I have a 97 2500 12 valve with KN cold air intake ,aftermarket 125 hp BD fuel plate ,govern springs changed to 3200 rpm. I just got new pyro and boost gauges but have not installed them yet trying to still figure out how to. All of the sudden the other day it started to stop pulling at 1500rpm all the way up under load. but without load it tacks out no problem.Before this started happening i was getting great smoke and power but now i only have the smoke and power to 1500 after that no smoke and power lacks. I have been looking for a blown hose to the intercooler or to the intake and am leaning towards that ..my next step is to take all the hoses off and inspect closer and reinstall with dioelectric grease to seal ..i have noticed a slight hiss near the turbo side of the intercooler intake and why i am starting there thinking i just am not seeing a hole with them on.. i hooked up the code reader today as well and no codes... any suggestions would be welcomed...

 

dont grease the tubes! they will blow off, it doesnt sound like a boost leak, when was the last time the fuel filter was changed? the lift pump could also be failing, the best thing would be to get a fuel pressure reading at the injection pump inlet

 

Thanks so much for the reply Dodgetrucker my buddy and i today did a bunch of things pretty much starting on the drivers side of the motor cleaned the prefilter as well as changed the main fuel filter and installed the boost gauge..prefilter was pretty dirty but the main filter was good it was changed a month ago but changed it anyhow while it was apart.Cleaned and checked all the tubes from the intercooler to the intake as well as the intake while i had it off to install the boost gauge(did not grease tubes as u suggested.It is with no load hitting 18-20lbs of boost @3000rpm as well i did a run up a 8% grade long hill here and in 5th gear (Manual Trans) throttle wide open all i could get was 18lbs of boost @1900 Rpm..It is still not pulling the way it use to not sure what the boost should be but the truck feels like it is laying down. Tomorrow we are pulling all the tubes off the passenger side to inspect as well going to air up from turbo outlet through to the intake to see if we can find a leak that way my buddy and i are both thinking leak as well at this point but also realize we are going to have to check the fuel pressure as well.We also did a little test of rpm2000 then snapping to 3000 with my buddy feeling the wastegate rod feeling for movement but nothing so we might do a air test on that as well tomottow ..i will watch here close if u have any other suggestions that i should do and thanks so much it is great to be able to talk to a veteran 12valve guy ...i just can't bring myself to ever getting rid of this old 12 valve so i am going to just learn all i can and keep making it a better truck diffs are all done body and paint next summer..

 

the boost pressure is normal, they are set around 17-18psi from the factory, the only real way to change it is to ues a "boost elbow" or plug the waste gate hose, but you will not have any wastegate movement under no load situations, actually it probably wont move untill about 15 psi or so, if you are not having black smoke under the power loss situation, then the turbo system should be ok, get a look at the fuel pressure under load, the lift pump could be failing, or sucking air, and the overflow valve could also be weak, if you do find low pressure, pinch the return line while running, if the pressure increases, replace the overflow valve, if it doesnt increase, look at the pump and/or fuel lines from the tank

 

Thanks Dodgetrucker with what u have said in mind i will bail on the boost leak issue and stay on looking for a fuel issue with the lift pump and other things u mentioned today i only have today to figure it out or it will have to wait for 7days while i work my next 7 days 12hrs a day those are my job hrs normally..but i will update tonight as how far i got ...again thanks so much for your help...

 

Well it rained pretty much all day so did not do anything today so it will be a week before i get to it now..but i will update when i do the other thing i realized is i don't have a fitting for the fuel pump to deal with the banjo so i am ordering a new fuel guage as well that way i don't have to ever wonder again ..see ya next week

 

Thanks dodgetrucker75 for all your help one of the lines from the prefilter was restricted ..as well i am sure it strained the lift pump so i replaced both as well as the overflow valve just for giggles ..all is well now ...i am still not sure if the wastegate is sealing all the way when closed so when i get time i am going to have a look at that as well because i am pulling the turbo anyhow installing the pyro ...but thanks again for all your help ...

 

no porblem bud, glad i could help