A few months back my trusty 2000 Wrangler slowly developed a starting issue where you may crank the engine 7-8 seconds, get nothing try again and start. I figured it was nothing to get excited about as it has never stranded me. The symptom got steadily worse ( starting on third or fourth attempt) and I decided to take it in for a check up. The tech replaced the Idle Air Control valve,cleaned throttle body, IAC signal good,no vacuum leaks,crank sensor ok,ECT reads correctly,fuel delivery good, compression good all cylinders. He told me if the new Idle Air Control valve didnt fix the problem I should replace the Idle Speed Control motor(cost 47.50). The jeep started great for about a week, then occasionally gave a long start until finally four weeks later Im back where I started. Ive noticed you can go out , jump in and if it starts on the first try, shut it down try and restart it immediately it long cranks. I cant find a Idle speed control motor on the throttle body or in my manual. A guy on another site says the 2000 doesnt even have one? The engine is running a bit flat also and a friend of my wife's said the 10% ethanol was giving her a similar problem. Her mechanic recommended using quality premium gas for a couple weeks. But Im really curious to know if the 2000 Sahara uses both a Idle Speed Control Motor in addition to its Idle Air Control valve. This forum rocks!

 

You said he checked the crank sensor, what about the cam position sensor?

 

he never mentioned the crank position sensor and i see it can cause symptoms of my problem. He found no "codes" from the comp. to clear when diagnosing problem. could the crank pos. sensor be defective and still not display a code? It had a trouble free week right after he replaced the IAC valve then the problem slowly returned. After checking online I believe they charged me for a O.E. sensor (115 dollars) and probably installed a 60 dollar aftermarket part from Autozone. could it be bad out of the box? its stamped made in Mexico?? thanks for your time.

 

*he never mentioned the {cam position sensor } oops.

 

Well the cam position sensor in my 2007 was changed and I have not had that problem since. The symptom I had was like yours, long crank time, if I stopped and tried again it would start right up. Mine never gave a code, so it is possible to not recieve a code when the sensor is starting to go bad.
Sometimes I would go a week or more without it happening, other times it would happen a few times on the same day. Who knows, maybe your trouble free week was a coincidence. I would give the cam position sensor a try, it sure wouldn't hurt at this point.

 

the cam pos. sensor will be my next move.

 

ive replaced both crank sensor and cam position sensor with no improvement.
it will start right up about 1 out of 4 or 5 tries when cold and usually wont start up after immediately trying to restart it hot. iac valve has been replaced and fuel delivery is within specs ,injection is ok. any advice would be appreciated at this point. ive seen alot of ppl online complaining of these symptoms with the 4.0 wrangler. im told an oxygen sensor would give a trouble code and im getting none of those. im wondering about the coil packs integrated into the spark plug rail/bar cover?? or could a single bad spark plug create this problem? i used the o.e champions (cheap) but maybe should have tried better grade?? thanks if you have any comments. life goes on. it hasnt stranded anyone but the wife is spooked to drive it now,lol. peace...

 

anybody else notice that he's talking about a TJ? i'm not knocking it or anything, but i'm just saying this might help in diagnosing his problem being as how the 4.0 is completely different from the 3.8. i'm sure this will be moved to the appropriate part of the forum by a moderator, but until then, this is a very good point to keep in mind. and to the op, good luck figuring out your problem

 

If it's an idle air staying closed problem, try holding the gas pedal down just a crack to open the throttle body. If it still long cranks, it's most likely not an idle air issue. Also, when it long cranks, watch the check engine light. I've seen a few Jeeps with bad PCM's. When you turn the key on, the Check Engine light should come on. The ones I've seen long crank, the CEL would intermittently not come on, then while cranking long the light would pop on and the engine would start. So keep an eye out for that.
And yes, the advice I'm giving you is for late 90's 4.0 motors.
The PCM's have more of a tendency to mess up when it's cold outside.

 

In some cases the fuel system has a check valve that keeps fuel in the fuel rail. If the check valve is bad, it will allow fuel to drain back into the tank and cause long crank times. just a thot