Fuel Flow all over the place

[azjoe67]

I'll have to break out my scope, see if it shows anything.

In the mean time I moved the FT-60 to FF2 and it's not fixed, but better. On FF1 I would see 3-6GPH fluctuations, on FF2 it's down to 1-2.5.

[Markdun]

I scoped my erratic FF measurements (Red Cube, Rdac XF, Jabiru 2200, Xtreme EFIS) and we found a 60v negative spike on the ground. Fix was installing a different voltage regulator.

[rainier]

Yeah, those regulators have been trouble for a long time. Usually radio noise. First time I read that it affects a fuel flow sender.

[azjoe67]

Interesting. I haven't checked my alternator / regulator. It's worth a look.

[azjoe67]

I'm stumped. I've tried everything y'all have recommended, no joy.

I get the same bouncy reading with two different FT-60. I've tried known clean, measured clean, isolated power, no joy. (My ship's power didn't give me anything unusual on the scope). I've tried both FF1 and FF2, same readings. I've moved the FT-60 all over the place to see if placement makes a difference. Nope. I've tried both 5V and 12V on the pullup resistor. I'm on the clean 12V right now. No change. About the only thing I haven't tried is to use the clean power on both the FT-60 and the RDAC.

Any more thoughts?

Thanks.