Fuel Flow Guage Indication at Rest

[Cliff Biggs]

Still can't believe how well this Twinkie does (67 NA), but I have a question. Starting to tweek little items and I see my FF guage, when nothing is running and no electric power on, both needles sit some where above 2 to maybe 3.5 GPH indication. I would think that they should both be indicating nearer zero and that this may be contributing to my higher FF indication that I see when compared to the actual fuel burn from the tanks vs time of flight. I lean to peak and I'm usually above 10,000 feet in cruise. Yes I've thought of clogged injectors but haven't had time to pull and clean them. I do have an industrial ultrasonic machine (I used to sell them) at my disposal to clean them with.

[skipsouthernsky]

Dear Cliff,

My take is there are two options that you have.

One......remove the guage and have it overhauled.

Two.....put in an engine analyzer with fuel flow and have much more accurate information. Then just leave the required old guage in the panel and laugh at it and whatever slightly erroneous information it is telling you. If you are really lucky, (probably not) you can legally remove the old inaccurate fuel flow. Don't worry, I do the same with VOR's these days. When established on a Victor airway, I use GPS for primary (much more accurate) and sometimes turn on a VOR (much less accurate) and laugh at the scalloping and weakness and all. New technology sure puts the old stuff to shame.

I wouldn't waste my time running after clogged fuel nozzles and such. Low probability of being your true problem. Might cause higer indication when the engine is running, I just don't think that would cause 3 gal/hour when the engine is off.

Sincerely,
Skip Dykema

[skipsouthernsky]

Cliff,

One other test you can try.......Try cracking the B-nut at the flow divider where the line comes off and goes to the fuel flow guage. See if that reduces the indication to zero. That should tell you if the problem is in the guage or the system. Or better yet, crack the B-not or whatever attachment there is at the back of the guage behind the panel. See if the guage goes to zero or not. My recollection is that there is a restictor in the line where it comes off the flow divider, maybe that opening is gunked up.

Sincerely,
Skip Dykema

[Cliff Biggs]

Interesting thought about the guage line I'll give it a try but both would have to be clogged as both indicate high when the engine is shut off. I have an Ei FF system in my Mooney and like its accuracy. Down to .2 gallon on 50 gallons used. still have to go back to what dd we do 40 years ago before all the electronics. My twinkie burns 20 the first hour and 15.5 from then on most of the time.