So my XJ has been driving me crazy lately. It is being very difficult to start like I mean at least 5-6 attempts no matter if it's hot or cold, but once started, it sometimes runs fine and sometimes very rough and not on all cylinders.

I have replaced the cps, coil packs, cam position sensor, tps, all other sensors on throttle body, ECU, and coolant temp sensor. Nothing has seemed to do any good and I am completely stumped. Any ideas?

 

Fuel pump starting to stick? Gas cap not sealed or hairline crack in fuel line/rail (wild guess, might cause fuel to siphon from lines back into tank?)?

These are far fetched, but it sounds like you've done most electrical checks.

 

It could be as simple as the check valve in the pump dying.

 

check for leaking fuel injectors.

 

How do you do this?

And I know that I'm getting fuel to the rail because I've checked pressure and bleed down rate with a gauge so I'm confident it's not the pump

 

Any. Heck engine light? Mine ran perfect til I had the battery disconnected for a couple days. Then it only had hard start and rough running sometimes. Eventually it started to do it all the time. Noticed my battery cables were loose at the clamps. Fixed that but still have the problem. Check engine light not coming on. Going to try cleaning the grounds that are bolted just under the coil next.

 

I do have a check engine light but the codes are for all the parts I just replaced such as tps, cam sensor and coil packs so I'm guessing I haven't driven it long enough to clear them out (only about 10 miles).

After researching leaking injectors I'm thinking that might be my problem, anyone know how to test which injector it is?

 

You have to clear the error codes with a scanner. They don't just go away.

 

I have no idea what can be causing this please help, it's kicking my butt.

Symptoms
-Cranks but won't start (not cps)
-Backfires out of TB and exhaust sometimes when trying to start but not always.
-sometimes starts and runs very rough then stalls.
-sometimes starts and runs fine.

Parts replaced
-ECU
-coil packs
-tps
-cps
-cam position sensor
-coolant temp sensor
-fuel injectors

On the occasions that it does start or at least try to start it seems like it's misfiring or out of timing or something. I'm considering a valve issue? But when it starts it'll usually run fine so I don't know... I'm very frustrated and confused. Any help is appreciated.

 

Did this start suddenly?

 

Mine did. Why do u ask?