Paul, here is a link to some information on integrating amplifiers.
You'll have to come up with component values, to see what works. they are
tricky circuits. I'm probably going to go another route, like maybe using
the DAQ system to totalize pulse on time and calculate fuel use.

http://www.electronics-tutorials.ws/opamp/opamp_6.html

There is another circuit, I remember seeing, still trying to find it in my books.
C. Smith

Thanks for the link Craig. Using the data acq works well but then you need a Net Book
in the cockpit at all times and somebody must write the software. If you do please share
it on here. It would be a good example and a start for other real time data displays.

An off the shelf digital voltmeter is all you need if people don't want
to have Net Book in the cockpit.

Paul Lamar