I have a 1987 ford F150 4x4, 4.9 6 cylinder engine with 185000 miles, 4 speed Transmission( Granny low). It is kinda low geared and Im not sure what the rear ratio is. Has new plugs and wires. I took a trip down interstate yesterday to check my mileage and I was only getting 12.66 running about 70 MPH. So I refilled and tested again and drove 65 with cruise controll on and only got 12.50 MPG.
Does this sound about right for a 6 cylinder engine.
Any input as to what I might do to up the fuel mileage?

 

Well, without overdrive, that's not too far off. Actually, being a 4x4, you probably have 3.55 gears, and I wouldn't even cruise at 70 mph, personally. With 3.08's or if you had overdrive, that would be cool, but you're spinning the engine pretty fast with that setup. I would imagine you would get at least a whole mpg better by cruising 10 mph slower.

I get 13.5 city/15 hwy in a 1992 F150 X-cab longbed with a 351W and E4OD automatic overdrive tranny, by the way. Curb weight - 5300 lbs.

 

That's about what I get with overdrive in my '89 4x4. I think I'm going to need a rebuild here soon on the engine, but probably the transmission and clutch first though. I hope that will help. I think I have the 3.55 gears too. I love 'em for running around in the woods.

 

SS - what engine do you have? V8? That would be about average for a V8 4x4 w/ OD.

 

My truck (see sig.) I get 13-14 mpg highway driving pretty hard.

 

Wow I was hoping for about 15 to 18 MPG But maybe that is a far streatch.
I was thinking of putting a 4 speed with over drive in it to see if that might help.
Ohh I think I read somewhere too if you changer rear ratio you have to front ratio too? Is this right?
And Thanks for the replys
ZZ

 

I have the exact same truck, but it's an 89. I get about 14 or 15 with it. Are you running the stock tire size? With a bigger tire, your odometer and your mileage calculations will be off accordingly.

Have you pulled the codes? Sometimes an O2 sensor can cause poor mileage. Also a clogged exhaust will do it.

And yes, for a 4x4, if you change the gears you have to do both front & back. If you swap an O/D tranny in there, you might squeeze another 2 mpg out of it. Mileage is impacted more by how you drive it than anything else.

 

No I have the same 4.9 inline six. It's just an old tired farm truck. Well it used to be then it sat for a few years until the owner's daughter drove it for a while. Then I picked it up for $1300 and now it's my daily driver. I'm hoping to find a job (I'm 17) and build up the engine a little bit and some other stuff. And for some stupid reason, I get better milage in 4th than in OD.

 

i have a f-250 with a 351W and i only get 8.6mpg.........does that sound right to yall?

 

Yes if it's a 3speed and you like to drive at 75mph!!

 

My 91 nite with 302 and mazda5od got 18-20. my 95 4wd with 203 and mazda 5 speed gets about 12-14 right now.
Havn't checked with the new bearings yet. and still need to do a TPS.
And getting new clutch soon. Clutch isn't working properly. prolly a little slip on there every now and again.
I think i can squeeze about 16 outa my 4wd, but more would be silly to think of getting more then that.

 

Hmmm? My bone stock 87 F-150 Lariat 4x4 5.0L Auto (94K original miles) gets 18 Hwy and 16 round town. Of course I drive at or below the speed limit on the highway.

 

I have a 1994 Ford F-150 4x4 with the 5.0 and automatic overdrive. The truck has a 3:55 rear and Im running 31 in. tires. The best I can get out of it is 12.7 MPG driving it like a lil' ole lady. The truck has a K&N air filter and true dual exhaust with flowmasters. Runs great and has plenty of power..just crappy gas mileage..Any ideas to better this mileage would greatly be appreciated.
Thanks

 

My 94 351w auto with 3.55 gears jumps all over the place. It gets about 11-12 city and I have clocked 15.2 on highway but not consistant, I think it has something to do with planitary alignment in the solar system. My last truck 94 300i6 auto got almost 20, but it had 3.08 highway gears and couldn't pull s%$@. I would think that 12 with your gears and trans probably isn't too far off.

 

Depends on the land scape . If its flat you get better. Need to say where at. Had 88 F150 4x4 rag cab long 4.9 4 speed 3.55 rears got 14 mpg at 55 mph .Of course that was in 1988-89. My new truck 94 F150 Xlt Maf 302 E40d 4x4 sc lb 265 75 165 tire. Yesterday on 261 mile round trip interstate driving at 75 mph + on I80 in eastern PA with 3/4's of trip being is mostly flat I got 17.4 miles per gallon (87 octain) . I was shocked I have been getting 15+ mpg while country driving but never thought it would be that good.