Detail: 1989 jeep wrangler 2.5 f.i. sometimes it starts and runs great. most of the time it doesnt start. Its only getting around 6 volts to the fuel pump, and the relay. could there be a short? Tried running it off a switch, that doesnt work. the ignition switch in the column was also changed.
Solution: If the 6 volts is not steady it can be the earthing, or a bad connection on the relay. if the relay is getting hot then replace this as this can be a problem when the relay is warn. clean all the earthing points and wires. this will improve the the electric flow. also if you don't have one fit a ***** strip wire from the body shell to the engine, this can improve alternator voltage, meaning better charge to the battery. , Hi, a 6ya Mechanic can help you resolve that issue over the phone in a minute or two. Best thing about this new service is that you are never placed on hold and get to talk to real repair professionals here in the US. click here to Talk to a Mechanic (only for users in the US for now) and get all the help you need. Goodluck! , check your fuel pump relay and your ignition switch those numbers you gave for voltage are not right, please recheck that you have a ground and 12volts at the pump while cranking please rate -jeff , Had similar problem with 96 Jeep 4.0L engine. Tracked it down to the connector for the distributor pickup. Spliced in another connector and hasn't stalled since. Also, have you had any codes? Easy way to check on Chrysler products: turn key on, off, on, off, on (not starting) and watch the 'engine light' on the dash. It will flash off/on. Count the flashes with short pauses between and longer pauses between code. When you get a 5 count and 5 count, that is the end. This may also help , crank sensor likely-may be distributor sensor but my 98 sport was crank sensor situated in bell housing timed by flywheel , sounds alot the the pcm it controls the fuel pump and ign system but the anti theft would keep it from starting because the key has a transponder in it programmed for that vehicle and that would kill all ign if triggered , Two items that fail most frequently are the fuel pump (which you replaced) and the crank position sensor (11 o'clock on the bellhousing looking from the rear) That can also give you similar symptoms. Problem is it may give you good readings if you test it while it's working correctly. It's a pain to install and isn't very cheap so, I suggest you get a haynes or chilton manual and a digital multi-meter and follow test procedures before buying anything further. Could be that or just a loose wire somewhere. You can also get a code test done free at most major parts outlets. Won't hurt to have that checked as well!! Good luck...any questions about specific parts etc, just ask!!