LLY: black smoke on heavy acceleration

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New member
Sep 25, 2016
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My son recently purchased an 05 Silverado HD. It had an issue on starting so we replaced fuel filter and cap, lines going in and out and:) clamps because it kept loosing prime as soon as you shut the truck off. Then a fuel leak sprouted and we replaced the passenger side fuel injector return lines. It has had an oil change and a new air filter installed. He did the bottle test on the valve in the fuel rail and nothing leaked out. My son informed me that when he hits 2k rpm the truck slightly bogs down. It also blows black smoke on heavy acceleration. The truck has no codes stored on the computer and the check engine light is not on. The fellow he purchased the truck from replaced the pump gear, 2 injectors and fuel sending module. It still does not start right up, it takes about 15 seconds. I was wondering if anybody has any idea of what could be causing this. He thinks it might be tuned. Is there any way to find this out? Appreciate any help. Thanks.:)
 

DAVe3283

Heavy & Slow
Sep 3, 2009
3,729
297
83
Boise, ID, USA
Only way I know to find out if it is tuned is to read out the tune in the computer, and compare it to a stock one. Might be able to find a member in your area with EFILive to do it for you, or a shop.

The long crank can be caused by continued air leaks, a failing CP3 (fuel pump), or failing injectors. It sounds like you are still fighting an air leak, so I would address that first.
 

Burn Down

Hotrodder
Sep 14, 2008
7,092
28
48
Boise Idaho
I'm with Dave, sounds like it's still sucking air. How many pumps on the filter primer before it gets hard to pump. Immediately after pumping the primer till it gets hard try to start the engine. Did it fire right up or have a long crank time again?