10 replies to this topic

[sad209]

I have a 1985 F-150 XLT and am getting 9 mpg on my fuel mileage. This can't be normal.

I am attempting to find a replacement heat riser to possibly combat the problem.

Does anyone else have any ideas?

Shawn

[Justshootme84]

Assuming it has a carburetor (not fuel injection), you can cover the basics, like tune-up, PCV, fuel filter and air filter. A K&N filter may help get up to 1 mpg more. I don't know how much the heat riser actually helps, but I believe the stock air cleaner housing is very restrictive, and an open element air cleaner may help, too, if allowed. Overhauling the carb and using a rebuild kit with new gaskets may help if the carb is at fault, like it's running too rich. 10-12 mpg is about normal, and it helps to keep your right foot off the floor. The harder you drive the Bronco, the less the gas mileage will be.

[Ktomek06]

Totally agree randy,
You might also wanna check out some aftermarket mods to help mpg. Exhaust Mods, FIPK, Air Filter, etc.

[Shadow_D]

I swear by full synthetic oils, motor, tranny, F & R diffs and Transfer case. If you have any leaks DO NOT USE SYNTHETIC OIL!
Also you can try using a higher octane fuel. I was only putting 87 octane in my 90 and was only able to get 8.5 - 9.3 MPG. I started to use the higher octane and my mileage went up to 10 - 10.5 MPG. and that is without using synthetic oils (I am changing everything over on Monday) so I will let you know what the difference is.

[sad209]

A few more details:

I am running a 1985 F-150 XLT, with a 351, and a two barrel Motorcraft carb.

I was hoping to be able to put a Holley Throttle Body Injection kit on it, but I don't know if there is one that will work on my truck since it is a semi-computerized.

I guess my biggest question is what is the best order to do do things in to improve my gas mileage? I already need a new exhaust system, so that is somewhere at the top of the list.

10 to 12 mpg is not the best it can do is it? Can't get towards 15?

I am in California so most mods have MANY restrictions...

[Justshootme84]

Other states are now doing smog testing (including some places here in Texas), so you do have to be aware of what mods you can do, what parts are C.A.R.B. exempt or approved, and so on. With the stock 2-bbl, you should around get 8-10 mpg city, 12-15 mpg highway. The Bronco weighs nearly 6000 pounds, and even the 351W is low on HP (139HP for the 1985). You will get the best mileage with a properly-tuned engine, so that's where I focus most of my work. Regular tune-ups, filter changes, fluids, etc. are essential. A minor vacuum leak, misfire or electrical problem all rob you of power and mileage. If you modify the engine for more power, start with the exhaust system. Many older trucks have clogged catalytic converters, and much of the emissions equipment is not working. My approach has been to keep as much of the pollution control as feasible, both for cleaner air and passing inspection. I have repaired most of the original items, even some that are discontinued. I don't advise removing all of the emissions stuff and the cats, but am pleased with the Flowmaster muffler.

Whew, I'm winded!!! New exhaust, engine tuning, good driving habits to get best mileage.

[Seabronc]

What size tires are you running? What is the gear ratio for your rearend? There is a a great "gas milage vs performance chart" in the 80's Bronco parts catalog on the Bronco Graveyard site. You might want to look at it. Also, don't forget that if you change tire diameter size you need to change the speedo gear to accurately display speed and milage. You probably aren't going to get 15, but every litter bit counts.

[sweepersrgr8]

Belive it or not...The 2 BBL carb is hurting you also. The primaries on a 4 BBL carb are smaller, therefore you use less gas. This happened to me on a '79 truck I had, Nothing but an intake , and Holley 600 increased fuel milage by 6 miles per gallon.

I now drive a '89 EB Bronco, and around town 10-12 MPG is normal. On the interstate 15 is possible.

These trucks are gas hogs. Why do you think they come with a 33 gallon tank?

[dicain]

first things first your truck weights more than 5000lbs plus gear.
Not to mention has the aerodynamics of a brick add nobby tire and we have a eco nuts worst nigtmare. all you can do is keep the engine and suspension in good condition.
oh yeah, if your like me and like to here the roar. Gas milage is not going to happen.