fuel pump problems

fourwheelerjeff · May 18, 2009

i have a 91 xj (4.0/aw4/231) that i am having fuel pump problems with. due to a divorce this cherokee sat for over 2 years. once i got it back, the fuel pump would not work, i figured it just went bad while sitting, so i replaced it. ran good. sat for another couple of days and wouldn't start; fuel pump not working. got another fuel pump and replaced and started right up, sat again for a week and now won't start again.
these are lifetime warranty fuel pumps from advance auto.
any idea's??
thanks in advance.

joe_peters · May 19, 2009

Probably not the pump?

How did the fuel in the tank look/smell?

Have you checked all of the connections in the fuel pump circuit? Tried swapping the relay? Do you still have the POS ceramic on the DS fenderwell--and have you tried jumping it?

fourwheelerjeff · May 19, 2009

resistor has 1.3 ohms of resistance. checking the weatherpack connector for the pump by inserting my leads into the hot and ground, i get 13 volts. can't hear the pump run.

fuel was a mixture of old and new.

gonna try to jump the resistor and see what happens.

fourwheelerjeff · May 25, 2009

another new fuel pump, drained the fuel out, fished 2 old screens out of the empty tank, added fresh fuel, took resistor off fender and cut and spliced wires together. so far after 3 days, no problems.

beakie · Jun 5, 2010

reviving this one 'stead of starting my own.

my '97 rig sat most of winter and has not been able to start up in about 4 months.
if I drop some fuel straight into the throttle body it'll fire up, but then dies once that's gone.

I've disconnected the pump, and tried feeding it 12v straight from the battery to get it to feed, but no go.
next will be pulling the pump to look see...

any ideas?

joe_peters · Jun 5, 2010

You need to check and see if you are getting an impulse signal to the injectors--$3 NOID light at most part stores.

beakie · Jun 6, 2010

noid light, ok sounds like a plan.

now, would the lack of said "impulse signal" cause a lack of action from the fuel pump?

just thought I'd add, normally when you move the key to ignition ON, you'd hear the pump prime, right? I do not hear that, I used to, but since this no start problem has arose, no sound of priming.

thanks for the help

joe_peters · Jun 6, 2010

If you aren't getting a "prime" to the fuel pump I would start testing at the ASD relay, it provides the 12 volts input to the primary side of the coil and the power to the fuel pump for the prime.

However, what happened when you gave the pump 12 volts direct from the battery? I must have misread, as I took it that the pump ran, but you still didn't get FUEL into the cylinders. So, will the pump run when jumped?

beakie · Jun 7, 2010

when the pump is jumped via 12v live... nothing, not a sound. that's my reason for thinking of pulling it to have a look see. it's a relatively new pump (3 years old) however the fluid in it has been sitting for about 7 months (-30* over the winter at times) so... any chance it fubar'd the pump?

I looked up the NOID light tho, and have found plans to build your own to suit your needs, so I'll look into that whether I need it or not.

joe_peters · Jun 7, 2010

Ok, check the ground at the pump/tank, check for power there too. If you have both, I would say pull the pump assembly and see whats up.

Could have been fubar'd sitting in that kind of weather, seems a little remote to me. Any little toothy critters in your neighborhood? Might have had some wires chewed.

beakie · Jun 8, 2010

well the pump works, took it out, fed it direct 12v and it flowed no problem.
so now it's onto figuring out if 12v is being fed to it from the Jeep itself.
I can't seem to find one of my multimeters, and my backup I just noticed is pooched.
I'll pick up another asap and figure things out.
thanks for the help thus far, much appreciated.

fuel pump problems

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