
Electric fuel pump is either on or off, so fuel volume is the same coming from the pump as soon as the key is turned on regardless of the truck running or not.
The FPR controls the pressure and should be close at KOEO and at idle. The running engine might take a little fuel pressure off the reading, but nothing significant. Even WOT shouldn't drop the pressure too much.
In other words, yes, checking for fuel leaks with KOEO is a smart way to do it and should give you about the maximum pressure you're going to see.
The FPR controls the pressure and should be close at KOEO and at idle. The running engine might take a little fuel pressure off the reading, but nothing significant. Even WOT shouldn't drop the pressure too much.
In other words, yes, checking for fuel leaks with KOEO is a smart way to do it and should give you about the maximum pressure you're going to see.
Hotshot
Joined: Jan 2011
Posts: 18,849
Likes: 179
From: Puget Sound
With the spring-type fuel pressure regulator, you will see variances. While one might surmise the fuel pressure would drop a little once started, the opposite can be true. A rise in voltage (once the alternator kicks in) boosts the pump power.
Fleet Mechanic
Joined: Apr 2011
Posts: 1,441
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From: Marseilles IL
Right after I start my truck I can watch my glow plug led and fuel pressure, the second my glow plug led turns off my fuel pressure goes up almost 5 lbs. With my truck at idol is where I see my highest fuel pressure.
Cargo Master
Joined: Jan 2009
Posts: 2,800
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From: OKC, OK
Mine does not do this.
Hotshot
Joined: Jan 2011
Posts: 18,849
Likes: 179
From: Puget Sound
There will be variances - GPs on or not, condition of pump, fuel mods, tuning, etc....
Mine will sometimes bump up a little after starting, and sometimes not.
Mine will sometimes bump up a little after starting, and sometimes not.
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