Floscans installed, not really working though.

Got everything hooked up, gauges go through the self test and respond to both engines running. The needle shake appears to be almost nothing which is great, but wait there's more!

I'm getting a wide fluctuation/swing on both engines. At idle, they will be around 1 GPH for a few seconds and then might swing as high as 16GPH and then come back down somewhere else. This is a Twinscan unit, GPH only.

The first thing I thought of was the 1-2" rise out of the sende units. So, I unbolted one Racor, tipped it back and zipped tied it in that position as a test on the port engine but it did the same thing.

When they settle down, the lower range seems to be about right but obviously something is way off. Jeff, I read your posts about small air leaks. Did your gauges do the same thing? No fuel leaks, everything looks good. I wound up making new fuel lines with brass aeroquip connectors.

The other thing I noticed is that they gauges don't respond when you rev up the RPM's. I was sort of expecting them to move like tachs but maybe there's a delay in processing before the needles go into motion. Revving up and down in the slip doesn't do much. The total gallons used is ticking up so it's measuring something.

Bob

I would tend to run the engines at a cruise power for a bit. The system needs to purge all the air out. Even at high rpms, in neutral, there is not enough fuel flow to purge the filters, new hose, sensors, etc. If, on the other hand, the engines have burned 2 or 3 gallons and it is still gauging wildly, I'd put in a clear inspection hose at the fuel pump inlet.

One problem that sometimes crops up is air leaking. You may have your fuel system tight enough not to leak fuel out but such that you are sucking in some air somewhere. This can confuse your flowscan response.

Also, if you've not already done so, check the wiring including the grounds.

I know that mine has some damping so that response is not instantaneous. At the dock, the response is fairly small since no load results in little fuel consumption. These are not tachs but on my installation, you see the expectable changes, damped and slightly after you might expect.

Good luck and, of course, your milage may vary.
Bruce Clarkson

You have an air leak before the flow meter(s). I had to relocate mine to BEFORE the shut off valve, since it was allowing air to be sucked in by the fuel pump--amazing but true. Readings smoothed right out after that.

Jeff

great, looks like I'll have to re-work my plumbing. Right now it's copper line from the tank ---->shutoff valves---->flex line---->Racor--->sensor---->fuel pump, etc.

I used pipe dope on all the new connections/fittings so those should be good. I didn't touch the hard line from the tank or original shutoff valves.

Jeff, is it even worth trying to use new pipe dope and re-tighten the shutoff valve connections or should I just move the sensor?

Bob, I would try to confirm if your getting air in the line, like Dave said.. I might start with a piece of clear test tubing or a clear inline fuel filter on the outlet of your shutoff valves to rule out the hard line connections first or if it is easier check the fuel path just prior to the fuel pump to confirm the down stream side of the pump.

mike

thanks Mike, I'm going to change the setup a little. I just ordered 238 micron in line filters which have been recommended. I'll put that before the sensor as my pre-filter and then go into the Racor. That will eliminate the shut off valves as a potential problem source as well as the 10 micron Racors before the sensor.

There's a note in the floscan directions that says " a dirty fuel filter or one that's too fine (1-25 micron) will draw vapor bubbles out of the fuel causing fluctuations and high readings".

That's exactly what's happening now.

In following this thread because I plan on adding Flo Scans. However, my memory is not what it used to be, I read the install directions a few months ago and seem to remember the directions stating the Flo Scan valve should be in a vertical position. I remember this because it determined where I would plan on placing these valves.

I may be wrong, not sure and have not gone back to re-read the install directions. Thought it would be good to offer this as a possible solution. It seems to me that if air was entering the system, you would have noticed a performance issue.