[TXjeep97]

Ok guys, this may get a little long-winded...

1998 4.0 Auto

It started with and intermittent hard-start condition. Every once and a while my jeep would take a few more turns to start and when it finally would, it would stumble for a few seconds. After that it was smooth. So I used the search feature, found out it could be two things: crankshaft position sensor, or camshaft position sensor.

BUT, I read that usual symptoms of Crankshaft position sensor failure include stalls and the engine randomly dying while driving and what not. I didnt have these other problems, only the hard-start problem.

So I read about the camshaft position sensor, and found that it often leads to hard-start conditions. So does this rule out the crank sensor?

Also, would either of these sensors cause a short that would drain the battery if they went bad? My battery keeps dying and it came about all of a sudden. I've checked all other electrical connections and everything else looks good.

Thanks in advance and sorry it was so long...
Javi

[tjwalker]

Your symptoms don't fit either a bad crank or a bad cam sensor in my opinion.

Just brainstorming but three possibilities come to mind. Either you have a fuel delivery issue (bad fuel pump assembly allowing drainback, pressure loss at fuel rail) a leaky fuel injector or a bad battery.

1. Simple things first. Having a bad battery has in some instances, created long crank symptoms. Sounds weird but it happens. Fix your battery problem first. Even if that is not your problem and it may not be, you really do need a healthy battery to run all circuits on your XJ. Have it load tested, replace if necessary.

2. If you are still seing long cranks after verifying battery, try this. Turn the key to the ON position (do not crank). You will hear the fuel pump energize and run for a couple of seconds. Turn key to the off position. Repeat the above two more times. NOW crank the engine, if it starts cleanly, then I would suspect you are looking at a faulty fuel pump assembly. It is located in the tank on your 1998. PITA to replace.

3. If it is still "stumbling" upon startup, then one of your fuel injectors may be leaky and is flooding that cylinder with fuel. That does two things. First it can result in a longer crank as pressure in rail has dropped with the leak and secondly, the excess fuel in cylinder is too much to cleanly burn, resulting in the "stumble" until it cleans out the excess fuel.

Few things for you to think about. Good luck and post back what you find!

[butch(4355)]

Following the K.I.S.S. theory and my recent experiences....

First look in your throttlebody, is there black gunk (blowby residue) around the throttle blades?

I had a no idle problem, that, in hindsight the symptoms leading up to that was a hard start and momentary rough idle. As time passed it transitioned to a no idle phase. The solution was to clean the bore of the TB and replace the engine coolant temp sensor.
Basically the blades (in fully closed position)have a small clearance set for intake air @ idle, if this is restricted the car will idle like crap, or not at all and the IAC wants to compensate, thus the lag.

As to the battery situation. Start at your grounds and work backwards, checking for quality connections and open conditions, all the way to altn output. Also get your battery load tested.

Hope this helps

[TXjeep97]

I forgot to mention in my first post that the battery is BRAND NEW. I got it 3 weeks ago.

Here's the interesting thing: jeep started today. A slight stumble, but fired up every time.

So, its not the battery. Fuel pump is fine, I have no other symptoms that would indicate it was the fuel pump, and I can almost certainly rule out a leaky injector. It stumbles on almost every start, even using the little on/off/on/off trick to pressure up the lines. And i can turn it off and right back on and it will still stumble. Unless the injector is leaking like crazy, i don't think this is the problem either. Besides wouldn't this cause driveability issues?

Oh, and the thottle body isn't dirty, i cleaned it.

So now what?

[coppertop71]

Originally Posted by TXjeep97

Also, would either of these sensors cause a short that would drain the battery if they went bad? My battery keeps dying and it came about all of a sudden. I've checked all other electrical connections and everything else looks good.
Javi

One possibility is to check your glove box door and make sure it closes all the way and that the light switch works and shut the light off.