hey everyone im new to this site but i have been reading for a couple weeks. i just bought a 96 f150 2 wheel drive supercab 5 speed 5.0 200,000 miles. looks like whoever had before the guy i bought it from took real good care of it, but the last owner let it go down hill a little bit. when i bought it it was missin real bad and had a horrible vibration going down the highway. the miss was a plug wire off and the vibration was a u joint. the check engine light was still on and still had a slight miss. i went to autozone and had them scan it, the codes are 1351 and 0420.
i bought an icm and of course it was gray. didnt change anything, went to the junk yard got a black motorcraft and the truck runs way better. that also took care of the check engine light for a day or so.
i put $20 in gas and went to town, 70 miles later im on E. i figured the mileage (i know this isnt an accurate way) but it came up to less than 10 mpg.
so my question is, could that 0420 code be the problem? could the o2 sensors be giving me horrible gas mileage? any other ideas? thanks guys love the site!

 

Yes, the O2 sensors could be the cause. It might also need a tune up.

Chris

 

Less than 10 mpg sounds bad even for the F150 . It probably could use a good tune up. OTOH, I have a pristine '94 F150 XLT with 76K miles on the clock. Runs beautifully, no codes, no symptoms of problems, all new wires, plugs, dist cap, rotor, high voltage coil, advanced timing, all synth fluids, Seafoamed, etc. etc. And i just checked my mileage yesterday and got just a shade over 12 mpg
Some folks claim to get over 20 mpg from these trucks, but I really don't know the secret of how they do it.

 

You can't base milage on the fuel gauge.. period. Reset your trip meter when you fill up and drive it until it needs gas again, then mark down how far it went and how much fuel it takes to top up the tank(note you don't have to run it dry). If it really only goes 70mi on a tank you have a big problem, if it's a dual tank truck you have the fuel transfer problem and it's dumping half the fuel into the other tank and then onto the ground if it gets to be completely full.

 

I put the operative word in bold in the quote above. Anybody can claim 20MPG but I would have to see it with my own eyes to believe it. My F150 has the 5.8 in it, is 4x4, had a tune up late last year, even changed the o2 sensor then. Its got 109K on the clock. I keep the tire pressure where it is supposed to be and drive it with some sense. I get 13-14 in town. If anybody with a similar truck to mine is getting 20 MPG, in town, with it they are either lying or suck at math.

Chris

 

I think it's only 6cyl owners that can hope for 20mpg

 

I think that 13 to 14 around town is pretty good for a truck like yours. If I really try for economy and avoid stop and go traffic, I can get around 14 mpg. There are a number of guys in the Ford F150 Forum who claim that 20 mpg is in the low range of what they get. They suggested a number of modifications which were all but guaranteed to produce that kind of mileage. I did them all but could not improve my mileage in any significant way. They say that there is probably something wrong with my truck. They might be right, but if there is something wrong with the truck, I have not found it yet even after checking for codes, carefully observing performance, checking for oil consumption, etc. I have not yet checked the compression or did a leak down test. It's just that my truck is in really nice condition inside and out and runs absolutely beautifully.... It's hard to believe that there is something wrong with the engine.

 

Some of the I6 guys can pull 18 to 20 miles to the gallon. I could run my truck 80 miles an hour or more and average just less than 17 mpg. That was with the 3.08 R&R. With the 4.11 I get 14 MPG, 16 at BEST.

 

All these guys have 5.0 V8s

 

I agree bladez, 14mpg is not bad for a V8 around town, even if the V8 is a 4.9L 302.

The main thing is keep the gear ratio high (but not too high).

 

thanks for the input guys. i know i didnt figure the mileage accuratly but the truck is just getting used to pick up material for work, so i havent filled it up yet. it is a dual tank truck, when i bought the guy was using the front tank, but it leaks so i started using the rear tank. i wonder if i am having a fuel transfer problem? the front tank doesnt seem to be leaking now that its not being used so probably not? i have done a tune up on it. i looked this up on this site and seen a few posts saying it may be the fuel regulator or a fuel pressure problem. i havent changed the fuel filter(s) yet but i would doubt that would make it use more fuel.
when i bought the stuff for the tune up i also bought 2 o2 sensors not realizing i had a 3rd one after the cat. what do you guys think about cutting the cat out and just welding a pipe in there? will the o2 sensor thats after the cat work correctly? thanks again!

 

well, ive done extensive note keeping with mine......302 v8 308 gears e4od and i am knocking down 16 in the city, sometimes a little less if i play around any.....

highway mileage is around 22-24 depending on terrain and how much a hurry im in

 

YES ITS A 4.9!!

Thanks for clearing that up dude. I'm always happy to know I have an engine bigger than a lot of today's f150 V8s, that has two fewer cylinders, rods, etc, to wear. And it's a ****ing beast on the low end, paradoxically making it one of the better heavy haulers and one of the best economy engines at the same time.

I can't lie, I don't keep mine in tip-top shape. All factory parts, assorted plug wires from old tractors, no EGR, and too many old sensors to count. I'm 20 and I drive fast enough to keep up with the Jersey drivers in black Hondas, and I get 15 MPG city/ 19 highway. Just sayin'.

 

im looking for a big six truck now....want to take the old girl off the road and start doing some serious sprucing up.....

 

So you drive it hard and race Hondas and still get 15/19 mpg? Congratulations on your gas mileage. But I think you guys with the high mpg's must have different trucks than I have.