Nwe IP, New Injectors, Bad Mileage

[Doc]

I installed a reman IP, new injectors, and a new electric fuel pump last week. Timing is set, idle is set and Big Red runs like a new truck. There are no more starting issues, no smoke at all, less pump noise, and no leaks anywhere. Oh, and 3.55 rear gears instead of 4.10s.

So why would I only get 147 miles out of a full rear tank?
Is there a break in period for the IP or injectors? Or did I fail to do something when installing the new parts?

With a bad pump and worn out injectors I consistently got 200 - 210 miles out of my rear tank. I don't get it.

 

[tuckerd1]

Heavy Foot???!!!

Testing that new feeling again!!!

 

[Doc]

No. As a matter of fact, I've been taking it easy. Before the new IP and all, I had to get on it pretty hard to get onto the freeway, but not now.

 

[tuckerd1]

Well, timing can affect the mileage. Was it timing with a light or by sound and feel?

 

[Doc]

With a computer and a light. The place I got the pump from timed it for me. I need to add, I get no smoke at all. Even if I get on it to get on the freeway. In the morning I get a tiny puff of smoke when I fire the truck up, but that's it.

Does the computer need to be reset after installing the new parts?

 

[tuckerd1]

Does the computer need to be reset after installing the new parts?

Only "computer" on these trucks is for those which have an E40D transmission.

 

[Agnem]

Almost sounds like you have a leak and your pouring it out on the road somewhere. Your oil level normal?

 

[Doc]

Everything seems perfectly normal. Absolutely no leaks, no oil burning, nothing. The truck runs better than it has in a long time. It idles smooth and quiter than before. It starts within 2 seconds, it's running great. I just thought I'd get better mileage with a new pump, lower rpms from the 3.55s, and new injectors.

 

[SKimballC]

Watch the mileage over the next couple tanks, one tank is not enough to tell you for sure. I keep hearing gripes lately about winter blend fuel killing mileage. I know that mines dropped a couple mpg since it got cold so I guess that might be why.

 

[Snowdiver]

Maybe someone siphoned some of your fuel?

 

[Doc]

I don't know if we get winter blend fuel down here in San Antonio, but you never know. I'm gonna watch things for a bit and see how it goes. I'll also call the place I got the pump from and see what they have to say.

Big Red is my only form of transportation so I burn up a good bit of fuel everyday. If my mileage doesn't get better soon, Big Red gonna be put in line at the auction house. I'm tired of have to spend my weekends keeping the truck on the road.

 

[Diesel JD]

Hey man...are you sure the tank is really empty, or are you just showing empty on the gauge? This could be important.

 

[OkieGringo]

When you changed out the diff gears, did you change the speedo "driven gear" on trans or have the speedo recalibrated? Is the FSV returning unused fuel to the tank being used? My FSV is stuck and only returns to the rear tank. Maybe yours is returning to the front tank. OkieGringo

 

[Doc]

Good point. I guess I could run it a bit longer, but I'd hate to run it dry. I'm gonna give it a bit more time and calculate the mileage.

 

[Agnem]

Did you get your timing set precisely?