91 won't start

91 4.0 5spd will not start and occasionally coughs.I have replaced tps,cps,distributer,cap,rotor,spark plugs,fuel pressure regulator,map sensor,I have spark and fuel but no run.How do you check the computer
and if bad which one should i buy aftermarket or dealer?
It was running ruff and rich before i started on it because of fuel regulator.Could the injectors be bad also?

TIA
Sponge Bob

Have you tried to read the trouble codes from your computer if any? You can't do this on my '89, but I *think* it'll work on yours though (see link below). If it works, maybe there will be some clues?

http://go.jeep-xj.info/HowtoECUcodes.htm

So far i only get a code 33 for the AC clutch

distributor might be 180 degrees off.

oh yeah, could be dist off by 180 degs like 89xj said. did you remove the dist or anything else when it happened? or did it just stop running one day?

oh one more thing... will it run for a few seconds if you spray starting fluid into the intake hose? (or carb cleaner / brake cleaner in a pinch). If it does run for a bit, at least you know it's not ignition related

If your getting spark and getting fuel, then your problem sounds like timing. Every problem I had with my XJ starting was either no fuel or no spark. Recheck your spark plug connects. I remember when I replaced the ditributer, I put it back in wrong. Once I got it right, it putter fine.

I have set the timing several times still no luck.The jeep was running poorly and missfiring.My first thought was the TPS because when i checked it with a meter the voltage was not smooth.Now it won't run at all and the only things left to change our the computer and starter but it seems to be cranking fine!!!

Sponge Bob

Spongey -- you mention new plugs --- are they absolutely new? (or did you run rich on em for a while)? could be that they're fouled>?

You're certain that you got the firing order back in there right, and all -- have you checked timing with a light while cranking?

(if it cranks fine - your plugs should be wet and "gassy" smelling after a little bit of cranking ...)

Also, I had a distributor rotor fail on me once -- you could check-for and verify spark at the plug wires, but the timing was just plain odd -- the failure was very mechanical (the attachment points for the metal portions had failed allowing the rotor to spark an adjacent tower)

Have you disconnected the battery to clear any stored computer issues?

(sorry, I these are all WAGs - but maybe they'll spark some addition thoughts...)

did you check timing with a light or did you remove the distributor and reset it. i had to reset my distributor a few times before i got it exactly correct. with 180 degrees out it will not fire. with just 1 tooth off it will start but runs like crap.

UPDATE!!!!!!!!!

Blocked cat causing to much back pressure caused by faulty fuel pressure regulater making it run to rich.I hacked off cat and reconnected with pipe till i get it to the exhaust shop for replacement cat.

Thanks guys

Sponge Bob