fuel problem

what are some symptoms of a crappy fuel pump?

heres the scoop:

- I ran a aux fan over ride switch to the relay on the driver side fender(89 4.0L)..when i messed with that i accidently unplugged that other thing over there ...it somehow controls my fuel pump dunno what it is tho~(fuel ballaster sp*?) (jeep would start and die... found the problem just plugged it back in)

- well ever since i messed with that, if i stomp it and get to 4000+rpm... jeep will sputter and afterwards comming to a stop ill idle at 400-500rpm

- and ever since then if i hit a bump too hard...jeep will die

i ran it low past E this last time b4 puttin gas in, and where i filled up i usually notice my jeep running like crap after wards, but nuthing like this

possibly crappy gas?

well, the easy answer is to test the fuel pressure with a guage at the fuel rail- if it bumps more than 30psi, it should be good. The pump should come on when you turn the key to on, cycle for a few seconds to build pressure, then stop.
Personally, I doubt unplugging the ballast for a few seconds hurt the pump-but running an 89 jeep down to E will probably get you alot of crap stuck on the filter in the tank- if its the original pump/filter-it may be time for the replacement-
a hole lot of crud gets in there over the years--a raindrop here, a clump of mud there....
I`ll vote bad gas first, since its the easiest to check with another tankfull, then a gummed up filter.

i just replaced the fliter no more then 7,000miles ago

its the original fuel pump to my knowledge... but one minute it works perfect..the next im sputtering... just weird

My XJ will only run on 89 or higher octane...and Mobile at that ,anything lower
octane wise n it runs crappy.....
I always change my filter each year,regardless..

JVRacer04 said:

i just replaced the fliter no more then 7,000miles ago

Click to expand...

which filter? Theres two. and if you replaced the one in the tank, and didnt do a new fuel pump at the same time, your nutts. tank filters suck(pun)-its not a fun job, and nobody wants to do it everyday...since you have to remove the pump to get to the filter, you always do a new pump and save the old, hopefully to never use it...but its with you if you do.

the frame rail filter is the catch all when the tank filter fails- the filter sock in the tank has ittybitty small miniscule tiny holes- some say even water cant get through it (which I seriously doubt)-BUT, its also a pretty small filter-clog it, or cut its intake by half, and your pump cant get enough quick enough. It`ll build pressure at idle, it may even cruise down the road nice-stomp it, and it`ll cough up a storm once the injectors use up the pressure.

Older jeeps have tanks with crap in them-you cant avoid the crap- after years of crap buildup, the sock filter fills up....and if its really old, the sock filter tears and then clogs the framerail filter-saveing you money by not clogging up the injectors.

thought the filter in the tank was the strainer?

no i havent replaced it

i replaced the frame rail filter

this problem is really starting to get bad.... i idle so low i wont even read oil pressure, i have to pop it in nuetral and rev it a bit

i thgouht it might be a loose connection so i re-wired everything under the hood for the fuel system, but i still havent given it a test drive yet... got class in 30min tho so ill see if taht works

JVRacer04 said:

thought the filter in the tank was the strainer?

no i havent replaced it

i replaced the frame rail filter

this problem is really starting to get bad.... i idle so low i wont even read oil pressure, i have to pop it in nuetral and rev it a bit

i thgouht it might be a loose connection so i re-wired everything under the hood for the fuel system, but i still havent given it a test drive yet... got class in 30min tho so ill see if taht works

Click to expand...

As somebody already said "CHECK THE FUEL PRESSUE" and give the flow a look too. You also need to qualify the ballast resistor you spoke of disconnecting. If that has been damaged it could have weird driveability issues.

Did you see this thread about idle for an '89?

http://www.naxja.org/forum/showthread.php?t=48632

There's about 1/2 dozen things to qualify with Renix EFI. Relatively easy but it's not guesswork. Do you have a FSM? (factory service manual)

i think i found the problem... ive had troubles with this ground wire that goes to the oil dip stick...

everything seems to be normal now... but thank you to all who helped