98 Jeep Cherokee, bad fuel pump or pressure regulator?

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98 Jeep Cherokee won't start at times. I checked the fuel pressure and it is below spec at about 26 psi. It should be 35-45. This has the in-the-tank fuel pump with no external fuel filter. When you pump the accelerator, it will start. I'm told that pumping the accelerator should not make a difference given that the fuel pump is electronic. How do I know if it is a bad fuel pressure regulator and not a bad fuel pump?
 
I was taught to fix what you know for sure is bad first before opening too many cans. 26 psi is low and needs to be addressed first. A bad fuel pressure regulator will leak and cause high fuel trim readings, black smoke, rough running, etc. If you pull the hose off fuel pressure should increase if its working properly, if no change the pump has probably had it.
 
Pressure regulator is easy to change on these. One bolt and a rubber hose, at the end of the fuel rail. I replaced mine from a weeping fuel leak, but the result also ended up in faster starting. It was surprisingly expensive, $73 at the local AZ.
 
The pressure regulator is on the fuel pump assembly in the tank and not sold seperately so you are looking at a fuel pump assembly anyway. They aren't expensive last time I checked. Like ~$100 ish. Just a bit of a PITA to do in the driveway without a lift but it can be done. Run the tank to low fuel light before doing it, makes the tank easier to manage.
 
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Originally Posted by StevieC
The pressure regulator is on the fuel pump assembly in the tank and not sold seperately


No its not, it is on the rail as meep said on both the 2.5 and 4.0.
 
Originally Posted by Trav
Originally Posted by StevieC
The pressure regulator is on the fuel pump assembly in the tank and not sold seperately


No its not, it is on the rail as meep said on both the 2.5 and 4.0.

I don't believe you are correct. Not trying to start a war, but I just looked it up on RockAuto and they list it on the pump assembly. Unless they changed mid-cycle sort of thing. I know with my Caravan it in the tank and it was about the 2000's they switched them from the fuel rails to the tanks.

https://www.rockauto.com/en/catalog...r,fuel+pump+&+housing+assembly,10147

Pressure Regulator.png
 
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Originally Posted by StevieC

I don't believe you are correct. Not trying to start a war, but I just looked it up on RockAuto and they list it on the pump assembly.

https://www.rockauto.com/en/catalog...r,fuel+pump+&+housing+assembly,10147


You post too [censored] much. You don't have to have an opinion on everything, you know. Every thread I open up is littered with your posts, it seems like.

I'm pretty sure Trav has actually worked on these things. Speaking for myself personally, I'd go with that over "I looked it up on RockAuto..", but YMMV.
 
I have just as much right to post as Trav. Don't like it keep scrolling. Who made you the "police" ?
smirk2.gif


Also, I looked it up after Trav said something because I recall seeing a regulator in the fuel tank for this fuel pump assembly model.
 
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Originally Posted by Trav
Seems that is correct. The one I did was probably older than 98.

No problem. Chrysler has switched things before mid-cycle and from model to model when they encountered problems so most likely that is what happened.
 
Originally Posted by StevieC
Originally Posted by Trav
Seems that is correct. The one I did was probably older than 98.

No problem. Chrysler has switched things before mid-cycle and from model to model when they encountered problems so most likely that is what happened.


Looks like it changed for 1997, as the part shown for 1996 and earlier looks completely different.
 
I know they went to regulators in the tank largely around the 2000ish. The reason I remember this is because we had a car that would go severely negative fuel trims at idle and start running like a bag of bolts and fuel pressure was erratic at idle but fine at higher RPM's and when we looked up the service information for the vehicle it said it was a part of the fuel assembly in the tank and it was a PITA because the tank was full of fuel.
 
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Stopped at maintenance garage at the school where I work. I used their fuel pressure guage and the Jeep came from their fleet. Only 96k miles. It saw oil changes every 1000 miles. Oil was last changed in April and only has about 700 miles on it currently. But, I digress. They confirmed that the fuel pressure regulator is part of the fuel pump assembly. So, I will be ordering a new fuel pump.
 
The 2000 grand Cherokee we bought for a donor has a frame mounted regulator. First time I have seen that. The regulator rarely fails and when they do fuel pressure goes up. I'm betting on a bad pump.
 
Does the pressure come up if you cycle the key from off to run twice? My '98 XJ does this occasionally, but the double cycle always gets it running. Then it won't do it again for 3 months! I know it needs an FP, just trying to hold out for warmer weather to drop the tank & do it.
 
If your fuel pressure is down, then thats definitely an issue.

The IAC valve on our cars controls all the air at start up, if you can get the car started with pushing the gas pedal all you are doing is adding more air and removing restriction.

If you do not have any skid plates installed, the tank drops out really easily.

https://www.youtube.com/watch?v=5gm_m1hKtY8
 
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The XJ has issues with the fuel check valve, try priming the pump twice before startup like @bullwinkle suggested
 
Drove my 97 ZJ for many years and miles with the same issue. However, I just got used to priming the pump two or three times every time I went to start it and it never gave me struggles.
 
Originally Posted by Brons2
Originally Posted by StevieC

I don't believe you are correct. Not trying to start a war, but I just looked it up on RockAuto and they list it on the pump assembly.

https://www.rockauto.com/en/catalog...r,fuel+pump+&+housing+assembly,10147


You post too [censored] much. You don't have to have an opinion on everything, you know. Every thread I open up is littered with your posts, it seems like.

I'm pretty sure Trav has actually worked on these things. Speaking for myself personally, I'd go with that over "I looked it up on RockAuto..", but YMMV.


Originally Posted by Trav
Seems that is correct. The one I did was probably older than 98.

Lol, oops.



if-you-cant-say-something-nice-dont-say-nothing-at-30591467.png
 
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