OK... long time lurker, first time poster.
Edit: I guess I did post my Intro back in 2014.

Here's the scoop. I have a 1991 XJ 4.0 that I've had since I bought it new in 1991. It's older than my marriage.

Anyway... the starter was starting to go, so I installed a new one. She was running fine before the starter swap. Once I swapped the starter... she'll crank, start for a few seconds with a very low idle, then stall. Giving it any gas causes an immediate stall, or gassing it to start causes it to not start.

What I've done so far:

• Replaced the battery the day before replacing the starter
• Checked battery connections several times
• Removed negative terminal a few times to hopefully "reset" things
• Battery is on a trickle charge while I diagnose and go through several start cycles. Battery is at 100%
• Checked all fuses and relays
• Checked ground connections
• Replaced the fuel filter
• Rechecked connections to starter
• Found a hose (looks like a vacuum line of some sort) right next to the starter that was off... I must have knocked it off while replacing the starter. I re-attached it, but symptoms are the same. (Anyone know what that hose is for?)
• Replaced IAC
• Checked throttle body... she's clean
• No restricted airflow from easy to check sources

I'm sure I can start throwing sensors at it... but what baffles me is that it was starting and running fine before I changed the starter, and now... all of a sudden it's doing this:


The two things are probably not related (new starter = new symptoms) so it may be a coincidental issue that I need to track down. So, if anyone has any ideas... please throw them out, I'd appreciate it. I wrench on it myself, and most things are pretty easy to diagnose on the XJ, but this one is frustrating the heck out of me.

Thanks again guys,

Bob

 

Clean the grounds at the dip stick tube,
clean the ground at the battery,
Also make sure you have good connections at the starter relay on the fender.

 

Thanks for the quick response Caish, went back out to the garage:

• Cleaned the ground near the dipstick tube
• Removed and cleaned battery ground
• Removed the starter relay and replaced it with a working relay... no change. I did this before as stated in my OP, but I thought I'd give it another shot since you mentioned it.

Symptoms are the same.

 

Found and acknowledged your "easter egg" in the other post.

Have you checked for vacuum leaks? Need to unhook one at a time from the manifold and block it off. If things change then you know what system is affected and where to go from there.

 

To me, that completely sounds like lack of fuel. Whether caused by injectors not firing, insufficient fuel pressure or whatever.....

The quick and easy test/check, suggest dribbling some fuel from a container into the intake while attempting to start?

 

FIXED!

It was indeed the fuel pump. It was apparently a coincidence that it stopped working immediately after I replaced the starter.

Well... after checking all vacuum lines, relays, and electrical connections... I finally decided to go the extra step and just replace the fuel pump. I figured that the worst case scenario would be that I'm out $80... but at least I'll know that I have a new fuel pump.




View from the bottom... Glad I put that lift on this Jeep a few years ago, otherwise it would be really tight down here.




New Fuel Pump



Hardest part of this job is removing that retaining ring!




26 years of crud in that fuel strainer.



Other view of the fuel strainer.



I think this was my main problem. The main fuel line appears to have become disconnected inside the tank. It certainly would make sense for it to "all of a sudden" not work anymore, especially when I could hear the pump working. Although... it could have happened when I removed the pump from the tank. I'll never know... but I do know that this old pump is never going back in.



New Fuel Pump in. Just need to hook up lines and electrical. 2nd hardest part about this job... re-installing that retaining ring!

 

Hazzah!

Starts quickly... quicker than before. Idles great too... tons of fuel pressure as well. Fuel shoots halfway across the engine bay from the fuel rail now, instead of just dribbling out.