Hello all I have 98.5 3/4 ton 5spd 2wd with 204k on it and its only getting 13mpg in town with me taking it easy on the throttle (I try to see as little black smoke as possible). I live in town right now and drive about 15 miles a day to work and class. I have put on a 4 inch exhaust, K&N intake and Van Aaken smart box. Am I asking too much of the truck or is there some room for improvement?

 

How about a lift pump, and a fuel pressure gauge? You can demand all the fuel you want from your injection pump, but if the supply isn't there it will only damage it.

 

I was told it had a new lift pump and injector pump at 130k and it was factory replacements, I do not have a fuel pressure gauge. It does seem to lag a bit when I do need to get on the throttle.

 

Could be a multitude of things. Have you scanned it for codes?

Knowing fuel pressure, and keeping it correct, is the #1 way to avoid a $1000+ bill for a new injection pump. It will also promote fuel economy and performance.

 

Also how about your valves have you ever done thim? there suppose to be done at 130K on schdual a and 150K on Schedual B Help with throttle response too. But RAWilliams is right to .
I did my valves when I got it and ther were way off!! that was a 212K helped my milage alot.

 

I'd check for codes and get a fuel pressure gauge on there asap.

 

Nozzles would prob help too

 

I have never had the valves adjusted so it sounds like it is way past due. Where can I have my codes checked, anywhere or a shop that specializes in diesel performance?

Is this what you mean by new nozzles?
98502NOZZ50 DDP Dynomite Diesel Performance Cummins Injector Nozzles

 

Yep, those are nozzles.

Most large chain automotive store will code check for free. Code readers can be as cheap as $10. Not a bad idea to get one and keep it in the truck.

 

I see thanks everybody for the quick reply's and sorry if my questions are basic I'm just now getting into this stuff.