Dosent like to start when its cool and damp

i have an 89 xj 4.0 it dosent like to fire when it is damp. It cranks fine but just floods. It started to fire but then quickly died. i then put the peddle to the floor and kept cranking and it started reluctently but then ran fine. I have never had problems starting it in any weather before. could this be a tps issue? it sometimes idles high around 2500-3000 on startup and wont drop but that happens randomly and not just when wet.

I've got a 95 and have noticed in the past cuople days when its been cool and wet mine cranks longer than usual before it starts but yours sounds completly different than whats going on wiht mine.

The wifes 87, used to that, most times it turned out to be weak spark, often there was, carbon dust and green stuff growing in the distributor cap. My 88 seems to run better when it´s wet, the wetter the better, go figure.
Might be worth your while to squirt a little penetraing oil (or most any lite spray oil), down the IAC port, while the engine is running. I usually dribble it down the port, seems to help some, on mine. A sticky IAC will also mess up your starts. I usually start mine with no pedal, when I suspect a sticky IAC, I start with about 1/8 th pedal, if it pops right over, probably a strong indicator the IAC is sticking (which is common) or possibly the latch relay is acting up (which is rare).
If your XJ sucks a fair amount of oil into the air filter, chances are the IAC is covered in sticky stuff.

I'd also replace the distributor cap and rotor. Maybe spray some WD-40 down inside the distributor. Also check the wire going from the coil to distributor; if it has high resistance, I'd replace it. Resistance in plug wires should be less than about 12K ohms per inch.

Also try spraying some WD-40 into the electrical plug for the ignition module/coil assembly.

did you find out whats happeneing? i have the exact same syntoms on mine. same truck 89 4.0

Check your spark plug wires. Use a spray bottle with the engine running. Mist the plug wires and check to see if the engine sputters.

edit: I just saw the original post date. Oh well...

thats fine i got the same probs.... wont start when its damp out... cps resistance checks out ok and the AC voltage matches up with my buddy's who just put a new one in... beefed up the batt terminal cables with some zero guage cable and marine style terminals. (old cables were in bad shape) also redid the grounding strap with some 0 guage... going to direct ground the alternator with the leftovers when i get time... gonna run thru the gauntlet of sensor tests soon since its freakin january and 70 degrees out in jersey.

any particular ones to test first?

plug cables are good and the dist cap is as well. gotta test the coil i suppose.

Resistance in plug wires should be less than about 12K ohms per inch.

Click to expand...

Man, what a typo. I meant to say per FOOT.
:anon: