ok i love my new truck but the gas mileage is killing my wallet. im averaging about 8.5 to 9.5 miles per gallon depending upon my lead foot, 9.5 being grannying it. i drive on average 80miles a day and its costing me $25 every other day. now i know the carb needs to be tuned since the new control module, before it would average 10mpg grannying it, not that much better. its a new motor and runs strong. i think the problem lies in the driveline. its a c6, and at 60mph the tach is at like 2800rpms. the tires are 265 75r16. i dont know the rear end ratio havent looked at it yet, anyone know what it might be? 85 f250 lariat 4wd. i also cant stand to drive the thing on the highway, as going 70mph requires like 3100rpms and probable 5mpg. is there any transmission that i can swap in here that has overdrive and is as stong or almost as strong as a c6? is there something else really wrong with the truck being that it gets 9mpg? like driveline drag or something or is this normal being its a 3 speed. i would think that with the new motor, and performance parts like exhaust intake carb, it would get better mileage than stock. it would help to hear from ppl who have increased their mileage and what they changed. anyway thanks for listening to my rambling and trying to answer my questions.

 

a 4.10 gear ratio would give you around 2700 rpm @ 60mph
i would tune the carb first
no overdrive tranny is as strong as a c6 unless it is built $$$
if you put 3.73 gears in your 60mph rpm would be 2400
at 70mph your rpm would be 2850
are your brakes dragging?
are you still running the stock tfi/eec4 ignition? your comp may shot, wiring damaged
i have the 3.73 gears and a stock 134k 351w and i pull around 12-13mpg

 

buy an escort save the truck for weekends

 

Well, you said it is a new engine, it could just be tight. After it breaks in a little more it may go back up to 10.

 

ok ill get the carb tuned i guess and start from there.
i know the c6 is the strongest, just wanted to know what options i have for overdrive trannies that will work with my combination.
i dont think the brakes are dragging they are fairly new, maybe 5k miles on them.
computer was just replaced hense why the tune isnt perfect like it was before, still a good tune but not perfect.
im guessing i have at least 4:10s.
i dont see how my speedometer can be off then given the tires arent that much different, when i drive by those speed checker things its always 5mph lower than what my guage says, not sure if this is an accurate way to measure it but makes me wonder anyway.
dang if i can pull off 12mpg on this rig ill be more than happy.
anyone suggest where i should get the carb tuned in SE michigan for cheap?

 

the motor should be broken in already, i would say over 5k miles. doubt it would affect mpg anyway.

 

im not buying an escort, lol, i got the truck as a winter car, i have a 98 ss camaro to drive on the weekend and to get good mileage(sucker averages 24mpg and has over 450hp). just driving the truck in the crappy weather and want to save some money on gas.

 

I don't know what you're expecting....this is a 3/4 ton truck and 4 X 4 also.
The last thing this truck was designed for was good mileage. Sell it.

 

lol no, im expecting at least 10mpg. just looking at ideas to get better mileage not saying i dont want the truck cuz the mileage sucks, im used to gas guzzling cars.

 

whatever you do, dont get an escort, hehe

 

hourang....i average about the same mileage u do...mine's an 84 f-150 4x4 300-6, t-18 4 spd w/ 3.55's and 30x9.50's....the biggest difference lies in the miles our trucks have...your engine is brand new, mine might as well not have piston rings left...lol...i've got a little over 300,000 on this engine, if it's the original engine...she burns gas and oil about the same....if i put oil in every day, i put in about a quart a day...thankfully, i don't have the drive that you have every day....tho where i live, it's easy to put 80 or 100 miles on in a day just with a little time to waste...lol....i'm actually considering getting a smaller newer pick-up, or a little economy car for my errand running, and build my truck how i want it in my spare time so i can have it for the weekends and hunting season....

MontanaFord

 

yeah i would say your motor needs a rebuild, lol.

guys, im NOT getting another car, the insurance is killing me as it is. i love this truck and just want to hear any advise on how to increase the mileage. im getting like 8.5mpg everytime, im sorry that just cant be right with the new motor and performance mods it should get better than stock gas mileage(unless you get on the gas of course which im not). the tune is not perfect with the fuel mixture but it purrs like a kitten and runs strong, no hesitating, starts right up, etc. thanks 84-250 for your help. anyone that has increased their gas mileage in some way plz tell me what you did.

 

if your still running the tfi/eec4 computer system, i would make sure that it works. when my computer went out, i was getting positive voltage on the ground wires by all the sensors. i was also getting positive voltage on the feedback wire that goes from each sensor to the computer.
the only thing that worked on mine was the ignition advance.
i gained a few mpg from converting to a duraspark2 system.
what engine mods are you running?

 

ok yeah, like i said the computer is brand new, maybe 1k miles on it, is there anything else in the computer system that could be bad? i havent looked at all the differences between the ignition systems but a few mpg from an ignition upgrade might be worth it, can you give me more info on that. guess ill do a search and read more about it. its got long tubes, dual flows, no cats, edelbrock intake, holley 650 4barrel, and a new long block bored .30 over.

 

If your turning 2700 rpms at 60mph, I don't think you are going to get over 10 with a carb setup. Carb rebuild will probably help a little. I messed around ($$$) with my 85 f150 351w ho, c6/3.00 rears, new edelbrock carb and intake, trying to get better than 12mpg on the highway and I just can't do it. I'm turining around 2100-2200 rpms @ 60mph. I was told this before and beleive it now that the mid eighties trucks with the carbed 302's and 351's weren't really made for fuel efficiency but more for power.

I gave up and bought a 96 f150 with a 5.0 efi and am in the process of selling my old one. Shame, I dumped a lot of money in my old one and it's a great truck, but all my family lives at a minimum of 2 hrs away and I'm constantly going back to help on the farm or to my hometown to help my dad with whatever he has going on, I just feel better about filling it up knowing I'm getting way better fuel mileage than 12 mpg. It's just a personal thing, nothing against carbs.