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  #1  
Old September 30th, 2019, 16:45
vabeachtennis vabeachtennis is offline
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Fuel Issue?

1996 XJ 2WD 4.0 engine with 235k miles on it.



Well, I got one problem solved (flex plate), then another problem solved (water pump and AC compressor), and now I have another problem. Here's the problem:
I was driving down the highway and the Jeep almost cut out on me, I pulled over to the shoulder lane, and the Jeep came back to life and was normal. I pulled off of the interstate and took the back roads to pick up my wife. We took the highway back home and it was fine. I stopped to get a fuel filter and it idled fine for the few minutes I was in the store. We made it home fine.



I turned the Jeep off and then restarted it and the rpm's were only around 400 to 500rpms. Has this happened to anyone? These people want an arm and a leg to replace the fuel pump (if that's the problem). I have received quotes ranging from $300 to $600. My fuel pump is the 1995 version (side of tank) and not the 1997 and up versions 9 top of tank).



Any advice would be greatly appreciated!
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  #2  
Old September 30th, 2019, 17:24
lawsoncl lawsoncl is offline
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Re: Fuel Issue?

By cutting out, do you mean like someone turned off the ignition versus stumbling and sounding like it's running out of fuel? The usual suspect for this is the crankshaft position sensor. Since you just had the flexplate replaced, I would inspect the wiring to the sensor for damage and make sure nothing is laying against the hot exhaust manifold. If the mechanic didn't remove the sensor from the bellhousing before pulling the tranny, it's quite possible he damaged the wiring or the end of the sensor.
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  #3  
Old September 30th, 2019, 18:39
vabeachtennis vabeachtennis is offline
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Re: Fuel Issue?

Quote:
Originally Posted by lawsoncl View Post
By cutting out, do you mean like someone turned off the ignition versus stumbling and sounding like it's running out of fuel? The usual suspect for this is the crankshaft position sensor. Since you just had the flexplate replaced, I would inspect the wiring to the sensor for damage and make sure nothing is laying against the hot exhaust manifold. If the mechanic didn't remove the sensor from the bellhousing before pulling the tranny, it's quite possible he damaged the wiring or the end of the sensor.

It's kind of hard to describe; I thought it cut out but I didn't have to turn the key to start it back up. It seemed like it caught itself and snapped back into action. I just came back in from starting it up and letting it run. It started fine and ran fine but the rpms were getting lower and lower (500 rpms). I turned it off and restarted it the second time and it idled at 700 but then it slowly went down to 600 or 500 rmps. I hear the fuel pump running , when I hit the gas it was fine and didn't stall when I took my foot off of the gas after revving it.



Thank you for your reply, I will check the wiring out tomorrow morning.
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  #4  
Old September 30th, 2019, 19:08
Heavyopp Heavyopp is offline
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Re: Fuel Issue?

Buy or rent a fuel pressure gauge and check the pressure at the rail

96 is the bastard stepchild of fuel pumps — only a 96 fuel pump can be used
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  #5  
Old September 30th, 2019, 20:01
vabeachtennis vabeachtennis is offline
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Re: Fuel Issue?

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Originally Posted by Heavyopp View Post
Buy or rent a fuel pressure gauge and check the pressure at the rail

96 is the bastard stepchild of fuel pumps only a 96 fuel pump can be used

I'll try to buy one tomorrow and report back.
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  #6  
Old September 30th, 2019, 20:04
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Wayne Sihler Wayne Sihler is offline
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Re: Fuel Issue?

You can get a fuel pump. The rest of the assembly is the problem.The regulator being the main problem
There is an old thread here that explains which regulator fits and how to install it.
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  #7  
Old September 30th, 2019, 21:02
vabeachtennis vabeachtennis is offline
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Re: Fuel Issue?

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Originally Posted by Wayne Sihler View Post
You can get a fuel pump. The rest of the assembly is the problem.The regulator being the main problem
There is an old thread here that explains which regulator fits and how to install it.
Thank you.
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  #8  
Old September 30th, 2019, 21:13
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8Mud 8Mud is offline
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Re: Fuel Issue?

I'd lean towards another issue besides the fuel pump. Logic tells you it needs more fuel to go faster (more RPM) so if you had a fuel issue it would likely show up at higher RPM's before it caused issues at low RPM's.

