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91xj fuel issues

Dingo509

NAXJA Forum User
Location
Yakima, WA
I'll start by saying i have a mechanical fuel pressure gauge installed so i can watch pressure when I'm driving. And over the last couple years i have noticed that in the cold winter months the pressure starts at around 30 then slowly rises up to around 40, right where it should be. It has done this for the last 3 winters. i always but it off till spring when its warmer, I don't have a garage to work in. then of course the pressure is fine and i forget about it.

Well this winter is has dropped to about 20psi, it still runs but i have no power (obviously) but the pressure is dropping a little more everyday. And it does NOT come up with engine temp like before.

I'm positive it needs a new pump. However since it is the middle of winter and we have a 8" of snow on the ground, including under my jeep where i have to work. I am looking for some temporary fixes to get my till spring when i can remove the pump assembly and rebuild it.

My biggest question is does anyone know if i disconnect the wiring on the factory pump, and install a temp external pump will it be able to pull thru the factory pump?

could there be anything else causing this that I'm missing?

And i know the best pump is a Bosch, but does anyone have the exact p/n for it? all the parts houses want around $150-$200 for a crap pump but the Bosch dealer in town only wants $91 for the Bosch replacement pump.

anybody have the Bosch p/n for the higher flow replacement pump?

OK that's enough questions for now. Thanks for the help

Dingo
 
If you have evidence of fuel pressure issues getting worse and you're out of spec per factory numbers, I'd get a new pump in there so you're not left stranded. A lot of winter left to put this off.
 
Have you replaced the inline fuel filter, which is external to the tank on the driver side frame rail? If not, I would definately replace that as it may buy you a little flow and pressure and get you by to warmer weather. It will take you about 10 minutes to replace. Check the condition of the short rubber hoses that connect it, before you go to the parts store; you may need a few inches of hose and some clamps too. I have seen these filters priced from $6 to $25.
 
Syphon fuel to below 1/2 tank. Get a new "O" ring from the dealer, 'bout $6-7 and watch it real close as they like to pouch out during install. (grease 'o'ring with vasoline)(push back into groove with a smooth tool like a popcicle stick while slowly tighting lock ring)

Be sure to use jackstands and safety first, and raise rear of jeep for working room.

Check the short hose on the pump itself to outlet tube is clamped good and secure.

Be gentle with the pump assembly, should NOT have to force at all. Try different angles, remember how you got it out, new one is reverse.

change the fuel filter while you have jeep up and its easy to do

Not a bad job and goes quickly, but be Extra careful.

Good Luck,
Orange
 
The bottom of the fuel pump assembly has a rubber 'stopper' that fits into a hole inside the tank. if it misses the hole, then the flange of the mounting plate will have a gap on one side. If all is OK flange is flat against tank ready for lock ring.
 
There are lots of "how to replace pump" threads.
..
You asked about a temporary fix.
I believe the answer is no or maybe.
.
If you put a temporary fuel pump in-line with the fuel filter, and
the internal pump is not running, an external pump cannot pull fuel through it.
.
If i was stuck with no fuel pump running in 6 inches of snow, I might do this.
But it poses danger.

Buy a motor boat portable fuel tank, connect an external fuel pump to it.
Disconnect and plug the in-vehicle tank line
Let the fuel regulator drain the extra gas back to the normal gas tank.

FYI, the pump mentioned in a previous reply is not an exact replacement.
Be prepared to spend more time than you'd expect during the replacement.
http://www.naxja.org/forum/showthread.php?t=983318&highlight=fuel+pump+noise&page=2
 
Temp fix ok for trail or emergency.
Its a Long way to Spring, best to just do it right and one time.
Not hard to do.
 
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