Fuel pump?

Tiny
DONMCK
  • MEMBER
  • 1998 JEEP CHEROKEE
I have a 1998 cherokee with 111,000 miles. I have been experiencing rough idle and less than normal acceleration for some time. I tested the fuel pump pressure at 47psi, needle has a slight quiver at idle but steadies at speed. Tried to test capacity by attaching hose to the pressure test valve on the fuel rail, unattached the fuel injectors so they would not open, unattached the coil wire and than continously cranked the engine to prevent the ASD relay from shutting off the fuel pump for 7 seconds like it said in the service manual. I got 80ml of fuel instead of the 250ml which it said was normal. The only difference was I did not unattach the fuel line to test and I did not use a DRB scantool to keep the fuel pump running as I do not have one. Is this an adequate test and I can assume the fuel pump needs replacing? It is quite an expensive job. Thanks.
Tuesday, April 10th, 2007 AT 12:04 PM

17 Replies

Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
Well the fuel pump will only run for 4-5 seconds unless you have the tool to keep it pumping! So your test is inaccurate! Attach a pressure tester and see how fast the pressure falls of after you turn the key back to off.
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Tuesday, April 17th, 2007 AT 4:17 AM
Tiny
GPKIDDER
  • MEMBER
  • 1 POST
  • 1996 JEEP CHEROKEE
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 228,000 MILES
My Jeep just died one day doing errands. We check it out on have no fuel pressure, but check the fuel pump and it has 4 wires going it to the fuel pump and one ground. We are not showing any power to any of the wires at the pump. We do have power at the pump relay though. My fuel pump in the 96 Cherokee has a fuel regulator attached to the pump, thus the extra wires. Any suggestion of why I would not be getting power to the pump? Also, this is an old police model that was used by the Michigan State Police. I will take all suggestions?
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Wednesday, July 17th, 2019 AT 2:17 PM (Merged)
Tiny
RLBSTUCKINHOU
  • MEMBER
  • 11 POSTS
Let check the fuses first by using the guide and the fuse locations below. I also have the fuel pump wiring diagrams so you can see how the system works.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Check out the diagrams (Below). Please let us know what you find. We are interested to see what it is.
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Wednesday, July 17th, 2019 AT 2:17 PM (Merged)
Tiny
MTEELE2002
  • MEMBER
  • 1 POST
I had this problem the relay was bad FYI
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Wednesday, July 17th, 2019 AT 2:17 PM (Merged)
Tiny
RAINWIZARD8
  • MEMBER
  • 9 POSTS
  • 1998 JEEP CHEROKEE
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 145,800 MILES
Hey Pros I have a serious problem. I got in my jeep yesterday it started fine, I drove it about five miles, went to get back in in to start it and it would not start. My fuel pump will not get output, I have no fire to the cylinders and my gauges don't work. Let me mention, it will crank and dash lights will work, but I have no fire to engine or fuel pump and gauges are out. I know it doesn't have a crash sensor, so do you guys know where I might have a problem? I have checked the ignition switch, crankshaft sensor and all fuses and relays. You guys helped me once hopefully you can again. THANKS
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Wednesday, July 17th, 2019 AT 2:17 PM (Merged)
Tiny
JAMES W.
  • MECHANIC
  • 2,394 POSTS
Do you power to the fuel pump relay socket?
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Wednesday, July 17th, 2019 AT 2:17 PM (Merged)
Tiny
RAINWIZARD8
  • MEMBER
  • 9 POSTS
I do not, its like it's shut down somewhere between the harness and pump. I also have no fire going to the coil or plugs and my light on instrument panel work, but no gauges do. I have checked numerous things like the Balast resister, ignition switch, neutral safety switch, crankshaft sensor, and shift selector switch, fuses and relays too. Any other suggestions what to check?
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Wednesday, July 17th, 2019 AT 2:17 PM (Merged)
Tiny
JAMES W.
  • MECHANIC
  • 2,394 POSTS
There is a module mounted on the fuel tank that the pump circuit passes through. If fuse # 16 in the underhood fuse block is good and you have power to the FP relay socket, the problem must be with the module.
The dash gauge system is feed with 2 circuits. 1- fuse #16 in the underhood block. 2- #9 in the block behind the right side kick panel.
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Wednesday, July 17th, 2019 AT 2:17 PM (Merged)
Tiny
RAINWIZARD8
  • MEMBER
  • 9 POSTS
I asked a question, about why my speedometer or my fuel pump would not work, well after days of searching for answers and listening to suggestions I found my problem. It was the crankshaft sensor was bad. I replaced numerous sensors and wiring harness and nothing fixed the problem, untill I changed that and my problem was solved.
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Wednesday, July 17th, 2019 AT 2:18 PM (Merged)
Tiny
JAMES W.
  • MECHANIC
  • 2,394 POSTS
Glad you found it. Many times on a Jeep, the CPS will fail and not trip a CE light. If the CPS was out, you should have lost injector pulse also. Problem is, there's really no good way to test them.
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Wednesday, July 17th, 2019 AT 2:18 PM (Merged)
Tiny
PIECE O JEEP
  • MEMBER
  • 1 POST
  • 1994 JEEP CHEROKEE
  • 42,900 MILES
I have a 94 cherokee sport 4.0 liter. With only 42,000 miles. While driving down the road one day it started to spit n sputter like it wasnt getting gas, I assumed it was a problem in the fuel system so I replaced fuel filter and fuel pump and I still have same problem. It will be running fine and then you can hear the fuel pump stop pumping and the engine dies. What the heck could be causing this?
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Wednesday, July 17th, 2019 AT 2:18 PM (Merged)
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
If power supply is cut to the fuel pump, it would not work. You need to check the electrical circuits. It could be the relay, loose connection or a problem with the PCM.
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Wednesday, July 17th, 2019 AT 2:18 PM (Merged)
Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,005 POSTS
Without knowing exactly what's going on.....and maybe you are just making assumptions and sorta grasping for straws, tunnel vision sometimes takes over!

