I posted this last night on LS1Tech but I figured I might as well post it here too.

Ok I am out of ideas, so here is the story hopefully I can get some help with this.

First - The vehicle is a stock 1998 3/4 Ton 2WD with the 5.7L Vortec with 240k miles.

Second - History of maintenance plugs, cap, rotor & coil were changed about 2 years ago due to age. Last year the distributor gear died and was replaced. It drinks oil, about 1 quart every 1,000 miles or so and I have no idea where it is going. Other than that it has ran perfectly.

Third - The problem, it will not start. I filled it up almost two weeks ago and drove it to work, 100 mile round trip, last Monday. The weather was nice the rest of the week so I drove my car until this week. Yesterday I went to start it and the battery was dead, not completely but not enough to start it either. So I drove my car again with the intention to get the truck running after I got home.

I set it up for a jump and tried to start it, turned over for about 20 seconds then battery dead again. Waited a bit longer and I tried again more juice this time but did not start before battery went down. At this point I switched over to a battery charger and gave it an hour to charge. Now is when the fun really begins.

With a good charge the truck still will not fire, this is not normal so I started checking off the list, fuel good, spark good, try again this time I get frustrated and decide to give it a little boost with some starting fluid, nothing. I wait awhile in case it is flooded, still no good it is not even coughing. So I did what any redneck would do, I start trying to fuel it manually. This time I got some results it sputtered a little, so i gave it some more fuel and cracked the throttle while starting it and after a few seconds I get a 3' fireball out the throttle body.

Too much fuel I thought, so I quit adding fuel. No difference except that if i pump the gas while trying to start it I get back fires through the throttle body and occasionally an actual fire in the intake, these are quickly extinguished by releasing the throttle.

Now I am thinking it has something to do with timing, so I start going over everything from the spark plugs to the crank sensor checking for loose or damaged wires. Everything looked fine, except the spark plugs were a bit wet. I plugged my scanner in and there were no codes. At this time it was 5am and I had to get up at 6 to go to work so i gave it a rest.

Today I scoured the internet looking for similar issues, mostly finding either insufficient fuel pressure or sensors. On my way home I picked up the tools I needed to check the fuel and sensors. Now I have the truck in the garage with plenty of light and at least some heat.

Fuel pressure checks out ok, 60psi. Ignition control module and ignition coil both getting power and operating. Crank sensor plug was covered in something mostly water, had some wonky reading on it so I replaced it just in case. Cam position sensor operating properly. Pulled the plugs, wires and distributor. Plugs were covered in what appears to be mostly oil, cleaned and reinstalled. Wires and distributor look good reinstalled. While I had the plugs out I checked compression on 1, 3, 2 & 4 all around 150psi, the same as they were 2 years ago. Checked the fuel seemed a little strange, I did throw a can of seafoam in the tank earlier, compared it to fresh fuel and it burned twice as fast as the fresh fuel. Tried to ignite the wet plugs, no go they would barely burn, every time I cranked it after one try the plugs would be covered again. After all this the truck will pop, mostly from the intake but a little from the exhaust as well, but not kick over. Still backfires from the intake.

I have a jar of fuel I am going to let sit overnight and see if anything separates out. My only other theory is what if my lifter have collapsed after sitting for a week and the valves are not opening? Barring any better suggestions I am going to pull a valve cover tomorrow and see what is going on there. Other than that I am at a loss I have fuel, spark and compression. I have twisted the distributor every which way I can and all I can accomplish is a decrease in the number of backfires through the intake. I just do not understand what could have caused the truck to do this by sitting for a week. Long post I know but I felt that I should detail everything I could to help in hopefully getting some help on this.

Actually the more I think about it the more sense valves not opening properly makes. It would explain why fuel fills the intake and why the wet plugs do not burn very well. The small amount of fuel that does get into the combustion chamber combines with the oil and does not fully burn before the intake valve opens again igniting the fuel in the intake. Now the question I have is is that possible?

The bottom line is that I have compression and spark that seems to be occuring at the correct time, I have at least some fuel (mostly in the intake though). The truck acts like it is out of gas but I've been there done that and I have about 20 gallons in the tank.

Update: No moisture or crack in distributor cap some slight corrosion I cleaned it up before reinstalling. I forgot to check the fuel I left out over night to look for any seperation but I am not really expecting much.

 

I just had a bad experiance with sea foam but it a Fuel pump relay and another fuse fixed it. My truck would act like it was not getting any fuel last night. There was a fuse that I think its the pcmb fuse that I also repalced under the hood then deleted the ses errors witha hand held reader and truck started right up. While I was trying to get the truck tostart I did have it jumped to another battery that was in a running car.

Does the Crank sensor have to be relearned? Wifes SUV had a bad crank sensor and it also acted like it was starved for fuel. Until it was replaced and a dealer came to the shop to so call relearn it, the suv would not start 90% of the time.

 

check fuel pressure,depressing the schrader on the fuel line not accurate enough./ are you getting spark at the plugs themselves. (bright blue spark)

 

Personally I have not had a bad seafoam experiance yet but there is always a first time. I checked all the fuses and relays the first night and everything was good. Yes it will need a relearn but that should not stop it from starting, there was no difference in behavior after I put the new one in.

What I can't figure out is how I cannot get anything out of it at all. It went from running perfectly fine one day to perfectly dead a week later. Even my first optispark failure produced more results than this.

 

Yes I have ~60psi with the key on slightly less while trying to start. I have plenty of spark at the plugs bright blue and can see it in the daylight, they even spark good while wet after I take them out of the motor. Spark is not an issue, when the spark is occuring might be but it seems fairly close. Pulled plug and felt for the compression stroke while watching for spark, it seemed to be pretty close to correct.