DirtDaddy

90 XJ (Renix) Starts then immediately dies. I can hear the fuel pump kick on when I turn the key on, but not all the time...If I turn it on to prime the pump then turn it off and then back on, I will not here it pressure up on the subsequent turns on. What troubleshooting sequence makes the most sense? Any help appreciated!

Turbo X_J

How are you positive it is a fuel delivery problem, whats the fuel pressure in PSI?

xjeeper87

try turning the key on then off wait a few seconds then on again i had to do this with my 88 renix when it wasnt run for a few weeks.

DirtDaddy

I have not checked the fuel pressure yet...But it sounds like that should be the next step...I've driven it a few times now and it's pretty much every time now that it won't stay running, and then magically, I hear the fuel pump kick in after several tries and it fires right up and stays running.

jeepsurfer1

Me and parsnip had the exact same problem 1990 Jeep Cherokee it would fire then die, after aprox 1-5 seconds we replaced all 4 of his relays and he drove it home, I would give it a shot if nothing else you'll have spares and you could use them for other projects

freegdr

Try by passing ballast resistor yet ,also onces fuel pump primes it will not run again until fuels is needed ....

jeepsurfer1

also if you have a friend with the same are roughly the same model year being a remix era try swapping out there a PCM with yours its under the dash driver side what could it hurt lol

DirtDaddy

I was going to check the fuel pump relay this morning and then the PCM.

Jeepsurfer1, it's funny you should mention "a friend with a Similiar year XJ". My son is home from college and his 1990 2-door is parked right next to mine at the moment and I'm pretty sure I have rights to anything on his Jeep since I helped (meaning "paid for") with every mod on his Jeep...And he's still asleep. Shhhh...

tjwalker

This is the NEXT thing you need to try. Takes all of 5 minutes.

If the ballast resistor is faulty, the engine will run for a few seconds then die. Why? By design, the ballast resistor is "out of circuit" when the key is to the full right start position. That allows the pump to get a bit of fuel to the engine. But when you let off the key and it springs back to the "run position", the ballast resistor is now back in circuit and if it is bad, you get no fuel to the engine.

These resistors fail frequently. They can be replaced or bypassed permanently. They are there only to reduce noise on the fuel pump circuit. Later model XJs don't even have them.

Gotta rule it in or out.

cruiser54

Do this to the relays and move them all down a space, ending up with teh 4th relay in the 1st position after cleaning.

:
I suggest unplugging EVERY electrical connection in the engine bay you can find, whether engine related or not, and spraying it out with a good electronics cleaner, visually inspecting the terminals making sure they haven’t retracted into the plastic holder, and then plugging it back together. There’s a critical 10-pin connector for the front lighting system located in front of the air cleaner and behind the left headlight assembly. Don’t miss that one. Also be sure that the connectors to the ballast resistor mounted near the air cleaner housing are clean and tight.
ALL of the relays should be removed, the terminals wire-brushed until shiny, and the receptacles sprayed out with contact cleaner. Then plug them back in. I do this on every Renix Jeep I purchase or work on for someone else.
Revised 07/23/2012

cruiser54

Then take a look at the ballast resistor connections as described in the above write-up. Here's a pic.

jeepsurfer1

it's easy to get to just take out the driver side of the lower dash and take the connectors out I think the whole process is 3 screws and 1 or 2 bolts, and junk yard 40 bucks for the CPU Advance it's 99 + a core but I would definitely check the relays thoroughly and check the ceramic ballast resistor let us know your findings

justin92xj

I had the same problem. Bypassed the ballast resistor and no more problem.

DirtDaddy

Refreshed every connection I could find under the hood...Haven't had any problem since! Thanks for your help everyone!

jeepsurfer1

Woot