I never had low idle issues with my 96. But I did have cold motor and warm motor issues. It would run fine when cold as soon as it warmed a bit 3-5 minutes the motor would try to stall, misfire and generally act up. Turned out to be the O2 sensor. the O2 sensor on mine wouldn't throw a code or CEL until it was totally junk and not just iffy.

Check your key codes. The CPS will usually throw a code fairy early when it is beginning to fail. It won't set a CEL though. You may get lucky and the ley code may send you in the right direction, a code reader would be even better.
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Old October 1st, 2019, 04:23
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Tim_MN Tim_MN is offline
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Re: Fuel Issue?

Testing is the primary part of your diagnostics.

Test the fuel pressure.
Test the CPS.
Load Test the Battery.
Test the O2 sensors.

Low fuel pressure, a failing CPS, or a faulty battery can cause the symptoms described.
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  #10  
Old October 1st, 2019, 07:21
vabeachtennis vabeachtennis is offline
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Re: Fuel Issue?

Quote:
Originally Posted by 8Mud View Post
I'd lean towards another issue besides the fuel pump. Logic tells you it needs more fuel to go faster (more RPM) so if you had a fuel issue it would likely show up at higher RPM's before it caused issues at low RPM's.

I never had low idle issues with my 96. But I did have cold motor and warm motor issues. It would run fine when cold as soon as it warmed a bit 3-5 minutes the motor would try to stall, misfire and generally act up. Turned out to be the O2 sensor. the O2 sensor on mine wouldn't throw a code or CEL until it was totally junk and not just iffy.

Check your key codes. The CPS will usually throw a code fairy early when it is beginning to fail. It won't set a CEL though. You may get lucky and the ley code may send you in the right direction, a code reader would be even better.

Thank you, that makes sense regarding the pump. It was actually better when I got on the truck after it almost stalled.



Good point regarding the O2 sensors. I will check the o2 sensor later today.


I hooked my code reader up to the Jeep this morning and no codes. I started the Jeep up and instead of the higher idle when it is cold and then going down to 700 rpms , it started at 700rpms and was going down to 600 rpms.


I bought a fuel filter and will install it later. One thing I did see was a hose that was down but still connected to the fuel rail. It's the one in between the power steering reservoir and the engine.



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  #11  
Old October 1st, 2019, 07:24
vabeachtennis vabeachtennis is offline
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Re: Fuel Issue?

Quote:
Originally Posted by Tim_MN View Post
Testing is the primary part of your diagnostics.

Test the fuel pressure.
Test the CPS.
Load Test the Battery.
Test the O2 sensors.

Low fuel pressure, a failing CPS, or a faulty battery can cause the symptoms described.

Thank you. I just tried to rent a fuel pressure gauge but Advanced Auto doesn't do, I'll try Autozone next.
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  #12  
Old October 1st, 2019, 09:13
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Re: Fuel Issue?

Check and see if the harness running down the front of the engine isn't cooking on the exhaust manifold. Those are your front O2 sensor wires.
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  #13  
Old October 1st, 2019, 09:16
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Re: Fuel Issue?

That is your fuel in hose- fuel line for the injector rail.
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  #14  
Old October 11th, 2019, 16:36
vabeachtennis vabeachtennis is offline
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Re: Fuel Issue?

Quote:
Originally Posted by Tim_MN View Post
Testing is the primary part of your diagnostics.

Test the fuel pressure.
Test the CPS.
Load Test the Battery.
Test the O2 sensors.

Low fuel pressure, a failing CPS, or a faulty battery can cause the symptoms described.

Closure? I'm superstitious but so far so good. I took the Jeep to a mechanic a couple of weeks ago. He test drove it and thought that there was a fuel issue too and suggested changing the fuel filter (he knows I can do that myself).

I said "thank you" and was about to go on my way and low and behold the Jeep decided to quit right there!They tested t and it turned out to be the CPS, they installed it for $40 labor and I bought the part. I drove the Jeep and it was ok , changed the fuel filter and "voila!" much better!

Then my passenger side caliper decided to stick and piss out on me, replaced that and so far all is well after about 600 miles.


This is a great forum, thank you ALL for your help! I'm sure that I will be asking for more help soon and if I can help others, I will do that too. Have a great weekend and thank you again!
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