03 4.0 Cranks, fires, dies and then only cranks

[Clarkey1986]

I know there have been a few threads about something similar but I have yet to find a solution to my issue. I am going to try and include as much information as I can here. The truck is a 2003 4.0 SOHC. It ran as long as I have owned it and then, one day, I hop in and it fired immediately but then died. Didn't even go to idle, just died. Tried cranking it over after that and all it would do was crank, no sputtering or attempts to fire. If I walk away for a day, it does this all over again. I walked through initial ignition steps I saw posted on another thread (turn the key on, CEL should light indicating PCM works, CEL should turn off when cranking) and everything checks out. The Theft light appears when the ignition initially turns on but turns off and doesn't come on during cranking.

Spark. We grounded the plug to the engine and saw spark in both of the plugs we pulled while cranking. I didn't pull anymore, I figured this was enough to, at least initially, rule out spark.

Fuel. Cycling the key to build initial fuel pressure does not make a difference, only leaving it for several hours will the truck light off again. I sprayed brake cleaner directly down the throttle body while my buddy cranked the engine. Sometimes we would get some very minor sputtering but it never really fired. I don't have any experience starting a vehicle with fluid in the TB so I could be doing something wrong here. It sounds pretty fool proof but, you never know. There was a noticeable puffing noise in the intake when cranking without fluid. I have yet to be able to get the fuel line off the fuel rail to test the fuel pressure. We removed the fuel filter and cycled the key, good fuel flow from the line. I dont have a pressure reading on it but it seemed strong. Fuel filter was replaced.

Compression I have yet to test.

Cam and crank sensors have been replaced.

This is where I currently sit. Anyone have any ideas? The fact it wont fire with brake clean has me suspicious since spark was confirmed. Other than that, I'm thinking it has to be something electrical at this point.

 

[franklin2]

There should be a port on the fuel rail where you can put a pressure tester. It looks like a tire valve. It's crowded in there, but keep looking, it should be a part of the metal fuel rail somewhere.

 

[Clarkey1986]

Thanks, its definitely crowded in there. I will have another look.

 

[polar8825]

Spark, fuel, everything seems to be working normally but no fire. Neutral safety switch maybe? Turn the key, shift all the way down the range & back then try again. Also, try starting the truck in neutral before making the effort to craw under the truck to test the switch with a multi meter.

When my shift cable started to go south, my truck would act up from time to time. At the very least, it's a quick & easy test.

 

[alwaysFlOoReD]

I know there have been a few threads about something similar but I have yet to find a solution to my issue. I am going to try and include as much information as I can here. The truck is a 2003 4.0 SOHC. It ran as long as I have owned it and then, one day, I hop in and it fired immediately but then died. Didn't even go to idle, just died. Tried cranking it over after that and all it would do was crank, no sputtering or attempts to fire. If I walk away for a day, it does this all over again. I walked through initial ignition steps I saw posted on another thread (turn the key on, CEL should light indicating PCM works, CEL should turn off when cranking) and everything checks out. The Theft light appears when the ignition initially turns on but turns off and doesn't come on during cranking.

Spark. We grounded the plug to the engine and saw spark in both of the plugs we pulled while cranking. I didn't pull anymore, I figured this was enough to, at least initially, rule out spark.

Fuel. Cycling the key to build initial fuel pressure does not make a difference, only leaving it for several hours will the truck light off again. I sprayed brake cleaner directly down the throttle body while my buddy cranked the engine. Sometimes we would get some very minor sputtering but it never really fired. I don't have any experience starting a vehicle with fluid in the TB so I could be doing something wrong here. It sounds pretty fool proof but, you never know. There was a noticeable puffing noise in the intake when cranking without fluid. I have yet to be able to get the fuel line off the fuel rail to test the fuel pressure. We removed the fuel filter and cycled the key, good fuel flow from the line. I dont have a pressure reading on it but it seemed strong. Fuel filter was replaced.

Compression I have yet to test.

Cam and crank sensors have been replaced.

This is where I currently sit. Anyone have any ideas? The fact it wont fire with brake clean has me suspicious since spark was confirmed. Other than that, I'm thinking it has to be something electrical at this point.

Try holding the gas pedal to the floor after the first initial firing. This will kill the injectors and tell you if the engine is getting flooded with fuel.

 

[SenorNoob]

There was a noticeable puffing noise in the intake when cranking without fluid.
...
Compression I have yet to test.
...
The fact it wont fire with brake clean has me suspicious since spark was confirmed.

Considering just those 3 sentences and 4.0 SOHC has me concerned...