johnr9q

I recently purchased a module and am considering an overdrive unit to improve my fuel economy. I ran the module thru various trials to determine if it improved my fuel economy. Each trial was approximately 100 mileswhich eats up a lot of time and money. I have explored a mpg gauge (the one on the overhead isn't accurate enough) and can't find any. My next thot was to get a 3 gallon glass jar and put accurate graduations on it and mount it in the cab with me. I would fill the tank and then run a line from the small hose at the diesel fill location (I think the small hose is a vent hose for the tank) (I am referring to the fill location where you stick the nozzel to fill the truck - there is a large hose that goes directly to the tank and a smaller hose off to the side) I would disconnect the small hose and add a hose to the end of it and run it into my cab where I would have the 3 gallon glass jar. Gravity would keep the tank full as I drove down the road and the 3 gallon jar would empty. I could go at a constant speed and observe the fuel used with the graduations on the jar. This way I would get an accurate MPG reading without going many miles. Does anyone have an opinion as to if this idea would work or not? I wonder if the fuel cap seals adequately so fuel wouldn't escape? When the truck tank draws down where is air allowed into the tank to keep the tank pressure balanced and would this cause a problem with my idea?

big jimmy

A glass jar is asking for serious trouble.

Anything carrying fuel in the cab is asking for trouble.

The tanks in or on our trucks are designed not to spill fuel in an accident.

Anyway, I know some will say this is being too careful. But if you have seen a burn victim from ignited fuel, you won't think the risk, however remote, is worth it. There are better ways to figure fuel consumption.

Big Jimmy

infidel

There is a very accurate fuel usage meter available but it will cost you>
http://www.floscan.com/html/blue/index.php

Rob Mitch

I believe you will have a change in fuel volume as the fuel in the tank warms up due to the fuel return from the injector pump.

dhvaughan

don't do it. fuel in cab is bad. fuel in glass is bad.
patience grasshopper...why waste fuel - just wait until you actually going somewhere and hand calc.

johnr9q

I should have said a clear bottle and I am only going to do it for short driving sequences where I am actually testing something. I will look into the floscan fuel flow meter that Infidel suggested, at West Marine on Monday. I have checked them before and pretty costly. Rob Mitch said: "I believe you will have a change in fuel volume as the fuel in the tank warms up due to the fuel return from the injector pump" With a full fuel tank I wonder how much this will effect the observations?

jrs_dodge_diesel

We use these on some of our Coast Guard Small boats. They work quite well and also keep track of total fuel burned that can be reset similar to the trip odometer reset.

Tree DR

Try this www.scangauge.com I've been useing one for several different vehicles now. It may not be dead on its calculations to start with. Yes you can ajust it to match hand calculations. Once I had it corrected it was within .2 consistantly. Yes it shows instant MPG as well as Tank, Current trip, Today, Yesterday MPG. It also shows you MAP and Load, among other things.

johnr9q

Tree DR: My Truck has an overhead miles per gallon gauge which isn't extremely accurate (within 15%). I talked to a fellow from scan gauge recently and he said if my overhead monitor wasn't accurate then I shouldn't expect the Scan Gauge to be any more accurate. He said their experience shows the Scan Gauge to be within 5% accuracy. Sounds like you are getting very accurate results from your scan gauge, is your overhead MPG gauge equally accurate?