At some point yesterday I lost boost some of my boost, smoke, and the truck dosent pull as hard. It ususally boosts 50psi and can fog out a 4 lane road and pulls hard up to 3000k rpm. Yesterday afternoon it started only boosting around 32psi. only puffs a small cloud if I really stab it and dosent pull as hard. I'm thinking because of the lack of smoke its AFC related and either the little tube from the head to the AFC housing or the diaphram inside the housing tore. What does everyone else think?
Thanks
Chris

The tube "looks" ok

 

I've run into 6 ruptured diaphragms in the last 12 years.
It does happen, but the drop in power is very noticeable.
Don't think it's your problem.

 

The drop in accerlating at high RPM and almost no smoke compaired to befor is what makes me think the AFC rack is not moving forword very far anymore. If it was moving forword and the boost leak was say at the turbo (30psi is still way more then needed to move that rack) then the truck should be smokeing even worse because the turbo isnt forcing enough air to clean it up... not that it ever really did clean up.

 

well took it apart. Diaphram seems ok. Slid the #10 plate back about 1/16 of an inch while I was in there. Also replaced the tube that goes from the head to the AFC housing, a tube I made up with compression fittings from home depot, back to the original tube. I noticed a small tear in the fiber type gasket on top of the heating grid. Anyway took the truck for a run and its worse now. Down to 20psi and it wont rev above 3000. Used to pull pretty hard to 3400. any ideas? its deffintly not getting fuel. Feels like when I used to have a valet switch. Thats why I started with the AFC housing.

 

And your fuel pressure is, what???

 

And your fuel pressure is, what???

 

not sure what my fuel pressure is. But that stuff is all new from when my truck was giving me crap a couple months ago. (turned out to be a bad fuel cam plate) new lift pump, new filter, cleaned the heater screen, new short hose under the block there.

 

Your shut-down solenoid may not be lifting all the way???

Waylan

 

checked that one I think. I wathced it when someone started the truck. It shot up pretty high and while the truck was running I couldnt lift it any higher. I also noticed today that if I flog it the boost spikes to say 22psi (used to hit like 50-55) then drops and holds at like 15-17. so maybe it is fuel pressure? the lift pump and fuel filter are new a few months ago. maybe have 3-4000 miles on them. any ideas where to start?

 

The solenoid is up all the way if you can't lift it any higher. If that is good, I would change the fuel filter again...........one bad tank of fuel will stop a filter up quick. Also, a little water in the fuel can swell the filter media as well.

Waylan

 

change the overflow valve??? maybe its somehow stuck open??

 

oh yeah that was brand new too when I changed everything else. however it wasnt the cuplret at the time so I do have the original if I need to try it. Good call there.

Thanks for the fuel filter tips too. Im going to try that this weekend.