expected fuel pressure results?
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Post Fiend
Joined: Mar 2002
Posts: 19,402
Likes: 38
From: Bonita Springs FL
expected fuel pressure results?
I have a '90 F-150 6-300 and I tested the fuel pressure the other day and got some odd results.
With KOEO (Key on, engine off, right? <blink> New user!!! </blink>), there's no pressure in the system. None at all. Engine was running five minutes ago.
So I switch it on, and the needle swings up to 52psi or so. Perfect. When I flip it to the rear tank, it drops to 20. That's why it won't run on the rear tank, obviously.
When I switch the engine off, the needle immediately drops back to zero. I thought pressure was supposed to stay in the system?
Two questions - is this normal behavior? How do I fix the weak pressure problem? (I'm assuming replace the rear pump, but I haven't been doing this very long.)
Thanks!
Andy
With KOEO (Key on, engine off, right? <blink> New user!!! </blink>), there's no pressure in the system. None at all. Engine was running five minutes ago.
So I switch it on, and the needle swings up to 52psi or so. Perfect. When I flip it to the rear tank, it drops to 20. That's why it won't run on the rear tank, obviously.
When I switch the engine off, the needle immediately drops back to zero. I thought pressure was supposed to stay in the system?
Two questions - is this normal behavior? How do I fix the weak pressure problem? (I'm assuming replace the rear pump, but I haven't been doing this very long.)
Thanks!
Andy
Senior User
Joined: Feb 2002
Posts: 402
Likes: 0
expected fuel pressure results?
Check with a Ford dealer,there is a unadvertised recall if you will on the check valves in the dual tank system.I know of a couple of people who have had problems fixed by ford.Does the level in the other tank increase?I know of one instance where one tank would pump to the other,could explain your low pressure.
Billy
Billy
