laytox

2001 XJ (155k miles) here, been battling this for months now. Issue started when I got my battery and negative battery cable replaced. Would have to keep the key turned for several seconds before it would fire up. Took it to the shop, they said starter, replaced starter. After that it would only start after multiple cranks. Shop said fuel pump and fuel pressure regulator. They over quoted me on the regulator so I told them to do the pump and I'd do the regulator later. They change the pump, nothing's fixed. I ran out of time and had to move cross country. Replaced regulator after moving, still didn't help. Replaced all 6 injectors (they were old and cracked, needed to be done anyway, went with 4 hole Bosch just because). Today I even replaced the fuel pump relay in a last ditch effort, no luck.

I noticed no pressure on the fuel rail when changing the regulator (no surprise) but when I did the injectors yesterday I again noticed no pressure (don't have a gauge but no fuel came out when I pressed the valve). Only CEL codes are for catalyst inefficiency. Shop said there's a possibility that my PCM needs to be replaced. I'm losing my mind trying to figure this out. Have had battery tested, positive battery cable terminal replaced. Only other thought is maybe the new pump got fried after driving around with no pressure regulator? Any and all help is appreciated, I'm a novice but at this point I'm done taking it to the shop and want to take care of any repairs myself.

jordan96xj

Focus on the fuel pressure problem first. Get a fuel pressure gauge if you can. A fuel pump/pressure issue on your Jeep will not have anything to do with the PCM. The chances of it being the culprit are very slim considering you already know that you have a fuel pressure problem (or at least it looks that way, until you know for sure with a gauge).

laytox

Rented a fuel diagnostic kit. With car off pressure drops to 10psi then slowly to 0-5psi. When I turn key to on without cranking, pressure goes up 2-3psi then drops back down. When I crank, pressure goes up to 20psi, jumps up to 50psi but still won't turn. Next time i turn the key to on, pressure jumps to 45-50psi and it cranks right up and pressure stays constant.

I'll hold on to this kit for a couple days just in case. Is that adequate information or is there something else I should test?

jordan96xj

With key on, engine off, the fuel pressure should come up to 45-50 and remain for some time. Even if it leaks down quickly, it should be enough to start the vehicle in the next few moments after turning the key on.

The symptoms you post sound suspiciously like a failed fuel pump check valve, regulator, or both. If the pump itself were failed, I think you would never get the constant pressure after the motor was running.

Here is a video from "Pine Hollow Auto Diagnostics (Ivan)" that starts with the same symptoms, and ends with the same conclusion.

What was the brand of fuel pump you put in?

BlueRidgeMark

Obviously, you need a new shop, or learn to do it yourself. Sounds like you are on the way to learning to do it yourself, so that's good.

You have the info you need on the pressure - your numbers are not good. Now the question is, "why not?".

You have a pump that was put in by a flaky shop. They may have simply scammed you and not put in a new pump at all, or they may have put in a junk pump. Bosch is about the only good pump out there for your Cherokee. You might want to do some detective work to see if they even changed it. Look at the J-bolts that hold up the tank - they will tell you if they have been moved lately. It's not uncommon to have to replace them because they are rusted too badly to remove without cutting. I'd say take a look there first (it's free) to see if they even touched it.

laytox

The paperwork does not provide details on what pump they used, but judging by what they billed me it damn well have better been the best pump on the market. I was wondering myself if they even did anything because there was literally no difference in starting after they "Replaced" it. I'd prefer to rule out everything else before throwing another pump at it (doing the regulator by myself was a PITA). When pulling the tank for the regulator it seemed as though the connections involved had been worked on recently, but that doesn't rule out them putting in a bum pump.

Would it be worth it to go ahead and rent a diagnostic reader to help figure this mess out?

Worst part is, I've been to 3 different shops, all of which have suggested to just throw parts at it like I'm professor freaking moneybags

laytox

Also I'm curious - does a new fuel pump assembly come with a fuel pressure regulator or do they come separate? All the pictures I see show one attached... pisses me off even more if they were trying to charge me separately for a part that they already installed.

CurrySoSpicy

It's not uncommon for unscrupulous shops to charge OEM part prices then use the biggest POS part they can find. And yes "firing" the parts cannon is no good. Wasted time, money, energy.

A code reader would be advisable, however it probably won't help you out with fuel related issues. As the XJ has no supervisory circuitry monitoring the fuel delivery system.

laytox

So turns out the parts and labor were covered under a napa warranty, so took it to different napa-certified shop in my new town and after a new round of diagnostics they're not convinced the new pump has failed... any other ideas of what the issue could be?

CurrySoSpicy

I don't know man, I'm the fuel delivery system has a few components. If you don't have any pressure or can't maintain pressure something is wrong with the delivery system. Be it the pump, filter, giant gaping hole blowing fuel onto the undercarriage (sarcasm alert). What "diagnostics" did they perform?

laytox

They didn't say specifically but I'm assuming the same fuel pressure test I did... They did mention a cylinder 1 misfire and I realized that at some point someone removed the heat shielding from the injectors, but would heat soak cause a pressure issue? I feel like it would just be performance

CurrySoSpicy

No, I would doubt it. My 2001 had heatsoak issues until I remedied them. But it still started after a heat soak condition, just rumbled a bit from the misfire.

So the shop had fuel pressure on the rail then? And everything is fine with the fuel delivery system in their opinion? Just don't get how we have two significantly different conclusions from the same experiment. The scientific method would say the variables are different. In other words, one of you is wrong.

laytox

I know right? Wondering if these guys are trying to get out of having to fulfill the warranty... starting to distrust all mechanics at this point, but I still don't want to dish out money on another new fuel pump if they'll replace it for free

CurrySoSpicy

Maybe call them and get the details of their diag. Good luck man.

s346k

this is hard to follow. what i'm getting from this is the check valve is bad in the fuel pump and you must poor man prime it to start. which means cycling the key 2-3 times before starting, after this is done it fires up and runs fine. am i reading this correctly?