Brick-thanks. If the gauge think I'm in the Prizm or Prius,and it actually reads flow to a single injector and them multiplys by 4 instead of by 6, then it would say I'm using 2 gph instead of the 3 gph I'm actually using.The error could have been that large- roughly 30 mpg instead of actual 20 mpg.I only used it for an entire tank once ,and the reading was about 24mpg vs actual of about 15.5 mpg.
I will go play with it.
Thanks for the help.Charlie
PS I was a lot more puzzled about the error than the actual poor mpg(19.4).I had plenty of reasons to get poor mpg(dirty filter,wind,old plugs,didn't D/C CC on uphills like I usually do,less roadwork with 45 mpg speedlimits).