fuel economy dropping. help!

[m1garand_man]

I have an 86 m1009 w/ 96k on the odometer. I've had it since 87k and made the mistake of running diesel clean through it a few times to see if I could clean it out and get it to do 20mpg . its progressivly gone from getting 18.5mpg freeway to 15.3mpg. whats going on? I changed the mechanical fuel lift pump because it started leaking. I changed out all the rubber lines for the same reason. it has a new fuel and air filter and new injectors. what can I do to bring it back up? will I have to change the injection pump? the scribe mark on the pump is lined up with the mark on the timing housing so the timing should be good. I dont want to change it and not have any improvement. I changed the injectors because it was in the mileage where its reccomended to do and it didnt help with the economy. please help

 

[4bogginchevys]

I noticed your west of me a couple hundred miles, have you considered the possibility of winter blend diesel? I know it's not as cold near the coast as it is here, but snoqualmie pass is close enough to make it possible that diesels in your area need it. I got my 1008 just before winter and immediately noticed a change in mileage in just a couple weeks as it began to get colder.....if it runs....dont do the IP, just wait it out for a little while, if there's a real problem killing your mileage it will show itself soon enough. good luck

Edit: like B.B. said, colder also means longer high idle times, and if you wait on the idle to kick down before you go it'll soak up the fuel.

 

[southdave]

what the teenager driving around ? lol

 

[T_F_E]

Biggest effect on mileage for me is my right foot. Rolling coal at every stop can kill your mileage fast.

 

[4bogginchevys]

Biggest effect on mileage for me is my right foot. Rolling coal at every stop can kill your mileage fast.

Ya, what he said...

 

[T_F_E]

Also I have never had a problem with diesel clean.

 

[Billy Bobbed]

It might be the cold.The colder it is the more fuel.The more fuel instead of air.Its like having the choke on longer.