Engine/Transmission (1994 - 1998) Black Smoke, Low Boost

[Big E]

My buddy has a 97 Dually. It has a TST kit (can't remember which) and EGR is deleted. Truck recently started blowing black smoke, with low boost pressure and reduced power. My first thought was the intake hoses. He found one with a small hole in it, so he installed all new hoses and clamps. This did not solve the problem.



A couple weeks ago, he jumps in the truck to drive it my house to have me look at it. Now the truck runs fine. 30 psi boost, no smoke, normal power.



He just texted me and says the truck is doing it again.



Any suggestions on a possible cause???



The air filter is clean, so that's not the problem.

 

[Missouri Mule]

Does he have a exhaust brake? (Especially a Pac Brake) The potato gets stuck in the exhaust/down pipe.

 

[Big E]

He does not have an exhaust brake.

 

[JKosten]

It sounds like the governor arm in the pump could be hanging up on the fuel stop plate he put in, and overfueling.

 

[S.Morris]

Does it have a waste gate and is it sticking open

 

[Big E]

Thanks for the replies. I'm not sure when we will be able to get together again to troubleshoot this. I will post a reply when we solve it.