No Start XJ

87 4.0 AX-15 Renix

It will crank, turn over but not fire. It seems when the battery is at full charge it starts up fine, although I'm not convinced the battery is the problem. I've changed the CPS, so thats not it. I changed the spark plugs and checked for spark, and that was good, so I figured fuel issues. I also checked the distributor and the cap and rotor looked great, cleaned it out nonetheless, along with cleaning all my connectors and relays with some canned air and dielectric grease. I changed the fuel filter and it seemed to be fine for about 10 minutes of running perfectly, only to die while driving, and not starting back up. I thought it might be the ballast resistor issue that is common, so I jumpered the two wires and nothing changed. I'm convinced I have a bad fuel pump because, as far as I'm aware, its never been changed out, although it could be my coil, which I haven't checked yet.

ALSO, I'm pretty sure I have a short somewhere because I have to charge my battery everytime I work on my XJ, because after I let it sit for a few days and try to start it up, the battery is completely dead.

What do you guys think? I need to get this heep runnin' again!

TIA,
Kev

Best bet is to TEST your way to a solution; please don't throw parts at it.

Job #1 is to fix your electrical/battery issue. Your engine doesn't like it when available battery voltage is low. Resolve this before doing anything else. Get your battery load tested or temporarily swap in a known good battery as you try to resolve this. You really don't want to be chasing your tail chasing ghosts when your problem(s) have a battery component to them. I've seen a situation where the battery is charged enough to spin the engine over, but not strong enough to start the engine. Freshen all engine grounds while you're under the hood as well. Renix vintage rigs are very susceptible to connection/ground problems.

Try spraying some starting fluid into the intake. If it starts and runs momentarily, you have a fuel delivery problem, not an ignition (spark) problem. Fuel pressure testing at the fuel rail would provide some additional data for you if it's a fuel problem.

How did you check for spark? Need to ensure that you have a strong blue snapping spark. Orange/yellow is a weak spark; no good.

Good luck and post back what you find!

From your post sounds like you have confirmed spark.

Check for fuel pressure at the rail ,the next time it quits and/or won't sart.

My money is on a bad fuel pump or connection.

Good Luck

Nick

Where can I test fuel pump voltage? And what is the correct voltage, I've seen 11-12 volts. Also, fuel PSI should be around 39, right?