BlueXJ

Try shorting across the ballast resistor inside the engine bay on the drivers wheel-well. If that helps you can really eliminate it. It was put in to make the fuel pump quieter. It lowers the running voltage to 9volts I think I recall. If that doesn't help then it is one or the other two remaining parts. Regulator or pump. Regulator is not too difficult to change but you will need one of those quick connect tools. Most parts stores have the ones for multiple sized lines for about $4-$6. everything else about the regulator is pretty self explanatory as you change it by removing a couple small bolts and the fuel line and off it comes.
The pump is a little more expensive and I would save it as last b/c you may solve it with these first two possibilities.

jpdocdave

haven't read this whole thread again, but if you got no fuel pressure on the rail. check for voltage at the pump at the connector at the tank. if you got power at the tank, and no pressure, pump is bad. if no power at pump, gotta find out why. fuses, relays, resistors, grounds, wiring.

theangler

Well I havn't tested, but i'm sure i'm getting power. I hear the pump prime and it will start, it's just hesitant and slow starting. Got a new fuel pump so that's going in today. Like I said, at 180k, it's a good idea anyways. But hopefully that's the only problem. If not i'll check regulator

theangler

So I put in a new fuel pump and now it wont start. I talked to a guy down at the local shop and he said to check and make sure that the positive and negative leads on the pump plug aren't mixed up. Since the plug isn't keyed I hope that's what it is. I'm going to try switching them later when I get out of work.

theangler

Turns out the guy was right. The pump's polarity was reversed so it was pumping backwards. Starts up and runs much better. Now I just have this damn part time 4x4 light that won't go out. gotta check if it's actually in 4x4 or just the light's on.

So it turns out that I did need a new fuel pump!

elementsquared

A

BlueXJ

Element there is more than just fuel involved. You need spark and air and compression. They all have to work at specific times (timing) are you sure everything else is working in concert?

theangler

A few days later, I wasn't getting spark either. New ignition coil set that straight! Now I've got correct fuel pressure and spark.

jesses89cherokee

what is the correct fuel pressure for the 89 xj? im havin the same issue. the p.o. told me the fuel pump was changerd recently. so idk. maybe tps? it runs fine at an idle. just hesitates from a stop to a few miles an hour. runs fine after that till i let off the gas stop and reapply gas... UGH! anyone wanna buy a jeep? they werent lying when they said just empty every pocket. thanks for the help.

jesses89cherokee

can anyone help me? have the same problem as angler. what pressure should i be having at the fuel rail? i had the tps checked and they said there was no flat spots. i hear fuel pump turn on. just want to know what normal pressure is. also thinking the map sensor or the coolant temp sensor? BLUEXJ said something bout shorting the ballast resistor... were is that n what will this eliminate as a problem? thank you in advance...