for a 318 and 2wd 15mpg isn't really excellent.

 

What is average, good?

 

Does the "Plenum" and "Death Flash" affect 6 cly too?

 

Ok, I just got back from 3 days on the road, 99% highway, cruisin at 110 kph (65 mph) and I got great mileage!! I ran Lucas fuel injector cleaner every 2nd tank for 6 tanks, Then I left on this trip. I started tracking my mpg, it was consistent at.......18.29 mpg (US gallon) and 21.9 mpg (Canadian gallon) !! I am VERY PLEASED!
The truck always ran very good and had lots of power, but this is the best mpg I have had! Now to be fair, I've only had the truck for about 8000 kms (4800 miles) and just did the 2nd oil change on it before I left on this trip. I was gettin 25-26 mpg from my 97 F150 4.2L V6, O/D auto and was disappointed with my initial mpg's of 15-16 p/US gallon . I have tuned it up, replaced the air filter and replaced the muffler with a Flowmaster 40 .
I had hoped I could get 20 mpg out of my Ram , but after reading about the 12-13 mpg on here I was ok with my 15-16 mpg, but 18+mpg is great!

 

reading on what you guys have said on here im starting to think that my plenum gaskets toast on my 318. on a good day in the city i get maybe 9-10 mpgs but if i take it out of O/D i seem to get 10-11 somehow which doesnt make much since to me. ive replaced the plugs and wires once and have been to a few places in the city and no one can tell me if theres a fuel filter on my truck as well.

 

Yes, the 3.9L V6 has a very similar plenum gasket design that is also known to have this issue.

 

The fuel filter is part of the fuel pump module, it's built in with the pressure regulator.

 

I get 10 mpg with my 5.9 in my Jeep. And it only weighs 4200 pounds. I was hoping for better. Bleh.