Fuel System Issues.... - JeepForum.com
 
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post #1 of 10 Old 09-16-2012, 01:02 PM Thread Starter
94LaredoV8
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1994 FSJ Cherokee 
 
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Fuel System Issues....

Hey everyone, new to site, hoping I can find someone who has had the same issue, and possible solution to my problem. I have a 1994 Grand Cherokke Laredo, starting a few months ago when key was turned to on (engine still off) I would hear a clicking sound coming from the fuel pump relay. Eventually the clicking would slow down before the pump finally primed, then I could start no problem. Then it got so bad the clicking wouldn't stop, no matter how long I left it "on". Took it to the repair shop and connected a pressure tester to the rail, and found air in the lines. Bled the air out, installed new battery and checked all plugs, ran fine for a week (no waiting for fuel system to prime) then the clicking started again. Now won't start. So far have installed new filter, new pressure regulator, and 2 used fuel pumps. Now I'm back to waiting for fuel system to prime, but once it does I only have about 10psi on the rail. Is it possible 3 pumps in a row have had the same issue?

Any help would be much appreciated, and if more detail is required, just ask and I will tell you what I can.

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post #2 of 10 Old 09-16-2012, 02:33 PM
dylantheheeler
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Location: Smithville, Texas
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Swapped the horn and fuel pump relays yet?

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post #3 of 10 Old 09-17-2012, 09:30 AM Thread Starter
94LaredoV8
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have switched all relays and fuses. at this point im not sure if there is a restriction in the lines, or a leak somewhere. a friend of mine with the same model/year as my jeep said sometimes the lines INSIDE the fuel pump module will crack/wear out. so thats my next step, drop the tank again and take the pump to his repair shop.
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post #4 of 10 Old 09-17-2012, 12:26 PM Thread Starter
94LaredoV8
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1994 FSJ Cherokee 
 
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found the pressure problem! finally! had a hunch to remove the new fuel pressure regulator, when i got it out, i found that when it was installed the tip (on the rail side) got bent, and they left the extra "O" ring on it. straightened it out with an awl, and removed the extra "O" ring. Boom! 48psi. woohoo!
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post #5 of 10 Old 09-17-2012, 06:17 PM
dusterdude
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Cool deal dude
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post #6 of 10 Old 09-18-2012, 05:59 PM Thread Starter
94LaredoV8
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1994 FSJ Cherokee 
 
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unfortunately still have to wait for system to prime, along with clicking noise. someone at the shop said a relay clicking means no power. its a brand new battery, so should i look for a frayed wire, or a short somewhere? and if so any advice on where to start looking?
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post #7 of 10 Old 09-18-2012, 07:33 PM
ZeeJay1997
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Quote:
Originally Posted by 94LaredoV8 View Post
a relay clicking means no power.


Low power maybe?

ECM furnishes ground to activate the coil when ignition switch start/run is furnishing the high potential for coil activation. This closes the contacts to send B+ to pump.

if either the ground or ignition voltage is weak, it could be that the coil is at threshold between activate and deactivated, causing it to click

Suggest looking at the schematic on the relay and running the voltages down. Then jump across the sockets for the relay contacts to simulate a closed relay to test the power circuit.
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post #8 of 10 Old 09-18-2012, 08:29 PM
newfieZJ
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1995 ZJ 
 
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Posts: 6,557
Try searching bad caps in PCM , or bad capacitors . There's even a write-up somewhere on here . One of the finds will have some symptoms listed . Can't say for sure , but it sounds familiar .
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post #9 of 10 Old 09-27-2012, 01:01 PM Thread Starter
94LaredoV8
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1994 FSJ Cherokee 
 
Join Date: Sep 2012
Location: belhaven
Posts: 5
coil is working fine, but its the fuel pump relay that is clicking, i even hooked up an old snap-on scanner, and kept getting "the vehicle is not responding, try...." all my fuses are good, and as far as i know so are the relays, bad pcm perhaps? took it out yesterday and happened to leave it in the sun for a while, on a hunch i put it back in while it was hot, and my issues seemed to abate, though as soon as i let it sit overnight, the problems returned. idk if it works like a desktop, but i know when they get old, they wont work cold. if a new pcm would solve these problems, i would be ecstatic. it runs great...while its running, the longer it sits, the more a pain in the *** it is to start up. going on 5 hours so far today and still not running. as it stands im starting to get fed up with the damn thing. UGH
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post #10 of 10 Old 09-27-2012, 05:32 PM
newfieZJ
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