Need Some Help
 

Just purchased a 89 Cummins. Ive got a few questions that I've not been able to find answers to so maybe you guys can help, and I apologize if they are dumb, I'm not familiar with the 12v but I'm trying to learn.

Ive found the truck has a Denny T stage 2 fuel pin, I added a 4inch turbo back. The truck doesn't have a afc spring, do I need to buy one? Anyone have a P/N?

Also the truck will make around 20-22 psi and it's almost like it will cut fuel. It will build right back up to 20-22 and dump again. It has had pump work done by the previous owner and I'm not sure what all he turned. The truck does idle high so I assume the power screw was turned up but I'm unsure.

Anyone know why it would only make 20psi? Thanks in advance. 🍻

Is the 20-22 psi boost pressure?

What turbo do you have? Wastegate?

How smoky is it?

The Hungry Diesel can supply the spring or a stiffer than standard if required.
Do you have a fuel pressure gauge and EGT gauge?
What RPM does it "cut out"?

20-22 psi of boost.

Factory h1c (smaller) version I believe since it's non ic

it smokes only until the turbo lights which is decently quick.

I have egt and boost only right now.

Im not sure on rpm but on the fuel cutoff solenoid , I believe the wire going to it has a short. If I am wot and around Max (20psi) boost the truck will die. It turns over until I move that wire. At that point it'll fire up and run fine, until it's under a load (wot)

Maybe not a short so much as a bad connection or broken wire, does any of the throttle system touch that wire?
Could try gutting the FSS and seeing if the problem goes away, maybe a faulty solenoid.