MPG decrease

[emceescottyp]

In 2009 I had new 50hp over stock injectors put in my truck and was getting 17-18 mpg in my 2001 Silverado 2500 HD 4wd crew cab truck. in 2011 had to have the head replaced on one side of the truck, when I got my truck back it only gets 10 mpg!Tthe other head/injectors were replaced this year with no change still getting 10mpg, anyone know what would cause this?

[More Power]

Welcome to the board!

For most Duramax powered pickups, 10-mpg means the owner is using his truck to tow a 15K-lb travel trailer at legal interstate speeds.

I honestly don't know how it's possible for an otherwise healthy empty non-towing truck driven at legal interstate speeds to get just 10-mpg.

I talked to a diesel owner a few years ago who was terribly disappointed with the 13-mpg he was getting with his 3500 dually. It took about 10 minutes of discussing fuel economy before he admitted that he had a 3000-lb welder permanently mounted on the flatbed and that he drove 85-mph between jobs in the oil field. Once I heard that I congratulated him on the great fuel economy his truck was getting.

Moral of the story....It helps to offer more details about what modifications have been made to the truck, how fast you drive or mention more about how the truck is used. Let us know more. Jim

[Kennedy]

Opening up an LB7 to do head gaskets exposes the injectors to all kinds of possible issues. If a well meaning tech uses mechanical means to clean the carbon off the nozzle tips this can cause real issues.

Additionally, considerable rust can get into the injector inlets when doing the R&R and while it's possible to flush the junk out, reinstalling the old lines buts junk right back in.

Imbalanced injectors seem to have a pretty dramatic effect on fuel economy and performance. What confuses people is that the typical "balance rates" at idle appear to be just fine, but that is simply low pressure, low rate where the high pressure, and moderate to high rates tend to cause grief likely due to atomization or spray pattern deficiencies. That or simply restricted flow.