My stock 98 xj 200k+ miles was cutting off while stopped and had some trouble starting, very sporadically. Recently, after driving to a camping spot 15 min from home, she gave up all together and refused to start, had to tow her home. After sitting in the garage for a while, it starts up, idles low, and turns off after 20 seconds or less, fewer if I put it into gear.

Recent work before issues - motor mounts, transmission mounts (was shifting hard in reverse, better after mounts were changed), oil change, oil pressure sending unit changed

Gauges - rpm doesn't move when it cranks with no start, check engine light on when it does start.

Thoughts?

 

Pull the error codes.

There's 3 things that could go wrong-- fuel, spark and/or compression. Measure fuel pressure, check for spark (spark tester, ground out a plug, hang onto the wire when cranking, etc.) and measure compression.

Check all 3 and report back.

 

Alternatively, wait for more suggestions and start arbitrarily shooting the Parts Cannon-- CPS, fuel pump, shocks, radio, ski rack, etc.

Eventually the Parts Cannon will hit the target, but is frequently expensive and you end up with a lot a spare parts you need to sell on eBay.

 

I agree with Ddave. Pulling codes with a code reader or a scan tool is absolutely job #1. Job #2 is to post the EXACT code(s) here for comment. Not just a description.

With OBD, the devil is definitely in the details.

 

I agree, check the codes first. Difficulty starting and cutting out sounds like the typical crank sensor failure mode, especially if you don't have any codes showing up. Have a good look at the wiring between the firewall and the exhaust manifold and make sure the wiring from the crank sensor and O2 sensor isn't touching.

 

No error codes are coming up

 

See if you get a 5.0 DC volt signal from the CPS (gray wire) with key on, coil disconnected and turning engine over by hand.

If you do check the camshaft position sensor same way while you got your stuff out (although that should have thrown a 1391 code)(but testing is free so why not).

 

You can also test during cranking but you'll get a value <5.0 volts (because the DVM is slow to react)(unless you have a DVA).