I am having the same issue with my 90 trooper. I fill up and it will go about 200 miles to empty. Who knows the size tank for a 90 trooper?

Tank size does not matter.

How many gallons did you put in per those "about" 200 miles.

Next time take the exact number of miles driven since the prior fill up and divide it by the number of gallons it takes to fill the tank. Tank size, "about" miles and "about" gallons are not relevant. You need to know the actual miles and gallons to get a real MPG figure.

Michael

Yep, that's why they call it "miles per gallon"... <img src="/forums/images/graemlins/rolleyes.gif" alt="" />

what size tank is in a 90 trooper?

I believe that it is 21.9 gallons.

One thing nobody is talking about is the tire correction factor. You need to increase your miles shown on the odo to what you actually drove. This is because you are getting lied to by the odo seeing as it still thinks you have a stock tire size on.

Correct this and see if your milage numbers don't look somewhat better?

Joe

That is correct. <img src="/forums/images/graemlins/kewl.gif" alt="" />

Richard <img src="/forums/images/graemlins/patriot.gif" alt="" />

I should mention that my tires are 265s or 32". Not sure how to factor that in to the mileage calculations though...

This rig had a tune up not too long ago; the plug leads look almost new and it runs like a top (except for the petrol usage) and I changed all the filters/fluids.

I need to find a way to read the codes (without paying $85 at Canadian Tire). Maybe the next step is to clean/test the EGR or just go for a really long highway drive...like to LA.

BH

What size were the tires from the factory? I seem to recall 245 something, but can't recall the rest right now.

It's just simple math basically. For example, mine came stock with 235/75/15s. I now have 33s. That's roughly a 11% difference in height. So, my speedometer/odometer will be 11% off. And once I fill up, I take the mileage that's indicated on the odometer times it by 1.11 (adding the 11% to the miles already) and that gives me the actual miles. Then take the actual miles and divide them by the number of gallons used. That should give you the correct mpg. <img src="/forums/images/graemlins/kewl.gif" alt="" />

Richard <img src="/forums/images/graemlins/patriot.gif" alt="" />

Yeah what Richard said will work fine. You need to do this or you will get some bad numbers. You will be showing fewer miles than you are actually driving.

Joe

Well, since I'm running 265s, they're 8.2% larger than stock 245s. So even if I account for the larger tire size, that's still only about 10.5 mpg.

Distance: 177miles
Gallons: 18.2
Adjustment: 1.082
MPG: 10.52274725

Not too good even with the 'larger' tires...

BH