bvfd920

New to the site as of a few minutes ago. Bought a '93 Cherokee in May and will begin building it up eventually. Right now it is my weekend ride to go to the shooting range. Anyway, anyone know how to diagnose a possible fuel pump failure? Getting some hard starts, not the battery though, and then some rough running initially after start, and then some surging when exiting the highway and dropping back to slower speeds. Put battery on tester and it tested a little higher than the rating. Fuel filter was changed before i got it in May. Transmission fluid and filter changed also before i got it.

Jeep is just running a bit funny, so not sure how to diagnose the problem yet. This is my first 4wd jeep, had an 01 xj, and 2 - 04 grand cherokees in the past but those 3 were 2wd. 4wd seems to operate fine, transmission seems fine as well, but could the surges at slow speeds be tranny related? Will have to drive it this weekend and see if it does anything funny again.

Anyway, seems like a lot of posts on here, so i will go explore for now....

BuckB91XJ

A FP problem is farely easy to diagnose on an XJ. There is a small cap on the fuel injection rail. Remove that cap and there is a threaded fitting under it. You will need a hand held pressure gauge to attach to this fitting. start your Jeep up and you should have 30 +- 2 PSI anything more or less than this and you have problems. Litterally anything less than 30 and you will have missing and hard starting. If this is your case then you will need to replace the fuel pump. Now, if you have 30 PSI at this point, remove the vacuum line from the Fuel Pressure regulator at the front end of the fuel rail. The reading on your gauge should jump up to 39 PSI with this vacuum line removed. Of course if this reading is wrong then you have a bad Fuel Pressure Regulator. i hope this helps you out in your troubleshooting.

bvfd920

Awesome! I knew someone on here could point me in the right direction! I will try to check that out this weekend. Never was much of a mechanic, but bought this as our 3rd vehicle in the household, so if it is broke in the driveway, it won't be keeping us from getting to work. This is going to be my little project for the next few years. Lift kit, tires, and possibly some OrFab bumpers and a winch in the near future.

Thanks for the advice, and I will be back on here if the fuel pump is not the issue to search for more advice.