I've been thinking about what could possibly put me in the < 4mpg range, and the only think I could think of, with the truck running good, was a leak. Either a slow leak all the time, or the fuel bowls overflowing into the manifold and then the gas cooking off after I shut the motor down. (And I have smelled gas in the garage after driving it.)
So, today I made a run down to a truck stop that had a Cat certified scale, so I could weigh my truck. (It weighs 3400 pounds, btw.) I filled up at a station in Richardson before I left. Then I filled up at the same station when I got back. I drove normally, for me, reaching speeds of 72 once, running in fifth gear at 65 most of the time. (Over 70 gets a bit "hinky" - the truck shakes.)
My odometer readings were 543.2 and 555.1 respectively, and I bought 2.405 gallons of gas. However, I know darn well that that trip was more than 6 miles one way (the highway exit numbers tell me that!)
So, since I had both addresses, I checked mapquest. Total distance was 30.44 miles - 12.67mpg.
What I can't figure out is how the speedometer could be so accurate yet the odometer is clocking about 1/3rd the mileage. I'm going to have to check the manual, because I may have missed a setting somewhere. (It's electronic.)
Anyway, the mileage isn't great, but it's nowhere near what I thought it was.
I haven't had time to read all your posts, so I'll do that now and comment on anything I need to. Thanks for everyone's input.
