Friend of mine has a 96 cummins he pulls at the county fair. turbo pushes about 35 lbs then the gauge starts going crazy (like up and down real quick) truck (to my knowledge) is fully stock, and turbo is in good shape. What might cause this to happen?

Thanks in advance!

Donizer

 

it is almost impossible for a stock truck to hit 35psi, pressure fluctuations would be due to the wastegate opening, trying to limit pressure, if the truck is infact stock, i would lean towards a bad boost gauge, is it electrical or mechanical gauge?

 

Well we think the boost gauge is ok because it wasn't running like she usually does.(normally makes 50 PSI when pulling) She wasn't really rollin the coal like usual either. I was thinking hairline crack in the inter cooler.

 

not putting out as much smoke

 

ok, well, its definitly not stock... 50psi on a stock turbo is bad news and a stock engine wouldnt push anywhere near that much boost or smoke, i would bet its a fueling issue, does the truck have a fuel pressure gauge?

 

It's a garret turbo, with cummins injectors out of a combine. #3 fuel plate, with water injection. double disc clutch, he normally pulls 5th gear
(not so stock after all)