I recently acquired a 2004 3500 2wd w/ allison auto. It will turn over, but not start. Fuel is up to the filter. Pump the little hand pump until it is tight. I put my computer code reader on the thing, but I can't get a signal from the computer. Is there any way to tell if the computer is good without the port? I have tried 2 code scanners, but neither will come on with this vehicle, but work with my car.

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Oh, I just read the VIN and it is the LLY engine.

 

Replace the cigarette lighter fuse, the OBDII port draws its power from there. And see if you can get codes after that.

 

I got the scanner to work. cigarette lighter was shorted out. No codes. Everything says pass. I primed the fuel system, checked all the plugs I could, everything seems ok but it just spins over. The only thing I see that isn't right is the oil pressure gauge stays to the far right, pointing down and right.

 

crack injector lines 1,3,4 and prime it several times then tighten em up and try again.........should fire

 

New fuel filter yes? Does the exhaust smell like fuel at all when cranking, if so it could be an injector hung open keeping it from firing. one way to check that is to pull the glow plugs and turn the engine over and if they are hung open fuel will come flying out.

Can you observe the rail pressure while cranking the engine over with your scan tool?




u dont want to do that, and 1,3,4 are the hardest to get to with the engine and components fully assembled they're buried under crap

 

So another guy on another forum had a bad security circuit issue, and did a security "relearn". KNow anything about that? He said he didn't have a radio, put one in from a salvage yard, did a relearn and it started right up. And I have no way to smell the exhaust while I am cranking, it is outside, but I don't smell trace amounts of smoke when I get down there. This has the exhaust that dumps underneath in front of the axle.

 

heres a thread https://www.dieselbombers.com/chevy-...acing-ecm.html about the "relearn procedure" post #3

 

Did the relearn thing. Now how tight is the manual prime button supposed to get? Seems like it is now losing prime?? When I crank it, the button goes back to very easy to push like when you open the bleed screw.

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Oh, and still no start. Did not smell anything at the exhaust end of things. Don't know if it is getting fuel through the system.

 

I now see this is a Duramax................I thought you had a Cummins....sorry dude but scrap everything I said earlier

 

check all fuel connections for leaks. around the fuel filter and such