91 XJ Starts then dies

Ok, I know this is my first post here but it won't be the last.

I just bought a 1991 XJ Sport with an AW4 and 4.0 The guy I bought it from said that he was out trail riding and the rpms just started dropping then it died and hasn't ran since. Replaced the fuel filter and it was trashed. With the line off of the filter we turned the key on and fuel came out of the line. Hooked everything back up and nothing. It will run off of starting fluid. Then after this we swapped in a fully charged optima yellow top and got somewhere. It will start up and run for about 5 seconds then sputter out and die. If I try to give it any fuel it will die. The tach is reading rpm while starting as well as running.

I inspected the fuel lines in the engine bay as well as under it. Everthing is fine, no leaks or crimps/pinches. I pushed in the schrader on the fuel rail and I can hear it gurgle back but it doesn't spray. Thinking it may need a fuel pump but I have read through about 40 pages of this tech section and it could be either the pump or the ckp sensor from what I have been reading.

Any ideas?

check crank position sensor??? fuel regulator??

If it runs off starting fluid, then you have confirmed a fuel delivery problem. Your problem is NOT crank sensor related.

The fact that you don't have solid pressure at the schrader valve indicates this as well. And ditto for the previous owners symptoms of RPMS dropping and the engine dying.

Most likely suspect is the fuel pump itself. A quick test with a fuel pressure gauge on that valve would confirm. If it isn't getting up to spec fuel pressure, it's not going to start.

Yeah, and I have gotten it to start and run for a few seconds and then it just dies off. I will be bringing my fuel psi gauge home from work today to do a few more tests. Then I have to try and get the tank out of this thing lol

Tested the fuel psi and it only had a few psi then it dropped off completely. I am going to replace the fuel pump and see what happens.

so anything change with the new fuel pump?

The fuel pump will be in today. It was 19 degrees outside last night so I didn't worry about pulling the old one out lol May have to wait till this weekend.

Should I replace the fuel psi regulator at the same time?

Go for it, no sense having to replace it next and ending up dropping the tank twice. Also check the strainer on the input of the fuel pump and make sure you clean all the sludge, water, mud, and random crap out of the bottom of the tank.

EDIT: I didn't notice you have a 91, your regulator is on the fuel rail at the engine, disregard previous advice, replace it if/when you need to

Yeah, I am going to take the tank to work and clean it out really well. Then put some fresh gas in it.

I was beginning to worry, I knew I thought I saw a regulator up on the rail lol

You are definitely doing it right by dropping the tank to replace the fuel pump.

I tried to change the fuel pump on my '91 with the tank on the Jeep and got nothing but frustrated...

Good luck.

Well. Found the problem. The fuel line on the pump assembly had deteriorated to the point that it was spraying fuel. I am going to get some fuel line and replace the line tomorrow.

I replaced the line and pump seal on the tank. Primed the system and it starts right up now. I borrowed a set of wheels and tires and played around with the new toy a bit.

Thanks for the help! I have learned quite a few tricks about the XJ! Now that it is running I have found the other things that need to be replaced such as suspension bushings, links etc.