Chubbz

85 Ford F-150 4x4 300 straight 6 4 speed base model. No rear tank. All stock except for the stereo and tool box.


I got the truck about a year ago. So I finally come here looking for help. I've tinkered on cars and trucks for awhile. Nothing major though just belts and crud like that.


The problem I'm having now is the gas mileage. I'm not sure if it's right or what. Been getting about 12.5mpg. I do mostly highway driving keeping the speed at 63mph or less but have drove in the city for a tank and got almost the same.
Carb was cleaned and adjusted.


Any ideas?

GhostriderI

Sorry I missed some of your earlier posts. That sounds close to right (I can get about 15 on a good day), a little on the low side, but close. You can check for vacuum leaks, make sure your clutch is adjusted correctly, and make sure you do not have a brake dragging/sticking. When was the last tune up (plugs, cap, rotor, and wires)? How clean is the air filter? Double check your fluids (transmission, gearbox, and differentials).

Hope this helps

Chris_1

iTrader: (1)

Tire pressure can rob mileage too. Slightly higher pressure for the highway helps it roll easier. A little bumpier around town though.

Chubbz

Tune up was about 3 months ago. Same with the filter and fluids. Does the O2 sensor really make a difference?

burnthelight88

Shouldn't have an O2 sensor on a carbed truck that I'm aware of. Could be wrong though.

GhostriderI

There is one installed, it just monitors the exhaust to warn if a to rich/lean mix by turning on the emission check light. Mine has been in-op/plugged for several years and I have not seen any difference in performance.

Chubbz

I did O2 sensors in a newer car and it made a pretty big difference of about 4mpg.

burnthelight88

Yeah in a newer car with EFI it makes a huge difference. This is a carburetor. Ok didn't realize you had an emissions light in 85. It won't affect gas mileage though.

1967 Tempest

Yeah, I changed mine on the 86, but it made no difference. I will say that I have been ready up on the feedback carbs when I bought the truck 2+ years ago.

They did say that if the ECU sees a lean condition, even if it isnt, it can dump fuel in to not knock.

I would get the scan tool and see what it says on all of the test.

KOEO key on engine off

KOER Key ON Engine running.

I am not sure if your 85 is the same OBD 1 as the 86, but my Equus 3145 says it works for 82 to 95. I can sell you mine for cheap. I paid close to $40 with shipping. Ill sell you mine for $20.00 total. I used it twice. I got a different scanner that does both OBD I and OBDII.

I get closer to 20MPG with 31"s in the rear.

Chubbz

Thanks for the offer but a friend has one that I can use for free. Tires are 235/75r15 all the way around. Still on the factory rims with factory caps. Looks like the top end had some work on it but can't verify. Only things wrong are gas mileage and body rust.