low fuel pressure?!?
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low fuel pressure?!?
Hey all. I recently noticed I have low fuel pressure. At idle when I start my truck, it sits at38-40 psi. When I take off, it slowly rises to around 48-50 psi. It will drop instantly to 40psi when I give it more than half throttle or step on it
I have an air dog 2 as my pump. I changed the filter on that And drained the seperator. Replaced the filter on top of the motor. Replaced the regulator spring. That bumped my Psi up two lbs. But it still drops to 40 anytime I give it more than half throttle. Any ideas fellas?
I have an air dog 2 as my pump. I changed the filter on that And drained the seperator. Replaced the filter on top of the motor. Replaced the regulator spring. That bumped my Psi up two lbs. But it still drops to 40 anytime I give it more than half throttle. Any ideas fellas?
Lead Driver
Joined: Sep 2007
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From: Scio, OR
Is the ADII electric? If so, it would seem that about the only explanation is that the pump is not getting proper voltage at idle or low RPM's, which would point to a problem in the charging system.
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I have not adjusted the screw on the AD2. I loosen the nut, then turn the screw in or out? Does you know which wire is the power wire for the original fuel pump? When I installed the pump, I temporarily got power from the MAP sensor lol. I forgot about it until you mentioned not enough power. IT worked fine until 2 weeks ago on the way home. I could feel it had low pressure. It was a slug. The fitting on the filter housing is tight no leaks. I replaced the O-ring on the regulator about 3 days before this began. It had a small leak. Thats the scoop. What should I check out? I emailed pureflow, but they dont seem to be in a hurry with their reply.
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I heard from pureflow today. They instructed me to remove the petcock on the water seperator. There is a screen on the other side that I need to remove. Then put the petcock back in. So ill try that this afternoon...
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Well. I removed the seperator filter and removed the petcock under it and removed the screen as told. But the problem still persists. Any ideas guys? The pump sounds just as it always has. Its always been rather loud. Anyways, thanks for the help fellas.
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BTW Im gonna check on the wiring part of it tomorrow. I ran out of light and have stuff to do. Ill jump on that first thing
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Hotshot
Joined: Dec 2003
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From: Stuttgart, Ar
I have not adjusted the screw on the AD2. I loosen the nut, then turn the screw in or out? Does you know which wire is the power wire for the original fuel pump? When I installed the pump, I temporarily got power from the MAP sensor lol. I forgot about it until you mentioned not enough power. IT worked fine until 2 weeks ago on the way home. I could feel it had low pressure. It was a slug. The fitting on the filter housing is tight no leaks. I replaced the O-ring on the regulator about 3 days before this began. It had a small leak. Thats the scoop. What should I check out? I emailed pureflow, but they dont seem to be in a hurry with their reply.
Elder User
Joined: Mar 2005
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From: Denison, Tx
You said you replaced the regulator o'ring are you talking about the stock regulator on the top of engine? I had this off to install BB mod and lost the piece behind the spring, after putting it back together had similar issues. Finally pulled back apart and it was missing, found it in engine valley replaced and pressure back to normal. Just a suggestion..
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From: Denison, Tx
The ADII comes with a book that tells you how to adjust the fuel pressure. Loosen the nut and turn the screw in to raise the pressure, but you should NEVER tighten the adjusting screw all the way down and DON"T go in more than 5 turns if it will even go that far. You should have no reason to. If you replaced the o-ring on your regulator cover just before this problem started I would look there to see if the spring and poppet are in the correct position. I bet that's where your problem lies.
OOps you already caught that,,,
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I just replaced the spring thinking that maybe it had shrunk. The new spring was 3 coils longer. The spring fit nicely inside the plastic cup and the machined groove on the cap. I'm 100% positive it went back together right. The new spring gave me 2-3 psi improvement. But still same story. I replaced the gasket that looks like a thermometer. It fixed my fuel leak that I had. A few days later while driving down the highway, I just so happened to look at my gauge at the exact time I watched it drop to 40 psi. My guess is its a problem with the pump? I'm hoping at least. Thanks for your suggestions. Please keep them coming.
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And partsman... Ill adjust the screw a few turns in the AM and see if my problem gets better. I called pureflow. They said it should have been at 60psi from the factory. But mine has always been at 50??
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