3406b low boost and fuel pressure issues

Hows it running?

 

I assume you've run this truck a bit, or have you just bought it?

 

Doesn’t really sound like fuel pressure to me. Is it chopping or smooth. If your running a spin on water separator change it to the washable CAT screen that will help it noticeably but isn’t why it lost boost.

I would check the pyro. With multiple boost leaks/intake gaskets pushed out it should have run warmer than 750 for sure.


I haven’t heard of a Mississippi red hot turbo, but that doesn’t mean anything.

What’s the serial number 8PN? Bottom of pump on back is a brass lug looks like it doesn’t fit no wires to it. Take a regular test light (led wont work here) and hook the clamp to battery positive. Put the probe on this brass lug. With the motor running wrap it to wide open rapidly. The light should light before the govnor catches it. If so that says rack is opening all way. Also make sure the break over spring isn’t broke and make sure when pushing throttle in cab it opens all way at pump. That 3/8 bolt can come loose and cause a little hell. If that checks out pull the cartridge out the hot side of turbo and see if it spit something out

 

Spec on fuel pressure is 42 at high idle no load. 32 under load......Falling to 20 for a few seconds is pretty well normal for most. Quit guessing and put a restriction gauge between the lift pump and water separator. 0-2 is sucking air. 3-6 or so is normal. A little higher is doable 9-10 is a restriction

 

How does the turbo look? No exhaust leaks at manifold or turbo mounting?

Is that roughly where your EGT's were before, or a little higher?