Cummins ISM not reading boost correctly?

[Mikesuburban1]

(02-28-2017 )Magard Wrote:  Have you tried a different map sensor. Seems like your manual gauge is tell on the map sensor. Even if it's new doesn't mean much. It might be functioning good enough to not throw a code but not showing full boost. I would say a map sensor hardly ever throws a code unless it is broken. The computer probably blames something else for its faulty information.

I changed the manifold pressure sensor and no diffrence. I remembered there is a small brass screen filter in the top of the fuel pump, i took it out and it was pretty black so im gonna see if i can get a new one tomorrow along with some new fuel line