Update #3: It's the fuel pump

BSD · Dec 20, 2005

An update on my saga. 88 XJ 4.0 AW4. Stumbling under moderate to heavy pressure on the foot feed. I checked the fuel pressure on the rail. With the vacumn off the pressure regulator it read 20 psi, connecting the pressure regulator made no difference. Pinching off the return hose actually dropped teh pressure, slowly, to about 13 psi. So it looks like it is the fuel pump. I changed teh fuel filter so that is not it.
I need a couple of pointers as I prepare to change it. First, from searching, I will proably change the pick up tube. Does anyone know the diameter? I assume it can be regular gas line? Second, I assume there are no quick disconnects on the fuel tank? Third, does the fuel pump come with a new filter sock or do I need to purchase one? Fourth, I can see the access on the upper half of the front of the tank. Safe assumption that I do not have to drop it? Lastly, any pointers?
I would also wonder if anyone could explain why the Jeep would actually run better in lower gears once it moved above 2200 r.p.m.? Is it because the engine moved into it's most efficient portion of its power curve? If I recall, they are most efficient around 2400 r.p.m.
Thanks again for all the help.
BSD

langer1 · Dec 20, 2005

BSD said:
An update on my saga. 88 XJ 4.0 AW4. Stumbling under moderate to heavy pressure on the foot feed. I checked the fuel pressure on the rail. With the vacumn off the pressure regulator it read 20 psi, connecting the pressure regulator made no difference. Pinching off the return hose actually dropped teh pressure, slowly, to about 13 psi. So it looks like it is the fuel pump. I changed teh fuel filter so that is not it.
I need a couple of pointers as I prepare to change it. First, from searching, I will proably change the pick up tube. Does anyone know the diameter? I assume it can be regular gas line? Second, I assume there are no quick disconnects on the fuel tank? Third, does the fuel pump come with a new filter sock or do I need to purchase one? Fourth, I can see the access on the upper half of the front of the tank. Safe assumption that I do not have to drop it? Lastly, any pointers?
I would also wonder if anyone could explain why the Jeep would actually run better in lower gears once it moved above 2200 r.p.m.? Is it because the engine moved into it's most efficient portion of its power curve? If I recall, they are most efficient around 2400 r.p.m.
Thanks again for all the help.
BSD

Fuel pumps can be had that is the whole drop in unit, or you can get parts.
The pickup tube and sock is a kit.
If you don't get the whole unit you will need to pull yours first because several were used and don't fit the bracket.

Cottontail · Dec 20, 2005

You are correct. You don't need to drop your tank to make the swap.

I am fairly tall (6'6") and thin so I jacked the back of the truck up and set it the tires down on 4x4s I set on the garage floor. Just getting the truck off the ground 4 inches (it is stock by the way) was enough room for my long, gangly arms to work around and pull the pump.

You shouldn't have a lot of problems. My biggest problems were getting the o-ring off the tank. It was kind of rusty. The sock also was loose on the old pump and fell off into the tank when I went to remove the old pump.

It should be an hour (+/-) job depending on the condition of your old hardware, on how dedicated you are to starting and finishing...I sometimes stop for beer...and your mechanical abilities.

Good luck, and have fun with it. It is always nice to learn something new!

againstherwill · Dec 21, 2005

When I was tracking down problems with my project I started at the pump also. Getting to it is not a problem. Getting it off is. Hit it with PB or something like it a day or so prior to trying to remove. As stated above it is a b*tch to get the ring off if it has any rust on it. Also Autozone will rent you a fuel pump puller kit. The kit was really helpful to me as I don't have anyone to help and putting equal pressure on two or more of the tabs. It was nearly impossible. Put the arms of the kit on the tabs turned it with a socket and it came right off. My pump was part of the problem.
Good luck and know that once you have it done YOU will have done it.

churky89 · Dec 21, 2005

And lets not forget........make sure the fuel in the tank is BELOW the opening for the fuel pump........just a reminder,don't want anybody gettin soaked in gas......

badge714 · Dec 21, 2005

Use a brass punch to remove ring, ( DON'T USE STEEL PUNCH ) THEY CAN CAUSE SPARKS WHICH YOU DON'T WANT AROUND GAS TANK. badge714

Nevada City Sparky · Dec 21, 2005

badge714 said:
Use a brass punch to remove ring, ( DON'T USE STEEL PUNCH ) THEY CAN CAUSE SPARKS WHICH YOU DON'T WANT AROUND GAS TANK. badge714

Ain't it the truth! That's how I got my name (boom!)

Update #3: It's the fuel pump

BSD

NAXJA Forum User

langer1

NAXJA Forum User

Cottontail

Three-De Off-Road

againstherwill

NAXJA Forum User

churky89

NAXJA Forum User

badge714

NAXJA Forum User

Nevada City Sparky

Jeeper

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