Hey folks; need to find some answers, for the last 2 weeks the engine light has been coming on and off. Truck has either been doggy with black smoke and poor acceleration or just driving along and the light comes on. I took my 1998 6.5 into have the codes read and it came up with P0101 maf system performance and P0236 turbo charger boost sensor A circuit range performance and P0251 Inj. pump fuel metering control "A" malfunction cam/rotor/injector.
Can anyone tell me where to start to find and solve these problems?
Thanks
Darcy

With a combination of boost and EGT codes, look first into your vacuum system. That is a common thread between the two.

Fuel metering doesn't sound good... checkout diagnostic checklist and rule out all the simple stuff first.

Check vac lines from pump to waste gate for leaking also check to see if waste gate is moving.

Howdy MB,

Welcome to the site, look over the troubleshooting guide linked in mine & KNKREB's signatures, also read though the welcome notes which will give info on how to update your signature with basic info needed to better assist you.

It does look to be a vac related issue, if you don't have one, get a inexpensive vac/press diagnostic gauge from autozone or another part store, check for vac from your pump all way back to solenoids, either you have a leak or bad solenoid form the initial info you have relayed to us. Post back what you find.

Hey everyone;
Thanks for the response and sorry for not giving you all the info. The truck is a 1998 1500 6.5 turbo, auto trans. with 200,000 kms on it and only 40,000 kms on the new injection and lift pump. I have checked the waste gate and it seems to be working ok and I put a clamp on the vacum line leading to it. My next question is what do I check with the portable vacum pump? Also when the truck is cold it has more pep and is more responsive with no black smoke and after it is warm thats when the problems start. I also notice that when it is warm the vacum pump is very noisy [you can hear it working] and it does not shift very well.
Thanks
mb gmc

Darcy that info needs to be in your signature so you won't have to repost it, see how in the welcome notes.

Still sounds like WG issue, probably a WG solenoid on it's way out works when cold but not when underhood heat is getting to it. You will need to check vac while driving, with a gauge in cab you can watch, you may need a piece of 1/8" rubber hose added to make it reach and a tee to gauge and actuator, check main vacuum and vac to the WG actuator while driving. make sure to not pinch the hose as that will deadhead your reading