3406b low boost and fuel pressure issues

Go looking for why it’s not moving freely. I can’t be 100 percent but I’d bet my shorts you found your issue

 

Oil pressure has a role as well as spring pressure. The servo hooks on back of rack bar at the nail head. It moves the rack. The plunger scroll gears are driven by the rack bar. So it could be a sticking plunger, weak springs, bar sticking in bushings....etc. it’s time to reman the pump basically unless you can fix it yourself

 

Remind us what your expectations of boost should be?

I have seen B models that made 36 I have also seen one that would run off and hide from them making 27. Without rack setting, and timing verification it’s a slippery slope

 

Yes one is longer than the other though believe it or not I’m drawing a blank on which one. Just check to make sure you have .030 spring pressure. I can’t see those moving at any rate. And it takes a big leak to take 7 psi of boost I mean a huge leak so that leaves turbo, fuel, or timing. Surely if the timing had slipped that much you would know by sound, it would rattle its tail off. Though the hyd return advances like the 4MG and up use will go full advanced just about when the clip comes off. But again you should hear that almost no missing it.

 

Something must have been messed with. As delivered my 2EK 425’s put up 22psi and the 3ZJ C’s we’re around 24psi if I remember right. All of them 2100 rate Brakesaver engines. I’m not a fan of mystery pumps. Alway got a little sick feeling getting one with the seals gone off it. Most people should just leave those ####ing screws alone.

 

I've seen 2 different Cats with windowed blocks from guys screwing with them. Back in the 55 era when a lot of trucks were spec'd gearbound, so they'd turn the screw for more rpm.

To their credit, both motors were still running with the rod flopping around. Kinda cool to see, but a bit expensive.