96 XJ Fuel pump problems

[monkeywrench045]

I have a 96 XJ 4.0l with the dumb 96 fuel system. A while back I replaced the fuel pump after I was having problems with it sputtering when I would apply more than half throttle, the new fuel pump fixed that problem. Recently I was out driving and it worked fine for a couple of hours of offroading, then I turned it off and went to turn it back on a couple of hours later and I got crank no start, I cycled the fuel pump a couple times (off-accpwr-off-accpwr) and it started but then the sputtering occurred when I floored it or got into a little bit of mud. The next day I had to cycle the pump again to get it to start and as I was making a turn at 5mph it shut off. From what I've read, it sounds like a bad check valve, but I can't find a replacement for the check valve that goes with the in-tank pump assembly, and I am weary of putting an inline check valve in. Do I have to replace the whole fuel pump assembly and if so can someone send a link for one that's not too expensive (woods beater). Thanks in advance.

 

[Anak]

... it started but then the sputtering occurred when I floored it or got into a little bit of mud.

That does not sound like a check valve to me.

I would wonder what fuel pressure is doing or what your Throttle Position Sensor is reading at the point you floor it.

Have you cleaned your IAC lately? That doesn't cost anything (or not much--if you need to buy some cleaner) to take care of.

Given that use of the throttle helps to get it started I would put a scan tool on it and check the readings for the TPS.

 

[monkeywrench045]

Forgot to mention I replaced the tps when I replaced the fuel pump, I will definitely have a look and probably clean my IAC, thanks

 

[Anak]

Do you still have the old TPS?

I would be inclined to swap them and see if that makes a difference.

New parts are not necessarily good parts. Sadly.

 

[XJ_ranger]

Check fuel pressure at the rail as the first step in diagnosis for a suspected fuel pump problem.

 

[monkeywrench045]

Do you still have the old TPS?

I would be inclined to swap them and see if that makes a difference.

New parts are not necessarily good parts. Sadly.

I don't have the old tps

 

[Marcass]

Cleaning your IAC will give you instant, but short-lived results depending on your specific case. How open is your exhaust? I ran catless on my 00 XJ and had to clean the IAC every weekend. You might as well clean the entire throttle body while you have the tools out and working on that component. You have many contributions to the "weak" fuel system you are experiencing. Check pressure at rail. You will find the schrader valve on the driver side relatively close to the front. (just behind pressure regulator)

My 89 MJ eats fuel pumps like the Cookie Monster.

 

[Wayne Sihler]

Dont look for the fuel pressure regulator anywhere on the fuel rail.It,s in the tank on the pump assembly.Not all XJs have the same fuel system.

 

[THE2NDXJ]

As Anak mentioned, new parts are not always good parts. This is holding true more-so everyday. The amount of crap that China is spewing out is enormous. XJ fuel pumps are a crapshoot, and there are LOTS of XJ owners like myself who have gone through lots of trouble getting ahold of a good one. I went through it recently with one of my '01s, and the third pump has been working fine for a few months now. The first two only lasted about a month before the engine started dying out again. There are a lot of factors in the fuel system, but dont be too quick to rule out any new parts that you've applied.

 

[Unclewolverine]

I've had 2 tps bad out of the box.