hello to all.i didnt really want my first post to be a "starting problem", but here i am.i have recently purchased a 99 xj classic 40. auto. to day i placed a new optima under the hood assuming the old battery had retired.got the same thing with the new battery.i can smell fuel,and im sure it idled at a very low rpm pretty rough for just a few seconds.she seems to have spark.i figured id ask the dudes in the know before i stand out in the cold and tear **** apart.a appreciate any help.

 

anyone?

 

Double check all the ignition parts. I.e plugs wires cap rotor the whole nine, it sounds like your getting plenty of fuel so that's where id start

 

ive already checked all of that.im told its likely the crank position sensor.but im also told the cps will throw a code and the "check engine" light will come on.the light will only come on when im cranking it.according to what ive read,that indicates to me that the throttle position sensor is faulty.unless then fuel smell kills that idea.

 

you should check for codes any way even if the light is not lit>

 

A bad crankshaft position sensor would cause it not to start/idle at all, and the check engine light rarely comes on if it is bad. I very much doubt this is your cause (although don't rule it out completely - failure can be intermittent).

Does it crank at what you would call a "normal" speed? Does it start if you hold down the gas pedal while cranking?

 

1. You need to INSPECT your spark. Pull a plug, keep it attached to the plug wire, place the plug electrode near a good engine ground, have a buddy crank the engine while you watch. You are looking for a strong, BLUE, snapping spark. Yellow/orange/white indicates a weak spark, which can be problematic (ignition coil is suspect here).

2. How did you verify your tuneup hardware? Fresh plugs, wires, distributor cap and rotor before you chase your tail here.

 

the tune up bits are fresh.it wont idle at all and it cranks normally.

 

Do this.

 

I highly recommend pulling the codes. If you get a crankshaft code and two more related to transmission, it's the crank.

I did a transmission swap and had to use the crank from the old transmission I swapped in for 4WD. Cleared up all three codes and it actually idled like it was supposed to.