fuel pressure drops quickly.
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Tuned
Joined: Sep 2007
Posts: 455
Likes: 6
fuel pressure drops quickly.
my van has been running really rough lately.very hard to start.i finally got a fuel guage and checked the pressure.everytime i turn the key to on i hear the pump run about three seconds.the first time the guage doesn't move at all.after five times the pressure is up to fifteen but drops immediatly.the pump runs three seconds each time.i raised it to look for leaks but i don't see any.1991 4.0.
Lead Driver
Joined: Sep 2003
Posts: 7,013
Likes: 204
From: SoCal
Sounds like the fuel pressure regulator is not working properly. Pull its vacuum hose to see if there's gas in it. If so, its diaphragm has ruptured, and all that fuel that's supposed to be pressurizing is going into the intake manifold. Otherwise, it's bypassing too much fuel back into the tank.
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Tuned
Joined: Sep 2007
Posts: 455
Likes: 6
i put a vaccum on the regulator and it held at 21 psi.it also turns out the vaccum line hooked to it was the one that i found unhooked on the other end but i left unhooked because i couldn't tell where it was supposed to go.so i hooked the guage directly to the output of the fuel filter.it did exactly the same.i assume the fuel pump has a check valve in it so since it bleeds right down the problems in or above the tank.
Tuned
Joined: Nov 2011
Posts: 306
Likes: 15
Tranny dumping when hot, had the same thing couple years ago. Had to bite the bullet and have it pulled at the shop and fully resealed, went ahead and let them replace the torque converter while it was out. It wasn't cheap, I guess the front seal could just be changed, but I wanted the full seal job
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cleanstreak
Ford Inline Six, 200, 250, 4.9L / 300
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Apr 3, 2003 07:23 AM
