boydballer92

I just bought an 87 XJ and it will turn over but it wont start.... The guy I bought it from replaced the fuel pump and got it running for 5 mins then it shut off by its self... he said it was either the cam shaft sensor or a "coil"... and I have talked to a few friends who own XJs and they all say its most likely the fuel filter is bad.... I'm gonna go to autozone on tuesday and get a new batterey and fuel filter but before I go I would like to know what you guys think is wrong since you guys are pretty reliable with your information...
thanks

90waxj

I would check your fuel pump resistor, it sits on the inner fender right next to your airbox. Check the wires and also the contacts, when mine started doing this i went right to the resistor and cleaned it and never happened again. All this does is control your voltage going to your pump during start up and running loads. Might as well start cheap and easy before diving in a spending tons of money for nothing. Hope this works for ya

boydballer92

yea I'll check it out tomorrow when i get it hauled up to the shop( open parking lot at my grandmas house with an easy up).... if it is that though that would be a life saver... cuz its ready to hit the trails and I wanna get it into town where I have an actual shop to work on it at... But thanks for the help.. Brand new to auto mechanics so i'm not too sure about most of this

90waxj

Well you found the right place to ask your questions. I would just buy a new one instead of checking it now that i think about it....its only a 8 dollar part at Napa or depending on where you live, it may look fine but still could be failing. Also im sure you have heard the buzz about Seafoam, i would pick a can of this up as well and run it through your system. If you plan on wheeling and drinving long distances this will make a huge difference on MPG and also performance. Also when you say he replaced the fuel pump and it started up for like 5 minutes and cut out, did he replace the fuel filter as well? This could also be the problem and a very easy fix. Replaceing the fuel pump and filter should be done at the same time to avoid any particals to get kicked up into the system. If it was the coil the guy would nver had got it started and the cam sensor would have made on hell of a missfire and you would know what that sounds like. And the battery would only effect start up , you can actually disconnect the battery while the vehicle is running and it would stay running until the key gets turned off, thats what the alternator is for so save your money on that and try the other stuff. Hope all goes well

bishop letov

I just did the pump in mine and fuel filter.. had to replace it after two days because the purilator filter broke apart on the inside and charcoal or rubber was getting to my fuel rail. never ever had a filter do that to me before.. it rattled when I took it back down and black crap came out both ends..

if it was the fuel filter then you would get a couple of mintues or longer till it clogged itself back up . Usually youll be pressing on the gas and itll seem to bog with higher demands unless theres a ton of crud. I know advance has a policy about replacing the sock on the pump when you buy a pump so that it limits the amount of bottom of the tank crud that enters the fuel line.

Im gonna second the fuel pump resistor and or the fuel pump relay. When they heat up they stay made or closed to allow contact. once the relay coil cools again it will do the same thing. Ive heard of the resistor being bypassed to see if thats the culprit but just for testing. If its found to be faulty replace it and dont just leave it out.

Check your fuel pressure its one of the best ways to diagnose the fuel system without crawling under the jeep or taking down the tank to check if the pump was installed right.