Do bad pumps mess up your Scangauge readings?
 

Three times now, I've filled up and found I needed to add 30% more or less fuel than expected. This drastically messes up the MPG readings. I wish my Honda got 80mpg as it's now reading, but it's not really happening.

I've been resetting the ScanGauge II to defaults at the next fillup and starting over. I get fuel at several gas stations, so it's hard to pick one as being the problem.

Ideas?

There are several options here.

- Fill up to the rim of the filler tube. That way you know it's full.

- Adjust the Scangauge to the average fillup. If it says 10 gallons and you put in 11, adjust it to 10.5. After a couple tanks, it'll average out pretty well.

- Keep a log with the SG readings and pump gallons. Calculate a running average offset and use that. I use this method, with a 12% offset (more gallons, less mpg compared to the SG default).

You aren't supposed to reset every time you fill up. That defeats the purpose. You select the fillup option, then adjust it until it matches how much gas you put in. That applies a correction factor

I think the problem was going to several fuel station that filled the tank to different levels before auto-shutoff. I stopped going to two of them that gave the most drastic fill amounts and the numbers are working out better now.