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1996 XJ Fuel Pressure/Pump Issue?

Leedog13

NAXJA Forum User
Location
Omaha, NE
I realize this is a common problem, but I've searched the threads and am not sure how to diagnose. I have to "prime" my XJ 2-3x to get her to start. I do hear the pump cycle each time, so I am pretty sure the pump works. Why then do I have to prime it? I assume it has something to do with the fuel pressure, when I relieve the pressure valve on the fuel rail before attempting to start, only a trickle of fuel comes out. So yes, probably a pressure issue.

This is a 96, one year only with all-in-one fuel pump, correct? So I need to replace the entire in-tank pump, correct? Can anyone tell me the exact replacement part, maybe a #, and preferred brand? How much would the pump cost?

Thanks everyone, appreciate your help!:us:
 
Welcome to the fun of the '96 fuel system.

Yes, it is unique to 1996, but no, you don't have to replace the entire assembly. In fact, you can replace the regulator only if you so choose. And yes, I realize a whole bunch of information out there says otherwise. I say it is wrong.

I have written it up here: http://www.naxja.org/forum/showthread.php?t=1107991&highlight=1996+fuel+pump

FWIW, my experience began exactly as yours. I had to prime the system several times each time I needed to start the Jeep. I put up with that for a while, but then the pump died entirely and that led to the above link.

Short answer is that the fuel pressure regulator for a '96 is the same as the previous H.O. years but provides a different regulated pressure because it is not hooked up to a vacuum line.

Hopefully this helps. Post up any questions or issues you run into.
 
Borrow a fuel pressure tester from Autozone and plug it into the rail, probably shows pressure drop very fast after engine is killed. There's a one-way check valve built into the pump that keeps the line pressurized after the car is turned off. The valve goes bad, and no longer holds pressure, so all the gas in the line drains back out whenever the pump is turned off, and you have to repeat every time you start.

If your jeep has two lines at the fuel rail, you can rig up an in-line check valve in the soft line between the tank and the filter. If it only has one line on the fuel rail, you shouldn't do that.

Either way, the real long-term fix is to replace the pump.

ps--Its possible that the FPR in the rail is leaking, but you can eliminate that by clamping the return line (the soft line that does not go into the filter), and if fuel still drains out then its a supply-side problem.
 
ps--Its possible that the FPR in the rail is leaking, but you can eliminate that by clamping the return line (the soft line that does not go into the filter), and if fuel still drains out then its a supply-side problem.

Just for the sake of the sanity of the OP and anyone else who may stumble across this while looking for a solution--there is no FPR (fuel pressure regulator) on the rail of a '96. The FPR is in the tank along with the pump/sending unit, and that is why there is no return line and therefore no option to simply add a check valve to the system. The '96 is like the '97 and later in that regard, but the tank is the same as '95 and earlier. It makes for an illegitimate step-child of a situation.
 
There may well be, but if someone with a '96 has an FPR on the rail I think they might as well just treat it as a '95. I don't think any of the other unique aspects of the fuel system would be likely to apply.

Mine has an April build date, so should be somewhere in the middle of the '96 production.
 
Everything I can find shows the same 39 PSI FPR for 91-96. I think the confusion about higher pressure is that the injector part number list that shows up everywhere says 49 PSI, however if you normalize to the "standard" 43.5 PSI that is most often used to identify flow rate, then the injectors are all the same 24lb flow rate. I can't find the PSI for the 97+ FPRs, but if stock 96 uses the 39 PSI FPR and the 97 injector flows at the same rate, then that tells us the 97 injector is probably plumbed for 39 PSI. What does the 96 FSM say pressure should be at the test port?
 
49 psi.

And that is what I am getting with the Crown 53030001 FPR.

CherokeeFuelPump51OPT.jpg
 
Anak is right. It's an early/late thing - BUT they went to the new fuel system when they went to OBD2, so 96 is this horrible bastard fuel system that uses a 95 down tank, 97 up fuel rail, one 95 down fuel line on the frame, 95 down fuel filter, and its own single-year fuel pump assembly that no one actually produces, so if yours rots out, you're kinda boned. Guess how I found out!

(as he noted, though, the pump, pickup sock, and regulator are available aftermarket, so as long as you don't need the sheetmetal mounting hangar/bulkhead piece or the level sender, you're fine.)
 
Thanks a lot for all of your answers, it's great info. But one last question, what should I buy if I'm going to replace the entire thing? Brand name/model number?

Appreciate it!!
 
Thanks a lot for all of your answers, it's great info. But one last question, what should I buy if I'm going to replace the entire thing? Brand name/model number?

Appreciate it!!

You don't. They don't exist, sadly. If you find one that claims it's for a 96, make sure it has the right (6 pin, 5 populated iirc) electrical connector and ONLY ONE fuel hose barb on it. If it has 3 pins and 2 barbs it's for a 91-95 or a 90 down and the manufacturer hasn't actually tried putting it in a 96 and assumed it would fit since the tank was the same.

If you find an actual OEM dropin replacement for a 96 that fits those specs, I'd absolutely love to hear about it, because I get this question a lot and I have no good answer for the poor bastards with rotten sending units.
 
Thanks a lot for all of your answers, it's great info. But one last question, what should I buy if I'm going to replace the entire thing? Brand name/model number?

Appreciate it!!

I don't know that anyone has a complete unit available. That is the challenge of a part that is unique to one year. There is not much money to be made producing and maintaining inventory on such an uncommon item.

As long as your fuel gauge registers properly and the top of the unit hasn't rusted out you are best off planning to rebuild what you have. The parts to do that are available.
 
I thought I'd found a complete unit on Amazon a
while back. Turned out it was for a Grand instead of
XJ. Had to send it back.

Lots of searching turned up nothing. Like everyone says,
it must be an unobtainable part.
 
I have found several on E-bay,,a while back. And by running a search in used parts(junk yards) on the web.Got one when a local parted out wrecked 96.
Had a good one slip by last week ,when I got two drivers side doors from it.Though about fuel pump ,but was too late,,,,,,,XJ was gone...
Try looking at local Jeep club members who part out damaged XJ,s.
 
I take it back, they are being made! Friend who works at Crown just happened to send me this on facebook, as I recall I suggested it as a product a while ago.

If you know of a Crown dealer local to you or online (jeep4x4center, quadratec, etc?) They should be able to get this. Wish this had been available in spring '09 when mine rotted apart.
http://www.crownautomotive.net/product/XJ-Fuel-Modules/5003869AA.html
 
That's good news.

Morris 4x4 carries Crown. That part does not come up on their site, but I would think they should be able to get it.
 
I tried to order that unit from the link, and a few days later I got an email notifying me of a refund with the explanation that their vender cannot get that part anymore. I also tried Quadratec, and am waiting to see if they can get it. My fuel level gauge has never worked, and my rail pressure test gauge will go up to 10 and immediately drop back down. Was hoping to get the whole assembly so I can have a working fuel gauge, but if Quadratec cannot come through, I may have to just get a pump and pressure regulator to get the XJ going and live without a working fuel gauge. We'll see.
 
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