Loss of fuel MPG over time, what's the possible causes???

[JohnFire]

Ok I have been curious as to the reason my truck has lost mpg over the years. When I was in Germany and I first bought the M1009 in 1999 I was getting around 15mpg till I changed the air filter Then I was getting around 20 mpg at around 70+mph running on the autobahn. The truck was still pretty much stock. After my last military deployment the mileage dropped to about 15-16mpg. The guys said they kept starting and running it for me while I was gone. Since I have been back in the states my truck had been around 15-16mpg. I have since had a banks turbo installed. I am still only getting 15-17mpg. The best I have gotten since I have been in the states with the turbo is 20-22mpg, but I had to keep it at 55-60 mph and on a highway that just doesn't work well. Well I am curious to hear what ideas you guys have. I change oil and fuel filter regularly, and clean the K&N frequently. The only thing I have thought of is the IP.

 

[ida34]

RE: Loss of fuel MPG over time, what

How many miles on the engine? I would guess injection pump.

 

[JohnFire]

RE: Loss of fuel MPG over time, what

I am at 63,000 and the first loss of mileage was probably around at 40,000. I bought it at 22,000 miles.

 

[ygmir]

RE: Loss of fuel MPG over time, what

I've noticed with all my diesel cars, trucks, and tractors, a gradual decrease in economy since the newer fuels have come out....

 

[WillWagner]

RE: Loss of fuel MPG over time, what

Does it smoke black more than normal when you accelerate?

 

[JohnFire]

RE: Loss of fuel MPG over time, what

It pours out when I push my foot all the way to the floor. I keep joking that it is like the spy hunter video game smoke screen . I am not sure at regular speeds I don't think so.

 

[WillWagner]

RE: Loss of fuel MPG over time, what

Black smoke is wasted fuel....not enough air to completely combust the fuel being put into the cylinder. Was it after you put the Banks kit on that the mileage went in the toilet? I agree with ygmir, When the switch from lsd to ulsd, I noticed about a 1 mpg loss in mileage. Did you put the Banks kit on or did someone else do it for you?

 

[JohnFire]

RE: Loss of fuel MPG over time, what

The initial loss came before I put the banks on back when I was stationed in Germany. I have had the banks on for about 2 1/2 years and it was installed by a diesel engine shop. I had a slight gain, but never back to what I had been getting. I will probably do up an excel sheet on my mpg, since I have been tracking the mileage on my truck since about 2000. Would bad injectors cause this too?

 

[Blood_of_Tyrants]

RE: Loss of fuel MPG over time, what

It sounds like your injectors are not atomizing the fuel very well. This could be just age and wear or maybe they are clogged.

 

[WillWagner]

RE: Loss of fuel MPG over time, what

Cheapest things first. If it is getting full throttle. Try nozzles.

 

[JohnFire]

RE: Loss of fuel MPG over time, what

anything special I should ask for when getting the nozzles? I am one for efficiency not high performance if it costs me mpg.

 

[CCATLETT1984]

RE: Loss of fuel MPG over time, what

ask for the 6.2L nozzles for the injectors, also have them set the pop pressure to the upper end of the normal range, I dont recall what the stock pressure is, but a slightly higher pressure will atomize the fuel better.

 

[Refalgren]

RE: Loss of fuel MPG over time, what

Related Question: When I start up my M1008 in the mornings, I wait a good 60-90 after turning the key halfway before I start the engine. However Upon starting, I have to wait at least 2 minutes before the White Smoke starts to go away. Is that normal? Also Occasionally when I start the truck, it turns over, runs for a few seconds, then sputters out. At which point I have to turn the engine over 3-4 times before it wants to start again. After it starts, it runs very rough at low idle until it warms up. Any clues?