Have you done some actual hands on testing with instruments???---like.....when it is "glitching", what is the fuel pressure and do you have spark???

This kinda info might turn your diagnosis around 180 degrees (and then again maybe not)

Take this post as an example...dead in the water, then it would fire back up later

Http://www.2carpros.com/questions/2001-jeep-cherokee-stalls-cannot-restarted-random

Just to get you to understanding how i approach my jeeps' evil issues, that come about from time to time

Http://www.2carpros.com/questions/2007-ford-taurus-tune-up

I just don't trust "word of mouth" until i can verify it in writing

As far as maybe not having a manual---i can provide you with one.

Performing tests is all a matter of "actually" cracking down and performing them...and getting the proper tools/instruments needed (many times they can be rented at an auto parts store, or a "get by" version might be found at a place like "harbor freight", etc

Looking thru this manual does take a little practice to find stuff....these are the factory manuals, if you had yours in paper, i could say this is the best you could get....see "online repair manual", 2nd block down, in my link

Http://www.jeep4x4center.com/knowledge-base/index.htm

......this is the best i can do for you, right now

Insure you put in the exact information about your vehicle--should your year not be listed....just move up or down a year

Testing is the key as to an expedient and inexpensive repair

Keep us informed as to what you discover or if you have more questions

And yes,..........you do owe us lunch!....pick us up in your "repaired" rig.

The medic
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Wednesday, July 17th, 2019 AT 2:18 PM (Merged)
Tiny
MLISTER
  • MEMBER
  • 1 POST
  • 1994 JEEP CHEROKEE
  • 2WD
  • AUTOMATIC
My Jeep Grand Cherokee just broke down on me going down I-10. It was making a loud clunking sound and heavily vibrating the entire vehicle when it started to break down. Jeep wouldn't accelorate when pushing the gas pedal as far as it would go. The engine sounded like it picked up to its highest gear but didn't accelorate. Anyway, it shut off on me as I pulled over. A pipe coming from the top of my oil reserve and connecting to(I think) the air filter was broken and leaking oil. I put more oil in but the car wouldn't stay on, the engine continued to die back out. A couple times the engine wouldn't turn over and start, but whenever it did it would die in and out. I tried driving again but only made it about 30ft before the jeep shut off again. Also I couldn't accelorate enough that time either. I'm not sure if the broken oil pipe has anything to do with my jeep not running or if its a fuel pump issue (and they just occurred at the same time). What's wrong with my jeep?
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Wednesday, July 17th, 2019 AT 2:18 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
I don't understand why there is so much oil leaking from the air filter other than blow-by. As far as the hose that is broken, that shouldn't cause this problem. The clunking sound makes me believe you were really low on oil, or the engine was overheating. Since it won't stay running, I would recommend checking engine comporession to make sure you didn't blow a head gasket. Also, have a tech listen to the noise to determine if it is a rod or main bearing.
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Wednesday, July 17th, 2019 AT 2:18 PM (Merged)
Tiny
NEIL
  • MEMBER
  • 1 POST
  • JEEP CHEROKEE
Recently, I was driving my 2001 jeep cherokee sport 4.0 I backed out of my driveway, no problem, then put it into drive, got a little squeel from the serp belt when I pressed on the accelerator. I released pressure on the gas pedal and reapplied slowly and it would not accelerate. I slowed down to a stop and turned off the car, then attempted to restart it and it wouldn't fire, it still turns though. Then my odometer pops up saying "no bus". I pushed it into the driveway and then put the keys into the ignition, popped the hood and I could not hear the fuel pump running. Do you think the fuel pump is bad or is it a problem in the power to the fuel pump?
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Wednesday, July 17th, 2019 AT 2:18 PM (Merged)
Tiny
BOB WILSON
  • MEMBER
  • 13 POSTS
You can check the voltage for the fuel pump by removing the fuel pump relay from the control center under the hood. The control center also has a fuse for the pump itself. If the fuse is good, use a volt meter and check the terminals at the fuel pump relay. It should be 12v or very close. There is also a three wire connection near the fuel filter that has a disconect that you can check. Ground your voltmeter and probe the connection terminal closest the the engine. The middle wire should be hot when the key is in the run position.
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Wednesday, July 17th, 2019 AT 2:18 PM (Merged)

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