You may have no spark when it does this, you can pull off a plug wire and attach to a spare plug laying on the manifold, check for sparks, no sparks would be CKP sensor.

 

As of now I am leaning towards a vacuum leak as I hear a whistle coming from the engine around 1900 RPM's.

Also, I think the engine is flooding after cutoff making it hard to restart. If I run then engine around 2000 RPM's and then cut off it will crank right up immediately afterwards, if I let it idle around 650 RPM's it will require a few rotations to finally start. Also the smell of gasoline in the exhaust is very strong when it starts. This heavy amount of fuel in the system would make the 02 sensors read lean correct causing the P0171 and P0174 codes.

Is it possible a leak in a vacuum hose is allowing the engine to flood? Pulling straws here and racking my brain trying to figure this thing out. I appreciate all the feeback that this has gotten and look forward to more. Thanks!

 

Check the rubber hose from the MAF to the plenum.
Check the clamps
Check the MAF is air tight on the hoses.

Check the brake booster vacuum line. Where it plugs into the plenum.
Make sure the red keeper and seal is on it.

There is a 2nd vacuum hose there too. Check that one.

Fix the exhaust leak.
If you can tighten bolts then give that a go

 

Today I took the truck to a mechanic to have him take a peek at what it is doing. He believes it is the upper intake manifold gasket letting air into the system. He is going to smoke test it on Monday and let me know what he finds. Does this sound like a logical explanation to you guys, it makes some what sense to me. Also, what is the price I would expect to pay to have this type work completed. I am not opposed to trying it myself if its not reasonable. Thanks again for your help.

 

Pretty easy DIY.

 

I am having a similar issue with my 04. I was driving yesterday and felt a couple noticeable surges and then when I was pulling into the parking lot it died and would not start. It cranked but no fire. I couldn't hear the fuel rail build pressure at position 2 so I figured it was the fuel pump. After 10-15 it started and I drove it straight home. The next day I was going to take it over to the shop to do some checks on it but it fired right up. I turned it off and the tried to restart it and it wouldn't fire again. I took the gas cap off and put my ear to filler hole and had the wife turn it to position 2 then nothing and it wouldn't start. Tried it a couple times and finally heard the pump turn on and then guess what happened...it started. So I am guessing it is the fuel pump but I am not sure if anything could be causing it to intermittently not work like a relay or a sensor? Would like to start at something cheap that I have as a replacement part off of the spare disco before I spend $$$ on a new fuel pump. Any thoughts? Thanks in advance.

 

The mechanic smoke tested it for me and found I have a small vacuum leak at the lower intake manifold gasket, a small leak at the brake booster line and i am missing a latch on the air box and leaking valve cover gaskets. To repair these items he quoted a figure of around $1000. Looks like I will be learning to replace gaskets on my own.

I do not believe this is the source of the hard start problem. It feels like a fuel issue. After racking my brain, could it possible be the Crankshaft position sensor. The fuel pump primes upon initial start in the morning. After it runs a while, when restarting you hear the fuel pump come on for about 1 second so I am assuming that the fuel pressure is fine and everything is primed. Then when you try to start it it hard starts, and will finally sputter to start like it needs fuel. Once it starts in runs fine until you turn it off again. Any ideas. I hate to go in and replace all of the gaskets just to find I still have the same hard start problem. All of this started very abrubtly so I do not feel as if a vacuum issue is the culprit.

Thanks in advance for your feedback.

 

Rover Dawg -

Valve cover gaskets may snug up, but are easy to change. Air box latch sold by on line vendors. Replace whole brake booster line.

If he pointed out the vac leak spot on the lower intake, try a dab of copper RTV. It is a vac leak, not pressure coming out.

To test the CKP sensor, put a spare spark plug on one of the plug wires and lay on manifold. Check for sparks when cranking. CKP usually shows up first when engine hot, then starts working when cooled off. Pour water or use compressed air to chill down.

 

"I do not believe this is the source of the hard start problem. It feels like a fuel issue. After racking my brain, could it possible be the Crankshaft position sensor."

I think you are dead-on about crank position sensor. And has been reported, you can test for spark when no start issue arises, but my feeling is, why bother? The crank sensor is likely a ticking time bomb anyway.

I changed mine less than a week ago, after a brief heat soak left me stranded, and immediately noted reduced crank times at start up. And, gas mileage went up with new sensor. This makes sense to me: better input data for engine management makes better fuel economy and performance. But the whole MPG thing might be better suited to a different thread.

 

Is your starter always engaging the fly wheel? As Savannah once said "there gets metal fuzz on the Crank Sensor". This could distort the signal.