I hate to bother you guys and gals, but I have a problem with my wifes jeep and could use some help. As I am laid off I have a limited amount of funds to deal with and I am trying to avoid going to a garage. It has kinda started hard for the last year but has always kicked over. Today I get call from her she died at the oldest boys school from what she described she was out of gas, not the first time :rolleyes: I drove down with a 2 gal. tank and poured it in and it fired up. Tried to pull out and it died again. As it was on a hill I figured that there was not enough gas. I got 5 gal more and dumped it in. It started and I attemted to drive it home. It ran like crap, had to goose the gas to get it to go. Limped home and tried to figure out what was going on. Since it was ran dry for a second time I thougt mabey it was the fuel filter. I changed it out, it was in dire need of it, Started it up and same as before. It would run at 2K ok, in park, But left idle it would bog down and eventialy die. It is a 89 Cherokee Laredo with a 4.0 Strait 6 just so you know. It has a test port at the frony end of fuel feed to the injectors. I know it supposed to be pressurized system but when I depress it all I get is air. While it is running I get a burst of air and then fuel. My gut tells me I have a bad fuel pump. I also think the tank is full of crap. I am just wondering if you folks have ant inpunt as to wether or not I'm on the right track or not. I think I need a new fuel pump and also need to flush the tank. Any help would greatly appreciated. Thanks in advance. If I don't respond to questions right away, I am sorr, Trying to get the boys to sleep :D

I had exactly the same symptoms in my 89 a few months ago. Mine was opposite though...too much gas. Check out your MAP sensor and the vacuum line running into it. Mine had melted shut on the manifold and caused it to screw up the air/fuel mixture. If that tests good, my next bet would be a puking fuel pump. Does it backfire at all on you? When my fuel pump went south, it would pop and sputter every time I hit the gas. Something to check. Also, check your fuel pressure regulator. Those have a tendancy to quit for no reason and also produce the same symptoms. Good luck, I chased this stupid problem all up and down the engine bay before I finally found that burnt vacuum line.

Josh, I did check the vacuum lines, but sounds like I need to look a little closer. Yes it does backfire a little. Not too much though. The reason I can work on million dollar machines and robots but I kind of auto-illeterate. Go figure :rolleyes: From my experience with pumps if they cavitate or have bad seals they suck air. I am concerned that the pressurized fuel system has air when I depress the bleed-off. It only spurts gas when it is runnig, after a burst of air. Is it a good bet that my pump puked on me?

Hey guys I gotta bail, I got 2 boys that want to go to sleep and I gotta help the wife. It's either that or get second vasectomy. :rolleyes: :D I'll check back in the morning. Thanks again for all the help.

Crank position sensor ?

Originally posted by Mo
Crank position sensor ?

I doubt that. The CPS usually tends to be an on or off type of deal. Either the XJ dies and won't start, or it works fine. I had a few intermittent problems with mine before it went, but his fuel pressue relief spewing air seems to rule out the CPS. You never know though, XJs are kinda funny like that.

Try pulling the CPS wiring harness apart and cleaning the contacts to see if that does anything. I doubt it, but you never know.

Possibly a clogged fuel filter or fuel line?

Fuel pump going south?

my .02

Thanks Josh and Mo I'll give that a try, If that does not work I'm probably off to the U-pull it. Few weeks ago they had a cherokee identicle to mine I'll try a pump from there before I have to cough up the big bucks for a new one. Thanks again, I'll keep you posted.

Hey Boston, changed out the filter last night. Still have problems. :( From what I've searched and read and what you guys are saying, it looks like the next best bet is the fuel pump or the fuel regulator. Been kinda hard for a while, like the pressure was bleeding off the system. But I also got air in the system. I'll keep plugging at it. Thanks for the help guys. :)

I think you're on the right track. Sounds like a fuel pump or clogged pick up. I would drop the tank and see what's in it.