I have a 98', 4x4, ctd, q-cab, longbed, 3.55 rear and the F.A.S.S Fuel System. The truck now has 77,000 mile on it. Replaced lift pump and injection pump in the past year and new tires and brakes. Tried appps reset and clean the map and iat. I also change fuel filter every other oil change and clean air filter too.

My truck only gets 14.5 mpg. I heard that injectors could leak and cause poor mpg. As far as I know the injectors have never been replaced. Can they leak? Is there a test that I can do?


Thanks

 

I had a injection line leak at the point where it entered the head. Never heard of an injector leaking.

Do you use an injector cleaner like Howes, Power Service or Lucas. I do almost every time.

I did not notice a big difference in performance when installing injectors until I add the BD box. Just adding the box will increase your mpg - if you keep your foot out of it.

You can do one or the other - but not both if you have the auto. If you do both a tranny upgraded is needed.

 

I read this in a Haynes Repair Manual, under injectors. "A leaking fuel injector could cause several syptoms depend on the severity of the leak. Fuel knock, poor acceleration and performance and low fuel economy." It goes on to say that a defective needle valve operation may cause engine misfire.
Engine runs fine, smooth idle and great power ect. Just low mpg. The first 18 months I had the truck, I got 16.5 mpg now I get 14 to 14.5 mpg
I want to do one more engine upgrade but I want something that will help mpg. Sounds like the box maybe the way to go.


Thanks

 

Two months ago I clean the IAT sensor no change and about 30 days a go I replaced it.
I also thought maybe it was the fuel, (summer/winter blend) that is why I took so long ask. I get my fuel at the same place all the time, except the last 3 times, no change.
Not sure about using an additive in the fuel.

 

In that case, I think I will leave the injectors alone, because the truck really is running great.

I just had the diffs and tranny fluids change 3 months ago and new tires 4 weeks ago and check pressure monthly. Maybe I will look into synthetics on the next fluid change.

Thanks for the ideas

 

What else could possible need repairing? Any suggestions would be appreciated

 

I just bought new tires 265/75 R 16. I have not yet looked in the door panel yet but I don't think there too big. Boise is a nice city, like to move there. When the tires were put on, the shop tech notice my brakes showed signs of heat crakes, maybe they were hanging up a little. I installed new front brakes last weekend.

 

It seems that the sticker on the door panel says 245. Could that make a differance in mpg? How about my speed and rpm's? Also, this maybe a silly question, but will I rack up more miles or less miles on the odometer or is it taped into the trans.
THANKS