Hi, I started a thread earlier about how I only get 10 mpg w/ my f-250 that has a brand new 302 in it. i was getting helpful comments, but unfortunately some smart remarks were posted by a certain individual who thought that I was complaining too much.

This individual seemed to think, that because I have a truck, I should not complain about gas mileage. This is true, but even so 10 mpg w/ a brand new engine is really bad, even for a truck. Most of you get 13-14 mpg, even up to 16.

My gas mileage may be caused by the fact that a 302 is just too small of an engine for an f-250 that weighs 6800 lbs. I hope that is not the case, because then there is nothing I can do about it.

My check engine light will come on, then turn off again. However, I checked the codes about a week ago, and got an 11, but since I have never checked codes before, I didn't know about the constant memory codes. So I thought that I was in the clear because 11 means system pass.

Now I know otherwise, but unfortunately, I think that my negative battery cable is still factory original, and it is not getting a very good connection, so about once every month or so, I will try to start my truck, and It will only click once, then everything will turn off, so I have to disconnect the negative cable, and clean the wires attatching to the terminal, which resets my codes, so now I can't tell what codes it was putting out before for the constant memory.

Sorry for the long post, but I have alot of problems that may affect my gas mileage, and I need help pinpointing the one that is causing it.

Thanks

 

Ok, I also kept up with the other post so I kinda know whats going on. Now that I hear about the battery cable, I'd say get that taken care of ASAP. Pulling the codes is the best source of direct info for your truck. I guarantee you'll never figure out your gas mileage problem without reading the codes. If they're being reset constantly, your never gonna figure this out.

Also, for those who are not familiar with the previous thread..please repost the axle code, trans type, 4x2 or 4x4 etc.

 

More information on my truck, it is a 1991 4x4 f250 w/ a brand new 302 and a 5-speed manual. it has 3.55 gears, and is a single cab long bed. The only upgrades I have done is a 3" flowmaster cat-back exhaust. And a k&n air filter

Yes I need to get that cable fixed. But I haven't gotten around to it yet because I have no time. And it seems like a time consuming job, because I don't know where the ground points are, or how to get to them. Another problem is money. I know that a ground cable won't cost much, but I am on very limited funds provided by my job at a burger joint, and can't spare very much. Most of it goes to gas.

I probably won't be able to do it until at least the 1rst of febuary, because that is when I get payed. seeing as how I blew all of my last paycheck fixing an off-road related screw up of mine.(broke the seal on the powersteering gearbox, shorted out my alternator, and got water under my distributer cap.)

Nate

 

Could a bad fuel filter cause bad gas mileage. It seems like it would give me better gas mileage, but less power because it slows the amount of fuel flowing. But less power would mean the engine has to work harder. Or maybe I just don't know what i'm talking about.

And w/ a truck that has dual tanks, is there one or two fuel filters?

Thanks,
Nate

 

clogged/bad fuel filter wont hurt your MGP.

Your truck is a 91 f250 4x4. 3/4 ton trucks are heavy alone, 4x4 makes the truck even heavier...

add that and the fact that you are running an older rebuilt ~91 302. the motor may be rebuilt but its not a newer updated 302 like a 96 would have. That motor might just be too small for that heavy rigg. I could see ~12mpg.

I might be picking up a 94 f150 2wd with a 302. the best I could hope for is 16mpg.. and this truck will be FAR lighter and less of a load on the motor.

 

Are your tires still stock height? If they are taller they screw up your speedometer and odometer readings. If so your mpg might be better than you think.

 

Nate

There is one fuel filter and if I were you, I'd change it. I don't really think its worth our time to argue over whether or not the fuel filter effects gas mileage. In my opinion, it does hurt your mileage and that's as far as I'm taking that. Its a cheap part and the " it can't hurt" theory applies here.

Battery cable...dude, go to the junkyard and find a nice one. While you're replacing it on yours, be sure to clean up all the grounds and any contacts it makes with a little steel wool or scotch brite.

Any 302 would probably perform about the same in this truck. Its probably not the best engine choice for it, but you can get passed that. A 351 would proably suite your needs a little better, but you've got a brand new 302 there so we won't even discuss that as an option right now.

Hmmm... trying to move a heavy truck, 302 aint cuttin' it...have you considered changing out your camshaft for a towing or off roading cam? Hopefully someone will read this that has done this and can chime in with some info on the results.

 

You are doing more than clearing codes when you pull the cable, it forces the EEC back to the initial default operating mode, which means it is not going to get the best mileage for a while (~200 miles), it has to get enough data to determine the best efficiency, every time you pull the cable you are forcing the EEC to re-learn what is best,

Fix the cable, about $2 for a new terminal, cut the old one off and install a clamp type.

If the gas is killing you, get a beater 4 banger, look around you can pick something up for 300-400 all day long. Might even be able to do some kind of a trade with someone, I only use my truck when I'm hauling or know I can waste the gas, I'm in the Talon the rest of the time @ 32Mpg

 

your talon gets 32mpg, thats crazy, it must not be AWD, or turbo, cause most of them only get like 20

 

i would buy an old beater 4-banger, but my dad won't let me drive anything but my truck till i'm out high school cause "i'm safer in a truck"

 

Smart Dad

 

Nate, we have an E150 Club wagon with the 302 in it. THe thing is a pig but we still get 16 empty and ~12 pulling a trailer. I think you have a bad sensor or two. Do you have cats on the trucks?

 

I replace motors all day long, Just because it is a new motor dosen't mean the supporting componets are. Injectors, have you had them clean professonially recently. Did anyone clean the intake manifold and ERG passages. Imagine the back of the throttle body being dirty so you have to open the throttle farther to let the same amount of air thru thus the computor reads a higher TPS signal. Do you replace the O2 Sensor every 60K? Your truck is a speed density system so it relies on the O2 sensor for feed back while in closed mode. Fords have the worst ignition system out there. Buy some MSD, or Taylor spark plug wires and a MSD or Crane coil. Run Copper or Iridum plugs not platinum. K&N or ACCEL Drop in air filter. 7.5 liter air box snorkle. Exhaust, these trucks cats are the most restrictive ones I have ever seen, Replace them with a cheap Dynomax cat if you don't have resrictive smog law like in CA. If you do smog it replace them with an expensive cat that is less restrictive.

Just a few places, start looking

Jason

 

I just ran my first tank of gas through my new (to me) 90 f250. I figured it out to be about 15mpg. thats with a 5.0 HO, 355 gears (I think), manual tranny, and 4WD. I was actually pretty happy with that.



It's about 25 miles roundtrip to work, with about 20 of those being highway.

 

HooRahh, NOt bad at all!!!!