Starting issues

[Gogster671]

Hello Everyone,

I’m new here and I wanted to get some help with my 1999 Jeep TJ Sahara. I ran into a starting issue and it has been a nightmare since. I replaced multiple parts such as my CPS, Ignition Coil, plugs and wires, ignition switch and I am still only able to crank the Jeep without it turning over. I took apart the harness to check for any corrosion and exposure of any wires and they all are still intact. And help would be greatly appreciated at this point.

 

[CharlesHS]

When you turn the ignition switch to ON; you should hear the fuel pump run for 3-5 seconds.
IF not... then remove and swap the fuel pump relay and Automatic Shutdown relay in the engine compartment fuse/relay box (PDC) with the air conditioning relay that is also in the PDC.
Remove the intake tube attached to the top of the throttlebody, move the throttle to open the throttle plate and pour a little gasoline into the throttlebody, crank the engine and see if the engine tries to start.
IF the engine does not start then your problem is likely to be the fuel pump or the lack of spark.
Remove one of the spark plug wires and install a spark plug and ground against a part of the engine block, crank the engine and while cranking the engine determine if you are getting spark at the spark plug gap.
IF you are not getting spark then measure for 12V across the two wires on the ignition coil when cranking the engine.

 

[Gogster671]

When you turn the ignition switch to ON; you should hear the fuel pump run for 3-5 seconds.
IF not... then remove and swap the fuel pump relay and Automatic Shutdown relay in the engine compartment fuse/relay box (PDC) with the air conditioning relay that is also in the PDC.
Remove the intake tube attached to the top of the throttlebody, move the throttle to open the throttle plate and pour a little gasoline into the throttlebody, crank the engine and see if the engine tries to start.
IF the engine does not start then your problem is likely to be the fuel pump or the lack of spark.
Remove one of the spark plug wires and install a spark plug and ground against a part of the engine block, crank the engine and while cranking the engine determine if you are getting spark at the spark plug gap.
IF you are not getting spark then measure for 12V across the two wires on the ignition coil when cranking the engine.

I changed out the fuel sending unit because I was having a long crank issue before and recently tested fuel pressure and it was good. I have good flow of fuel to the rail. I tested for spark and I would get an initial spark but very faint if I didn’t crank the Jeep for a day or so but afterwards it wouldn’t show any sparks after the one crank.

 

[Gogster671]

I changed out the fuel sending unit because I was having a long crank issue before and recently tested fuel pressure and it was good. I have good flow of fuel to the rail. I tested for spark and I would get an initial spark but very faint if I didn’t crank the Jeep for a day or so but afterwards it wouldn’t show any sparks after the one crank.

I had also bought new relays but still no progress.

 

[CharlesHS]

You are either losing the 12V to the coil or more likely the coil windings have a lot of resistance giving minimal spark and the coil needs to be replaced.