Quick Hummer Question

[fsSnowboard]

Ok, A friend is rebuilding the motor for a Hummer. I think it has a 6.8L Duramax. Anyways, he said it is dumping tons of smoke and has no power and that the smoke just falls to the ground and smells like fuel. He thinks that there is something wrong with the pump. He had the pump rebuilt at a local shop here andf thinks they might have messed something up. He said the smoke is kinda a whitish gray color. Anybody have any ideas?

Thanks

 

[The Warden]

IIRC all Hummers have the 6.5l Detroit for an engine. The early 6.5l's have basically the same fuel injector pump that our IDI's have (although the rotation's in the opposite direction); after '94 or so, an electronic pump was used.

Has he checked the injection timing? Is the return line system clear of obstructions?

Just a couple of thoughts...also, is there actual fuel leaking anywhere, or just the smoke?

 

[ErikHalvorson]

Not true. First Hummers to the public had 6.2 liter N/A engines. I am the guy he is talking about... Anyway, the orignial 6.2 N/A motor was run long on oil and low and hard and it spun a rod bearing. Then parked for nearly 2 years. It fired when I went to pick it up. Everything "ran" fine except for the squawling rod bearing. We re-engined the rig with a new GPE 6.5 N/A engine. Reused all of the 6.2 configured gear (pump, alt, h2o pump fuel pump etc) so it still has the mechanical injection. We had the injectors refurbished as well as the pump. Had the pump checked for sufficient volume capability to feed the slightly larger 6.5. We got everything back together, no lift pump. Relay gets power but no signal to the lift pump. We hot wired the lift pump and will look into that later. Anyway, bled the air from the system and it finally fires.... Lots of grey smoke. I mean like fogging for mosquitoes thick. Play around with the mechanical rotation of the pump to try and see if timing is off/close. Makes no difference whatsoever, advanced nor retarded. It is very hard to start no matter if it is warm (125 degrees... from idling) or fresh in the morning. No power either, though we can idle it onto a trailer or up the driveway into the shop. The longer if idles/runs, the worse it smokes. It is not water vapor from the cooling system. No bubbles in the system at all. Is the Volume screw cranked all the way open on the pump or did the injection pump shop screw the pooch on the pump re-assembly... or what....? We haven't checked the return line yet. The smoke is completely formt he exhaust and I mean large obnoxious quantities of it like ticket getting quantities...

 

[Camarogenius]

I'm digging into my memory here. If I recall, there are two styles of 6.2 injectors, and the pump has to be tuned to whichever style injectors you have.