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Fuel pump

823 views 5 replies 6 participants last post by  Siva283 
#1 ·
My 93 4.0l Wrangler has been acting up lately after a ton of frustration the shop had determined that the brushes in my 2 year old carter fuel pump were wearing out causing me not to start randomly at times and of course it was one year out of it warranty period. So I replaced my fuel pump with a new carter pump and a purolator fuel filter. After getting everything back together, I had a rather hard time getting it to start, I tried about 4 times, added some gas, figured I was out, tried two more times, rough start but it fired up, I let it idle then filled up at the gas station, on my way to the gas station, under acceleration i could really feel my jeep take off when i broke about 2,000 rpms, I was happy, added in some marvles mystery oil in the fuel. Had a little hard time to start, cranked about twice then it fired up. I did the poor mans prime through out the week, it was hard to start on cold starts, and about two cranks with my foot on the floor during warm, thought maybe i had a leaking injector. Today as I was driving it I began hesitating and loosing power during acceleration, I couldn't go about 3,000 rpm, then it trickled down to 2,000 thousand, and lower then died in the middle of the road, had to get towed home, it would crank over but run super rough like it was starving for fuel, had about a half tank of gas, and could hear my pump prime. I thought My injectors must be clogged (I just picked up one from the auto parts store). I played around with the oem cps and bwd cps, same with the fuel pressure regulator, nothing. Tried starting fluid, fired then died. I check my fuel rail by depressing the valve, very little trickled out, I tried priming it a few times and starting, sometimes it would almost start, still no pressure in the line. I'm now assuming my new pump is dead! Anyone deal with this before?
 
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#3 ·
You need to do a fuel pressure test at the fuel rail. Get yourself a fuel pressure tester. Not much money.
It ought to have 31 PSI at idle.
It should jump to 39 PSI with the vacuum line removed from the fuel pressure regulator.
If you momentarily pinch off the rubber return line the pressure should quickly exceed 75 PSI.

See what you get for reading and report back.
 
#4 ·
You did not state you added fuel.

Just for the heck of it throw in a few of gallons of fuel. My buddies 93 was acting up with 1/2 tank gas showing. our fuel gauges suck. Start simple. You could be just at the fuel line and the gauge is stuck as does happen. So it acts funny!
 
#6 ·
He did add gas. It was in the middle of his paragraph though.

Op do the fuel pressure test mentioned earlier. You can rent a fuel pressure gauge from auto parts stores when you return it you get all your money back

Sent from my SPH-L300 using JeepForum
 
#5 ·
Just another though to look at. When you replaced the fuel pump, did you happen by chance to pinch the fuel line between the fuel tank and the jeep body? If the lines aren't taped in place they can move around while reinstalling the fuel tank.
 
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