Fuel Pump Replacement Advice
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Freshman User
Joined: Jan 2016
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Fuel Pump Replacement Advice
Hello,
I believe I have an air intrusion issue with my 1991 F350 7.3 IDI. I can start the truck easily, but then it will sputter and die unless I give it a great deal of fuel. After that initial failure---if I fail to get on the throttle---the truck is next to impossible to start. I replaced the fuel filter, but the problem persists. I intend to change the injector caps, O-rings, and return line (hopefully that job will happen this weekend).
I'm also considering replacing the fuel pump, but I'm nervous as it seems tough to get to, and from what I've read, you need to change the position of the cam shaft. I really unclear on how to do that. I'd appreciate the community's thoughts on whether fuel pump replacement is advisable, and if so, a detailed (idiot's guide) to the replacement.
Thanks in advance for any information. As a side note, I recently got the truck (kind of a dream truck for me), but have very little experience working with diesels or even with Ford trucks.
Respectfully,
Mike
I believe I have an air intrusion issue with my 1991 F350 7.3 IDI. I can start the truck easily, but then it will sputter and die unless I give it a great deal of fuel. After that initial failure---if I fail to get on the throttle---the truck is next to impossible to start. I replaced the fuel filter, but the problem persists. I intend to change the injector caps, O-rings, and return line (hopefully that job will happen this weekend).
I'm also considering replacing the fuel pump, but I'm nervous as it seems tough to get to, and from what I've read, you need to change the position of the cam shaft. I really unclear on how to do that. I'd appreciate the community's thoughts on whether fuel pump replacement is advisable, and if so, a detailed (idiot's guide) to the replacement.
Thanks in advance for any information. As a side note, I recently got the truck (kind of a dream truck for me), but have very little experience working with diesels or even with Ford trucks.
Respectfully,
Mike
Laughing Gas
Joined: Dec 2013
Posts: 884
Likes: 7
Sounds like a good time to switch to an electric fuel pump, it will save your starter and sanity. But if you already have a new mechanical pump, 1. Put vice grips on the fuel lines 2. Ease off to the side and remove the hoses 3. Unbolt pump and wiggle it out. 4. Clean the area the pump may be sealed with silicon, now is a good time to apply good rtv 5. Fandangle the new pump arm into the motor 6. Replace bolts and fuel lines.
Posting Guru
Joined: Jan 2001
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From: Poway, CA
May or may not be worth it, but I know some complain that one of the two fuel pump bolts is difficult to get at. When I installed my electric pump, I unbolted the vacuum pump from its mounting bracket, set it out of the way, and found it very easy to get at everything.
Mike
Mike
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Joined: Dec 2011
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I've swapped the mechanical low-pressure fuel pumps several times on these trucks; both with the vacuum pump in place and removed.
If it's in place, you basically have to do it from under the truck. Otherwise, you can do it from up top.
Either way, it's a 1 hour job, more or less.
I personally am not too impressed with the electric pumps; they are both expensive, and the one that everyone likes(Faucet Duralift) doesn't seem to supply enough fuel at WOT... on my dad's truck, the fuel pressure drops from 7+ PSI to 0 PSI under heavy acceleration.
Either way, if you want to fix things right, delete the return line from the filter head. Ford has a TSB our on removing it, and it helps a lot with preventing fuel from draining back.
For added protection, I have modified the line from the low-pressure fuel pump to the filter and replaced the middle section with a couple bits of hose and a squeeze-bulb primer. It provides two check-valves to keep fuel from going backwards. It also provides a primer if you ever run out of fuel, so you don't need to run the batteries down.
If it's in place, you basically have to do it from under the truck. Otherwise, you can do it from up top.
Either way, it's a 1 hour job, more or less.
I personally am not too impressed with the electric pumps; they are both expensive, and the one that everyone likes(Faucet Duralift) doesn't seem to supply enough fuel at WOT... on my dad's truck, the fuel pressure drops from 7+ PSI to 0 PSI under heavy acceleration.
Either way, if you want to fix things right, delete the return line from the filter head. Ford has a TSB our on removing it, and it helps a lot with preventing fuel from draining back.
For added protection, I have modified the line from the low-pressure fuel pump to the filter and replaced the middle section with a couple bits of hose and a squeeze-bulb primer. It provides two check-valves to keep fuel from going backwards. It also provides a primer if you ever run out of fuel, so you don't need to run the batteries down.
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Freshman User
Joined: Jan 2016
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Thanks for the return line delete suggestion. I had no idea that could/should be done. I did a quick search and was unable to find a how-to or the original service bulletin. If you have a minute, could you describe how you made the change on your truck?
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Joined: Dec 2012
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From: western washington
install a cheap fuel filter before your e pump on suction side, small debris from tank is what will kill your pump most fuel pumps that go bad or don't seem to pump enough probably have a pine needle stuck in the check valve inside the pump every time I replace a pump for a customer I install a filter before the pump.. and break apart the (bad) pump to find the debris that made it fail...work smarter not harder.
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Freshman User
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I replaced the lift pump, injector caps and o-rings. Sadly that didn't fix the problem. However, I did find an issue with the filter return line check valve (the connection point on the filter for the return line). The check valve was gone---I could see all the way through it. Got a new one from the dealership for $25 and that seems to have fixed the problem. Thanks for all the help and advice.
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