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Jeep starts only when it wants to

TonyBoom

NAXJA Forum User
Location
Richmond, IN
Alright guys, I was referred to you after discussing my intermittent Starting problem with another jeeper.

Here's the skinny:

My 1993 Jeep Cherokee Sport runs fine (well, fine enough). The problem is starting the damn thing. Somtimes it is as simple as turning the key and she starts right up. Other times, however, it chugs and chugs until a puff of bluish smoke comes out and she starts up. When this happens, my fuel pressure gauge and volt gauge appear to be a little lower than normal...after a few minutes of driving all is well.

Like I said, this is starting to happen more and more frequently. Every so often it is so hard to start that I start to lose the necessary voltage (usually after trying to start it for 20 minutes). But, I can always EVENTUALLY start it by pumping the gas and what not.

I have replaced CPS, Battery, Starter, Distributor.

I could go on with more info. But is anything jumping out to anyone?

Thanks
 
. When this happens, my fuel pressure gauge and volt gauge appear to be a little lower than normal...after a few minutes of driving all is well.


But, I can always EVENTUALLY start it by pumping the gas and what not.

Thanks

Do you have a fuel pressure gauge on your dash??


...and, you have a fuel injected vehicle, no need to "pump the gas". As a matter of fact, leave your foot OFF the gas. It will eventually have the right mixture of fuel, spark, air.

Meanwhile freshen your grounds, tune up??
 
A whole bunch jumps out at me as a matter of fact...lol
here's the short list

1. X2 stay off the gas peddle. Its fuel injected there should be no need to touch the gas pedal
2. Is the check engine light on when it is running...if yes..have the codes been read yet..what are the codes
3. when was the last time you did an air filter, fuel filter, cap and rotor, plugs(copper champions), wires, etc. (a basic FULL tune up)
4. check all your grounds, off top of my head the 3 major ones are--battery to block, back of cylinder head to firewall(bulkhead), battery to passenger fender.
5. Have your ignition module checked at one of the auto parts stores that you trust
6. BLUE smoke is usually associated with the oil. How is your compression in the cylinders?
 
Having to tip in the throttle to start it is a pretty common symptom of a "throttle position sensor" problem.

That being said, be sure that all tuneup hardware is fresh, be sure you have FRESHENED grounds, be sure your battery is strong (load test it).

If it still acts up after that and if there are no check engine light or stored codes, TEST your throttle position sensor

Testing for compression is never a bad idea, as it is a good "snapshot in time" of the general internal condition of the engine. The spec. for the 4.0 is 120-150 psi, with no more than a 30 psi variation between cylinders.

Good luck!
 
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