Weak fuel pump?
Thread Starter
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Tuned
Joined: May 2017
Posts: 284
Likes: 42
From: Colorado
Weak fuel pump?
I think my fuel pump may be tired. Just seeing what you guys think
My fuel pressure is dropping under load empty. When climbing a 6% grade on hwy, pressure was dropping to 40-45 psi.
Did a little test on it today
Idle
Pre filter - 58 psi
Post filter - 54 psi
Taking off normally from red light
Pre filter - 54 psi
Post filter - 50 psi
Stepping on it passing on hwy
pre filter - 50
Post filter - 40
Haven't looked at fuel filter yet
Got about 10-12k on this fuel filter. Ordered a couple more. Was pretty clean last time I changed it.
With a clean filter, does any one know what the psi drop should be between pre and post filter?
Thanks
My fuel pressure is dropping under load empty. When climbing a 6% grade on hwy, pressure was dropping to 40-45 psi.
Did a little test on it today
Idle
Pre filter - 58 psi
Post filter - 54 psi
Taking off normally from red light
Pre filter - 54 psi
Post filter - 50 psi
Stepping on it passing on hwy
pre filter - 50
Post filter - 40
Haven't looked at fuel filter yet
Got about 10-12k on this fuel filter. Ordered a couple more. Was pretty clean last time I changed it.
With a clean filter, does any one know what the psi drop should be between pre and post filter?
Thanks
Cargo Master
Joined: Sep 2015
Posts: 2,860
Likes: 365
Sounds like your filter might need changed, check to make sure it's not black. I have a slight injector o ring leak which is turning my filter black and clogging it up. Was experiencing same issues as you but after a filter change it helped out the fuel pressure drop under heavy load. Another issue might be your in tank pick up screens if you haven't done the hutch mod yet. Start with the easy stuff first
Thread Starter
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Tuned
Joined: May 2017
Posts: 284
Likes: 42
From: Colorado
Thanks for the replys.
I have Riff Raffs FPR with the gold spring, Hutch/Harpoon also done w/ racor on frame. Really no air bubbles in racor at idle
I haven't checked fuel filter yet, was just going to wait for the new filters to come in and just change it . Anyone know pressure drop from pre to post?.
I guess I could also try the black spring for the FPR,
So it sounds like no one think it's the pump. Since truck was empty, and I saw it dropping that much, I thought it would be the pump.
I have Riff Raffs FPR with the gold spring, Hutch/Harpoon also done w/ racor on frame. Really no air bubbles in racor at idle
I haven't checked fuel filter yet, was just going to wait for the new filters to come in and just change it . Anyone know pressure drop from pre to post?.
I guess I could also try the black spring for the FPR,
So it sounds like no one think it's the pump. Since truck was empty, and I saw it dropping that much, I thought it would be the pump.
Lead Driver
Joined: Jul 2017
Posts: 6,861
Likes: 2,335
From: WV
Thanks for the replys.
I have Riff Raffs FPR with the gold spring, Hutch/Harpoon also done w/ racor on frame. Really no air bubbles in racor at idle
I haven't checked fuel filter yet, was just going to wait for the new filters to come in and just change it . Anyone know pressure drop from pre to post?.
I guess I could also try the black spring for the FPR,
So it sounds like no one think it's the pump. Since truck was empty, and I saw it dropping that much, I thought it would be the pump.
I have Riff Raffs FPR with the gold spring, Hutch/Harpoon also done w/ racor on frame. Really no air bubbles in racor at idle
I haven't checked fuel filter yet, was just going to wait for the new filters to come in and just change it . Anyone know pressure drop from pre to post?.
I guess I could also try the black spring for the FPR,
So it sounds like no one think it's the pump. Since truck was empty, and I saw it dropping that much, I thought it would be the pump.
The low pressure is a new development correct?
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Lead Driver
Joined: Sep 2010
Posts: 7,793
Likes: 50
Somehow, crap got passed by the inline filter, clogging up the pump inlet..figuring, it worked hard and compromised its life, I obligated to toss a new 1 in
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5th Wheeling
Joined: Jan 2022
Posts: 48
Likes: 10
What's the temperature right now where you live? If it's below freezing, are you using anti-gel additive?
I had a very similar problem that behaved much like missing at high rpms and the anti-gel additive took care of it.
I had a very similar problem that behaved much like missing at high rpms and the anti-gel additive took care of it.
Thread Starter
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Tuned
Joined: May 2017
Posts: 284
Likes: 42
From: Colorado
Going to try and replace fuel filter 1st.
Are there any other tests on the fuel pump I can try?
Lead Driver
Joined: Sep 2010
Posts: 7,793
Likes: 50
Coffee hasn't kicked in yet but only thing that comes to mind is, remove inlet hose to pump, and inspect the pump spigot...thats where the crap was built up on mine(after I'd already removed pump)....
if nothing there then I'd change bowl filter and hit the pavement, checking pressure at various throttle positions
if nothing there then I'd change bowl filter and hit the pavement, checking pressure at various throttle positions
Fleet Owner
Joined: Jun 2004
Posts: 25,090
Likes: 1,112
From: Rio Rico, AZ.
What's been mentioned multiple times already in this thread, check the inlet of the pump. There is a screen inside that get's clogged. No good way to clean it thoroughly. There needs to be a replaceable cartridge filter between the tank sump and the fuel pump, IMO. Raising the fuel pressure will do nothing to alleviate the problem. What you are dealing with is lack of fuel VOLUME not pressure under load. Need to get that fixed and you'll have your truck back.
Hotshot
Joined: Nov 2006
Posts: 11,288
Likes: 269
From: North of Greenville
Can also remove the inlet line to the fuel pump (suction side), and blow backwards through that line into the tank. If your pickup foot has crumbled or if you've gotten trash in the tank, it can get caught up at either the inlet to the pickup tube itself, or in the 90° bend coming out of the top of the tank. If you get good airflow blowing through the line into the tank, you'll hear the aggressive gurgling when you do this and then you'll know the line is open.
If the above resolves your issue, then plan to run the tank down near empty, drop it, and then clean out the tank and replace the plastic pickup foot (if you're still running one).
If the above resolves your issue, then plan to run the tank down near empty, drop it, and then clean out the tank and replace the plastic pickup foot (if you're still running one).
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