I have refueled my truck 8 times now since I bought it. Until recently I was just envious of you guys that are getting 18 plus MPG. The best I could do was about 15.5 mpg. The last 3 fuelings have gone steadily downhill. I show 14.8 mpg then 11.5 and finally yesterday I show 12.3 mpg. I don't know for a fact that the odometer is right but the speedometer is pretty close. The truck is stock as far as I know. There is very little smoke except for the time I was under the hood working on something and I was gunning the engine. Next door neighbors wife was in her carport vacuuming her car. Need I say more, when I looked out from under the hood her house had disapeared in the cloud. There is no indication of low fuel pressure. Cold or hot it starts as soon as the starter bumps the engine. I am running a stock air cleaner but it is new. No fuel leaks evident. Rear tires are 33 12.50X16.5 at 75lbs pressure. Transmission doesn't appear to be slipping. I know there are things to do to improve mileage; timing, bhaf, and pods but why would the mileage drop like it did? If the injectors had gone that badly I would think that it would fog the road. I haven't been towing anything yet, and mostly city driving at 45 mph with some trips of 240 miles. My right foot does get a little heavy. I don't remember the exact ratio of the rearend but it is according to the tag a 3 something. Got to remember to write it down for my sig. Hope everyone had a great Easter.

 

I can tell you that when my fuel filter gets dirty my fuel milleage will drop off. Have you checked that lately.

 

It all really depends on how far you drive. I roughly drive a 1.5 to 2 miles to work a day. My truck never really warms up untill I pull into the driveway to work. Somedays when it's really cold I have to drive around some extra to get er warmed up. On average I get around 14 mpg Monday through Friday but when the weekend hits and I make a road trip it gets as high as 19 or 20.
Just my two cents. Jethrro

 

I guess I will change the filter. That is the only thing I haven't changed since I got the truck. The PO said it was just changed and I have only put about 2300 miles 0n the truck. BTW I didn't mention that the truck has 184k on it. Thanks for the response.

 

I don't beleave that you truck has the over drive? 727 (3sp tranny)

if it don't then that is were the milage comperison is coming from!

Mine is a 5sp stick and i get 15 in the winter and 17 in the summer unless i'm pulling my trailer and then it 14-15!(4.10 gears)

By the way mine had 215,000 and theres guys her on the form w/350,000+miles and still runing strong!

 

When was the last time your valves were adjusted? That may help a bit. And yes if you have an 89 you would have a plain ol 727 non overdrive tranny so that doesnt help you at all.

 

Your getting 15.5 mpg in town. Thats pretty GOOD. 12 mpg aint so hot. I would check your odometer. Get out on the interstate and run 100 miles using mile markers. If it indicates 94.5 miles its 5.5 % off.

I get between 12-15 mpg in town, I don't have an odometer so I don't know for sure. I know its way better than the PSD and I've checked it alot.

And one other thing if you drive in the city alot you build up alot a funk everywhere in the engine. You need to either load it with some weight, pull something heavy, or get out on the interstate and run it hard, get some decent heat in the engine find some long hills. These things weren't designed to be puttered around for months at a time. I have to do this because mine hardly ever sees the open road.

 

There's no doubt in my mind that your odometer (and speedometer) are off by more than 5% - maybe more than 10%, depending on what the loaded radius of your tires are (distance between the ground and center of your wheel/hub). The factory speed sensor was not calibrated for 33" tires, more like 31" or slightly smaller.

This error will not only impact mileage calculations, but change your shift points (they're based on speed - at least on my '93). I actually ended up buying a speed claibration unit from Superlift that allowed me to recalibrate my speedo.

That doesn't explain falling mileage, but it would result in overall erroneous lower numbers. Even a 5 mile speedometer check will give you an idea of how far you're off.

Here's the Superlift Truspeed: http://www.superlift.com/accessories/truspeed.asp

 

Mine sports the grampa look, stock steal wheels and tire w/ext. grampa camper shell