ATIBlownZ71

Got the new 6.0 in last weekend. Ran like a champ for 2 days then went out to start it and all it would do is crank. Started going thru all the testing procedures for a no start. Has good fuel and good spark. All sensors test out ok. Motor spins freely. Just will not fire! This one has us stumped. Is it possible since the crank is not keyed for the timing sprocket to spin on the crankshaft? One of the guys threw that out as a idea. We manually played with timing in HP Tuner but still couldn't get it to hit, so if the cam is off, it's way off. Any ideas guys? Appreciate it!

budhayes3

iTrader: (19)

I thought that the timing gear on the crank was keyed, just not the crank pulley? I would think that if that gear moved, you'd definitely have a problem...and possibly wierd timing, crank, and cam sensor readings.

ATIBlownZ71

It shows 18 degrees when cranking it. I retarded it all the way to -10 and it didn't have any kind of effect on it. Went the opposite way and added 10 to it and still the same thing. Lol we even have a local GM tech scratching his head on this one. he hooked it to his Tech2 and even it doesn't show anything abnormal.

Ruffrider5.3

I would think if your timing chain broke it would make a helluva racket, the crank sprocket is keyed by the way, if nothing showed up electrically then maybe it is some valves staying open or something else mechanical.

ATIBlownZ71

Couldn't remember if the crank was keyed or not. Timing chain is brand new Rollmaster double. Valves aren't sticking. Although now you got me wondering if the pushrods are bent. Pretty much everything on this 6.0 is brand new and what we thought was carefully assembled. I wasn't there for the seeting up of the valvetrain so thats the only reason why I wonder about the pushrods. The rockers and lifters are Crane.

Ruffrider5.3

If a pushrod is bent then you more than likely have a valve that is sticking open. If you have one valve sticking it should still start up but will not do much else but die. Maybe valve train has something wrong that would explain why it ran fine and now it doesnt, maybe a rocker came loose or something of the sort.

Deckhand

iTrader: (1)

air, spark, fuel.. you got the fuel?

ATIBlownZ71

Has 54psi@the rail. Pull the plugs and it compresses out the plug hole. Spark is right on the money too. Oil pressure was great when it ran. We originally thought when the new crossover pipe got welded up that computer got spiked. We changed out the the pcm, bcm and tac with known good units and still wouldn't fire. Thought maybe it was vats screwin with it so disabled that in HP Tuner....still nothing. The motor spins so freely that it doesn't sound like sticking valves.

NXRICKY

iTrader: (1)

Check all fuses, the injectors do not sound like they are firing since you have pressure.. To test this, you could put a very small (small) amount a gasonline at the throttle body connecting to hose.. Then crank it, if the truck coughs, or fires for a second, you know the injectors are not... Remember just a small amount...Thinking old school carb. stuff..
Ricky

budhayes3

iTrader: (19)

That's some good advice...also, are there any codes? Just wondering since the engine's been out of the vehicle if the reluctor ring on the crank came loose causing bad spark timing, although you'd think it would at least sputter when cranking.