ferm, I need help

spareparts · #1 07-04-2008, 09:15 PM

Ferm, My Cherokee is giving me a fit. Some one sugered my tank last week, i drove it home before i noticed the suger around the neck. i pulled the tank, cleaned it out, replaced teh fuel pump, fuel pump screen, and the fuel fiter(ended up doing it three times, ran great in short distances, changed teh fuel filter again and it did better. i tried to drive up to NC today, only got as far as Myrtel Beach, my jeep was acting like it was starving for fuel. I made it back to George Town, found an Auto Zone, check the codes, 171 and 172, too rich, too lean. I put together a make shift fuel pressure guage and drove it down the road, fuel presure stayed up whgh, then droped fast, Its definately a fuel delivery issue. I pulled one injector and checked the sceen, nothing I could see in it. I'm thinking I got a bad fuel pump, thinking about checking the harness plug for voltage drop. Any ideas? I allready tried running it with the fuel cap off. Anyhting I was missing about installing the fuel pump?

THEFERMANATOR · #2 07-04-2008, 09:40 PM

What year is yours again? If it's a 96+ there isn't to much you can do for the installation, pretty well just drop em in. The 91-95's had issues with the fuel line going from the pump to the metal line inside the tank with it coming off unless you used FLUROMASTER fuel line. As far as aftermarket pumps go, THEY SUCK! I go through one every 3 weeks in mine if I drive it much at all. I put a factory one in it and it only lasted 53 weeks(just made it out of warranty by 8 days

). What was your fuel pressure? Should be 32-39 on a 91-95, and 48 on 96+.

tsubaki · #3 07-05-2008, 06:20 AM

Few months ago my '96 smutted the plugs.
After replacing them, it still didn't improve. The codes came back the same, too rich, too lean.
I replaced both O2 sensors and that then let me clear the codes.
Problem was it didn't recognize an O2 sensor malfunction, but it worked!!
By the way, I do not have an in-line fuel filter on mine (didn't come with it). Apparently the only one is on the fuel pump!!
OH by the way, on most Chrysler products, a loose gas cap will definately set off the check engine light!!

spareparts · #4 07-05-2008, 09:16 AM

Its a 95 4.0 HO. I can't remember exactly what the fuel pressure was, but it was higher than I thought it would be, 50 lbs?. The problem showed up before I replaced the pump, I replaced the pump figureing it was the problem. It will run good for a while, then start acting up. I can shut the key off, let it sit for a few miniutes, crank it back up and it will run good for a few nmiles, then act up again. I swear it sounds like a blockage. The fuel pump will reach fuel pressure, when it starts acting up, the pressure drops, I can feather the throttle while watching the fuel pressure gauge(had it tied to the windshiled wiper) and I can get it up to speed sometimes, just incresing the throttle little by little, looking for the guage to drop. I could never get it above 55 without it lean popping(I think that is what was causing the codes). I seems to be a volume issues rather than a pressure issue. I'm going to replace the rubber fule lines, blow the steel lines out. Drop the tank and make sure I put the pump in correctly.

spareparts · #5 07-05-2008, 09:19 AM

one more thing, while I was working on teh tank, I ran accross this funny looking rubber piece. It looks like a rubber stopper with a hole thru teh center. While i was inspecting teh pump assembly, I noticed teh return line was shinny at the end like it had something slid over it. I hadn't seen teh rubber piece before, it was laying on the ground wher I was working, it slid right over the end of the retuen line and semed to fit right where the return line runs back in the tank. Is this supposed to be there?

tsubaki · #6 07-05-2008, 09:43 AM

For a few months after getting mine it would start sputtering about 45 seconds after cranking up and straighten out less than a minute afterwards.
I was convinced it was the plugs, then the fuel filter, then the fuel pump, finally thought it was the engine computer.
Ended up being the distributer cap needed replacing, once that was done it fixed the problem.

spareparts · #7 07-05-2008, 12:24 PM

i think I figured it out. I replaced the fuel lines this morning and it didn't affect it. I went back and droped the tank, I went back to square one. Whne I pulled the pump assembly out, I was asounded how much crap was on the screen, I had just replaced it with a new one. So mind reals back thru the evnts that had transpired. Yesterday morning, I went to fill teh tank, it had only 5 gals in it before. When I filled it, gas was leaki8ng out of the seal from the fuel pump assmebly. I had pinched the oring. I went back to the house and threw buckets under the car to catch the liquid gold spilling out. I thought the buckets were clean( i was in a hurry),apparently they were not. I dumped the gas, found all kinds of crap in it, cleaned the tank again. Installed a new pickup, put it all back together and now it runs great, Oh well, a lesson learned

randlemanboater · #8 07-05-2008, 03:34 PM

Glad you got her worked out Spare.

Speaking of Georgetown, I went to Kindergarten 1st and 2nd Grade there.

THEFERMANATOR · #9 07-06-2008, 02:10 PM

Glad you got it figured out, I was at the race yesterday so I wasn't able to check in. Yes that rubber piece goes over the return line pipe on the bottom of the unit, and it sit's inside of a metal base on the inside of the tank to hold the assembly in place. If you don't have it in the metal base it WILL leak around that O-ring as it will not be square inside the hole. It will also cause the gas guage to give false readings on a regular basis. Sounds to me like you have a blockage that was caught inside your regulator as your fuel pressure should be roughly 30-32 at idle, and 38-40 at WOT.

I hope you dropped the tank when you did it, if you didn't it is nearly impossible to line up the return base inside the tank with that rubber stopper and drop it in. Learned this one the hard way. I didn't drop the tank and it ended up breaking the solder's on the metal tubes where they pass through the metal plate and had some MAJOR fuel leaks with a full tank. If your pressure was spiking to 50 then it wouldn't be a bad idea to check the inside of your regulator for trash.