I have an 84 F150 auto 300 six. Tough truck, still going.Tuned and all systems working. Please tell us how to get fuel milage out of these motors. 14 mpg is not acceptable. Ihave read many posts here, and most are geting an averge top milage of 15 to 16 mpg. This motor should be capable of 18 to 20 mpg. So please FoMoCo, help us out before we have to buy Chevys when the price gets to 2.00 a gallon.

 

There's so many things to do to get better mileage, but your stuck, a 16 year old vehicle of any kind won't get incredible mileage.

I would start with the basics, make sure your truck is running correctly first. 14mpg makes me think that it is, then go with a better exhuast, filter setup, and get somekind of anti-winddrag, like a tonneau cover or a campershell, or at least leave your tailgate down when you go above 50mph. Avoid stop/go driving, ease your driving. These all will help!

 

[font size="1" color="#FF0000"]LAST EDITED ON 28-May-01 AT 08:26 PM (EST)[/font][p]Here is my take on the situation....

Considering the weight of the truck and what-not... 14MPG is GREAT for a 17 year old truck.... Remember... you are not paying nasty expensive insurance like the NEW Trucks.. even if it is a cheby...

And your don't have the payments of a new truck..
And the NEW trucks really aren't getting much better mileage.. maybe 20mpg for a Fullsize truck at best...

Also... a 1984 Chevy with a 305/350 that is in working order probably gets the same mileage...

I drive a 1970 Ford F-100 w/360 it has 283,000 miles.. its a junkyard engine that has been in there for 40,000 miles. The orginal went @ 243,000(and it went because prior owner hadn't taken care of the engine...) I get 12 mpg , 10mpg if I have a load...

So not to sound harsh.. but DEAL with it....

Uzi... Yamaha Sleds, Honda Bikes, and Ford Trucks...

 

i wish i could get 14mpg out of my truck.











87 f-250
" if you are going to have a bear, it might as well be a grizzly"
4.9 granny tranny 4.11 gears

 

you have to look at everything that contributes to mileage.
for example, 4.11 gears with a granny tranny won't give you great mileage if the granny tranny has no overdrive, and even then, with the 4.11 you won't get real good mileage.
but, if you get an overdrive transmission, coupled with 3.08 or similar gearing, you can get better mileage. you have tradeoffs on pulling power, but it is cheaper at the pumps.
i have an 88 with overdrive and 3.08 swapped in from an 85 and get 17+ regularly.i use it on highway and incity and jobsite driving mostly. the occasional offroad for recreation requires dipping into low range more often, but i usually do well, with minimal problems.
i also find i break fewer parts with this setup than i used to. this could be due to wisdom and experience gained over the years, or shear luck, but it is a lot less costly no matter what.

 

i was just stating that 14 mpg isn't all that bad, my truck is not a dialy driver, it is used to pull and haul, it suits me fine, but i do wish i could get a little more mpg out of it. do they make a higher gear for the full floater rear? if i change to a weaker trans and high gear,wouldn't i have a f-150 with heavy springs? i think there is something i could do ( ignition exhaust etc. ) to boost mpg a little what do you guys think? i had thought about changing to a 5 spd but every one says the mazda tranny is a p.o.s. so i guess "you might as well have a grizzly" thanks, chad



87 f-250
" if you are going to have a bear, it might as well be a grizzly"
4.9 granny tranny 4.11 gears

 

To improve the mileage on an already tuned V-8 vehicle in my experience:

1. Improve the pumping efficiency of the engine. That means open up the exhaust and the intake to allow air to flow easier.

2. Improve the burning efficiency of the mixture. That means upgrade the ignition system, remove the EGR system (it robs fuel economy) and the replace the PCV system with a catch can system to reduce misses. Suggestions here are side-gapped plugs, MSD boxes, aftermarket dists, 9MM wires, etc. Don't ask me to explain the removal of pollution controls, I won't do it.

3. Improve engine sensor reponse. That means verify that all engine sensors ate operating properly. Thermostadt, O2, MAP or MAF, Abs. Pressure, etc. The better the ECU sees the engine, the more likely it will give the correct mixture.

4. Improve fuel delivery. That means blueprint and balance all injectors or rebuild and balance the carb. If its EFI, then get an adjustable fuel pressure regulator and gauge and set it to the lower end of the acceptable range. You will run leaner, so I would highly recommend and A/F meter at this point.

5. Remove unneeded loads on the engine. This means possible losses due to crank loads. Maybe a set of underdrive pulleys, removal of the air pump system (Don't ask), engine fan with an electric, etc.

6. Reduce moving loads. Thinner, lighter, low-rolling resistance tires, undercladding or ground effects to reduce the CF of the vehicle, tonneau cover can help, but the underbody really catches the wind.

If you can do all that, then you will have the highest gas-mileage I6 in the world.

Randy

 

14mpg? What's wrong with that? My 82 F-150 XLT Lariat Supercab LWB with a 302, Motorcraft 2bbl and AOD gets 7-10mpg, usually around 8.

 

I have a 1984 F-150 300 six with a np435 4 speed 308 rear 145000 miles on it. It will get 18 highway 14 city. This particular setup does real well on the highway but doesn't do well in stop and go driving. The issue as I have seen it is the Carter YF carb doesn't do well in idle situations (to rich)the combination power valve accelerator pump has a tendency to leak fuel into the intake ,either the diaphram leaks or the housing doesn't seat right and there is a vacume port in the bottom of the power valve well.

 

how about a thermostat change, what temp should i run?



87 f-250
" if you are going to have a bear, it might as well be a grizzly"
4.9 granny tranny 4.11 gears

 

Thermostadt: 192-194 deg F for maximum fuel economy.

That is your best option.

Randy

 

[font size="1" color="#FF0000"]LAST EDITED ON 30-May-01 AT 08:47 PM (EST)[/font][p]Poor fuel mileage is just something you have to deal with, there are maybe things that you can do to increase it but I wouldn't expect to see gains of more than 2-3 mpg in most cases. My mileage is not what I would call great, in the neighborhood of 13 mpg on the freeway.

specs:
-89 F250 at 61000 miles
-460 EFI
-5 spd w/ OD and Granny (love watching my wife lurch it when she starts in first)
-4WD
-4.10 gears in a full floater rear w/ limited slip
-Flowmaster and 3" exhaust from headers to the back
-K&N Air Filter
-305/70R's which probably lowers (numerically) the final drive ratio a bit since the stock tires were 235/85's.

-=Bigmike, or as my wife calls me: the one who will be riding the motorcycle to work if gas prices hit $3/gallon this Summer as expected

 

I wish I was getting 14mpg,only averaging about 10mpg,you'll get used to it...Dave1996 F150 5.0 5SP 2WD K+N Kit,Gibson swept side dual exhaust,JET module,Powertrax Locker,Shorty Headers ported to the heads,Billit short throw shifter,Sportech 1" rear sway bar w/poly bushings,more to come,too much to list

 

I'll tell ya what's even worse. Getting this kind of mileage and having a SINGLE 15 GALLON TANK!
I feel like all I do is look for gas stations.

 

Have three such trucks - 84, 85, and 86. All F150s with same 300ci engine. 84 is 4spd and gets mid teens in mileage. Other two are automatics (86 is 4WD), and mileage is usually single digits. Have been told that mileage problem is due to automatic trans, and its not going to get much better. Anybody verify?