Jeep won't start unless I push start it

[Millertime33857]

After reading numerous other threads on this topic, I’m still having trouble. My Jeep will turn over all day long but won’t crank. The starter and fuel pump are less than a year old.
I’m getting fuel to the rail and cylinders.
Ive got spark
My battery has over 12 volts
I’ve replaced the crank sensor
I’ve replaced the cam sensor
I’ve checked the o2 sensor fuse
I’ve cleaned the throttle body
There’s no “check engine” light so I’m not sure it’s throwing any codes.
Here’s the thing. When I push-start the Jeep it runs fine w/ zero issues. Any help is appreciated.

 

[Chris]

First and foremost, what year is it, what engine, and what transmission?

Start by checking for spark. If it's a coil pack, there is an easy way to test the coil pack:



Once you've verified you're getting spark, test the fuel pressure at the rail and tell us what the fuel pressure is.

That's the first two things you need to do, make sure it's getting fuel, and make sure it's getting spark. Those need to be ruled out before going any further.

 

[Tomcat]

Is it just me or what. I have no clue what their saying. I'm as confused as a blind homo in a wiene factory.
Maybe I had stroke or something.

 

[Millertime33857]

It’s 03’ w/ a 4.0 , manual transmission. I’ll check the coil pack. I’ve got pressure at fuel rail via the Schrader valve but I haven’t put a gauge on it. Given it runs fine after I push-start it, is spark and fuel pressure still a possible culprit?

 

[Chris]

Okay, I missed that bit about not running unless you push start it.

So the engine turns over when you start it, but it won't fire up? However, if you push start it then it runs just fine?

I don't know, almost sounds like a bad starter to me.

 

[Millertime33857]

Correct. And starter is 6 months old. Thought is could be bleed back valve but again-fuel pump assembly was replaced last summer

 

[AMS417]

It is cranking slow, fast, uneven? Check the compression. Had an old Datsun 510 years ago that would run if you push started it, but the engine was tired and compression was low enough it would not fire up off the starter most days.

 

[Millertime33857]

It sounds strong when I try to crank it

 

[Jerry Bransford]

I am always completely confused when anyone uses crank and turn over terms to describe two different things. To me both of those describe the same thing... getting the engine spinning so it can start.

Are you saying the starter motor is not even turning over/cranking the engine? Or it is getting the engine to spin but it isn't starting?

 

[Millertime33857]

I am always completely confused when anyone uses crank and turn over terms to describe two different things. To me both of those describe the same thing... getting the engine spinning so it can start.

Are you saying the starter motor is not even turning over/cranking the engine? Or it is getting the engine to spin but it isn't starting?

 

[Millertime33857]

The latter Jerry. It’s getting the engine to spin but not start.

 

[BuildBreakRepeat]

The latter Jerry. It’s getting the engine to spin but not start.

Sounds like hard start. If speed and dropping clutch starts it but starter doesn’t, it’s not spinning the engine with enough force, or the timing is off such that it only can start with a massive force.

 

[CharlesHS]

The START (crank circuit) is separate to the RUN (operating circuit); you may have a problem with the power supplied to the ignition when cranking the engine to start.

 

[Mjv]

If starting voltage is too low most of the voltage will be consumed by the starter and there will not be enough to light the engine. Thus push start works. Starter could be over drawing?

 

[Noreaster1967]

I had a Mustang that was like that. It ended up being corrosion in the negative battery cable, about halfway down, where they grounded the cable to the frame.

 

[Vinman]

The START (crank circuit) is separate to the RUN (operating circuit); you may have a problem with the power supplied to the ignition when cranking the engine to start.

I’ve had a couple of vehicles do this, power to the coil when the ignition was in the run position but no power while engine was cranking (ignition in start position)
Sounds like an ignition circuit problem

 

[John Scoggins]

Sounds like the ignition switch as given up

 

[Millertime33857]

I’ll

Sounds like the ignition switch as given up

I’ll check this out and let you guys know

 

[Millertime33857]

Sounds like the ignition switch as given up

Replaced the ignition switch and it starts like it should. Thanks so much for the help all!