I have a 1986 F150 with a 4.9 l 300 inline 6 with a three speed automatic C6 transmission and I am getting 9.5 mpg. The odometer reads 41,XXX but has no hundred thousand place. I have replaced the spark plugs and spark plug wires and replaced the computer controlled distributor with a hei vacuum advance distributor. I have also replaced the gas tank and engine mounted fuel pump. It have a single barrel manual carburetor that was brand new but had rusty gas ran through it and had to be rebuilt. I does run pretty good but just gets horrible gas mileage. I read that Ford claimed this engine got between 20-30 mpg when new with an overdrive manual transmission in the early 1980s. Is there any way to get better gas mileage out of this truck.
That a great motor, unfortunately in the auto trans it got lot less, may be a set up with a towing rear. Check specks. The stick overdrive did get good mileage, on a good day 28. Around town 18. Bump up tire pressure a bit. Drive slower, average should be around 17 mpg. May be other issues though, and they were real bad in. Hill country. Big pistons love fuel
