Hi everyone! Just bought my first Jeep, 1989 Cherokee 4.0L auto, came with an issue that I'm pretty sure is fuel-related, just wanted to see if the experts had anything else to check out before I get too far down the rabbit hole.

Issue is: starts fine cold, drives smooth, no issues. Once you get it warm, turn it off and try to start it again, it will crank, rev up into the 2k range for a second, then drop down towards 1k and splutter around for a few seconds before dying. It will also cut out and die any time you floor it.

Seller said he thought it was the fuel pump, which sounds right to me. It's been sitting a couple years, so the fuel system could be plenty gunked up. My plan was to replace the fuel pump and filter and see how that goes, but I've seen a few other suggestions like crank position sensor, etc.

Any thought would be greatly appreciated! Thanks!

 

go to www.cruiser54.com and do tips 1,3,4, and 5 before anything else.

 

Got 1, 4, and some of 3 done this weekend. It's been starting pretty reliably, but I haven't gotten a good long drive in yet to get it nice and warm, when the issue really raises its head. Friends were all too "busy" to be on call for a potential rescue tow...

The website has been a great reference so far, thanks for all the work cruiser!

 

Don't buy a new pump until you have done a fuel pressure test.

 

Yup, borrowed a fuel pump diagnostic kit from Autozone, just didn't get to checking it last weekend. Got distracted fixing a bunch of other little things and lost track of time. Hopefully this weekend!

 

Stay after the Tips.

 

Welp, got the fuel pressure gauge on there yesterday and got some weird results. Regulator vacuum line disconnected and it would wobble in the 28-32 psi range, once the line is connected, it shows a solid 30. Pressure would jump to about 38 once I shut it off. That's got me thinking kinked return line or something along those lines.

 

Pressure is low. Use only Bosch replacement pumps.

 

Ok, gotcha. Thanks for that, it's been a little frustrating trying to research what the problem is once you know there is a problem. Everyone says the fuel pressure should be 31/39, but not what might be wrong if it isn't that. Anyways, I got the Precision brand one from O'Reilly's that says "with Bosch OE pump" so hopefully that's legit. I'll get that installed when I have a chance, but I have a 2 week work trip coming up so that might be a while

 

Good plan. verify the pump is Bosch. Replace the fuel filter also.

 

Yup, will do. Bought that too when I got the pump, along with a siphon pump and a brass punch so hopefully I'm all set.

 

Pump and filter swapped out and she's running great so far. The filter that was on there was a way smaller diameter than the bracket for it, so I wonder if that may have had something to do with the issue. Unfortunately did the pump first, so I didn't get to test that theory, but whatever, at least we're running well now. Thanks for the help guys!

 

Excellent!!!!

 

Glad I could help!

Oh, sorry. Cruiser54 gets the cookie. Dang. I'm a day late and a dollar short. Story of my life.

 

Oh just you wait, there should be plenty more to deal with on this jeep. You wanna teach me how to replace a window motor?