Hey guys I recently purchased a 1995 f150 short box with the 300 I6 paired with a 5 speed manual. One of the main reasons why I got the I6 is becuase everyone said it won't down the gas like a V8. Something like 15 mpg. Well from my driving so far I've noticed I've gotten more like 11 or 12, not what me or my wallet like. So is this to be expected? The engine only has 128,000 on it, runs great and doesn't burn any oil. I also just changed the oil and stuck in a new air filter last weekend.
If this is not normal, what do you guys think is wrong? Now that I think about it it could be my driving habits. I can't really help that though as I live in hilly Minnesota so I'll be cruising in the 5th gear overdrive at about 55 or 60 mph, then I'll get to a hill and I have to downshift to 4th and rev it up the hill at about 55 mph, then shift back into OD. That's probably not good for mpg but I really don't have a choice because if I stay in OD I drop down to about 50 or 45 mph depending on if there's a big head wind or not.

Thanks if you guys have any input on this.

Edit: I am a teenager so I guess I tend to drive like one, not crazy but not like an old man. And I will admit I'm not the best at driving a stick, I don't stall or buck it but I'm not the smoothest, could this be part of the problem?

 

Mines a 96 long bed I6 5 spd currently 203000 miles I have averaged 14-17 city and up to 19 mpg highway.
Your shifting for hilly terrain is normal driving and should have little effect. I think that younger drivers tend to keep there foot in it harder (put an egg under there) than old guys (me). When were the plugs last changed, old worn plugs won't burn gas off correctly contributing to poor mileage. As your overall experience driving improves your mileage may also. When money was tight I was putting 10-20 dollars in the tank it seemed like I was always putting gas in the darn thing as things got better I started filling the truck up just seemed I could go further. Back when I was a whipper snapper (16) my 77 F100 with I6 auto trans only got 6-8 mpg but I never took my foot out of it. I was always racing around setting the world on fire, so I thought. Enjoy your truck

 

My 94 f150 with 5.0 and e4od gets upwards of 18 on the highway with good fuel and no headwind. Been averaging about 15-16 this winter. My opinion is the 300 isn't a higher rpm engine. All its power is torque and already maxed out at highway speed. Each to their own I suppose. 302 has its drawbacks like anything.

 

Thanks, and about replacing the plugs, I have no idea when the plugs were last changed or if they have ever been changed. Maintenance didn't really seem to be on the previous owners priority list, as when asked he was not even sure when the last oil change was. With that being said I'll be heading down to the local parts store today to pick up new plugs, and possibly new wires too. If I do end up changing the wires, I know with some engines you have to keep certain wires separated to avoid misfires, do you happen to know if there are any that need to be separated on the I6? Thanks

 

check tire pressure.

jack up each tire and spin the wheel by hand to check for dragging brakes (this is also a good time to visually inspect your brakes and check for play in steering and wheel bearings).

if he cant remember the last time he changed the oil then chances are good that the dist.cap and rotor are due ...at least give them a visual inspection and check the timing .

 

Just picked up new plugs, wires, cap, and rotor earlier today. About what you said for brake rub and/or bad wheel bearings, if noticed when driving if I take my foot off the gas I slow down decently fast. I'll jack it up later and look at the wheels, it'll be easy to see if the brakes are rubbing but how can I tell if the bearings are worn? Thanks

 

Possibly worn O2 sensor, does it have a MAF sensor as well? Fuel/air ratio, lean or rich, is set according to basic information fed to computer. Garbage in = Garbage out.

Can still look at plugs like the old days. Mark each plug from each cylinder so you can see where it came from. Here's a good page on reading plugs. Post some pics of the plugs out of the engine when you get a chance.

The "Ground-Strap" = Heat Range
The "Plug's Base-Ring" = Jetting
The "Porcelain" = signs of preignition/detonation



http://members.uia.net/pkelley2/sparkplugreading.html

 

I had a 96 f 150, and mine was having issues with the plugged emissions system in it, i bought a set of high flow cats and took out the emissions system but if you don't want to spend 300-400 on high flows you can always go underneath with a drill and drive a hole into it and drain out the stock cats but it will sound like a 1982 straight piped grain truck

 

Many came with 300 gears in the diff...that could explain the reason for downshifting...3:50's were much better overall.....the 300's on flat ground will give better mpg but, in real word, the 3:55's provided much better results!

 

x2

If the timing is retarded, it will affect both power & economy significantly. Given the PO's response, it probably hasn't been checked for years.

 

Maybe, but the base ignition timing won't move on its own. Not enough to cut mileage by 2/3rds anyway. Agree it is worth checking though.

 

A line broke when I was removing the plugs today, it was green and connected to where the red circles are. I believe it is a fuel filter vacuum line but I'm not sure. Can someone verify this? It was extremely britle.

 

That's your EGR valve. You will have to replace that line to keep everything happy.

 

But if I need to drive somewhere I can just plug it off as a temporary fix right?

 

Plug the end down at the solenoid off.