Under reading fuel guages

[silent flyer]

I have recentlyacquired a used RV6.
The fuel guages under read dramatically. Aparently they were accurate but more recently have began to underead.

When the master is off, the needles ( both tanks) assume an electrical zero position way left of the empty position.

Has anyone had similar xperience with this?

Regards

Tony

[rv8ch]

Are they float type senders or capacitance?

[silent flyer]

Hi Mickey , I have only had the aircraft fo a week, and to be quite frank I do not know will have to find out from the builder when I get back home.

I have tried to upload a foto but I get an error message. Notsure what I'm doing wrong

Regrds

Tony

[rv8ch]

I know that capacitance senders can give different results depending on the type of fuel in the tanks (avgas, mogas, mogas with alcohol) but I don't know how that difference will manifest itself on the low end of the gauges.

The type of gauges might be included with the documentation you received with the aircraft, or perhaps you can contact the builder.

About uploading photos - Doug has a page that describes the process here: http://www.vansairforce.net/articles...ums/images.htm

[silent flyer]

Hi Mickey thanx for the info... Bye the way are you based in Switzerland.

Thats where I am at the moment. I leave Zurich tommorow evening...Back to South Africa.

I will get the info from the builder when I get back

[svanarts]

I have standard Van's fuel gauges and foat type senders. The fuel inidicators always show me as having less fuel than I really do. I go by time and fuel flow. I look at it as a safety feature.

[silent flyer]

Yeah I agree that an underread is a good thing but my guages have a gross underead..... They indicate less than half whenthe tanks are full.
Useless as an ashtray on a Harley Davidson

[rv8ch]

Originally Posted by silent flyer

Hi Mickey thanx for the info... Bye the way are you based in Switzerland.

Thats where I am at the moment. I leave Zurich tommorow evening...Back to South Africa.

Yes, I'm about 2 hours by train from Zurich. Feel free to visit any time - I'll be happy to send you directions. There are also RV7 builders very near the airport - Bernie and Alex. Perhaps you can hook up for a visit.

[silent flyer]

Hi Mickey,
back in SA now and have spoken with Trevor, who built the RV6.

He says that they are float type senders. The strange thing is that they are both under reading

Regards

Tony

[Jamie]

Hi Tony:

The value being read accurately depends upon a couple of things. First, there is a bend the builder must make in the arm of the float sender. I would surmise that bending this arm a little off would change the readings on the guages.

You could easily start the test by taking a multimeter and checking the ohm reading on the sender. If the tank is full, you should be seeing about 33 ohms if I remember correctly (this is in the assembly manual if he gave it to you). The low end is around 2 or 3 hundred ohms. If at full you're reading many more than 33 ohms, you know that there's a good chance the bend in the float arm is a little off.

You can do the same at the low end (i.e. by draining the tank). Again, check the manual for the correct ohms you should be showing. Someone that reads this can probably post the exact values (I'm at the office and don't have it available right now).

Your fuel gauges are basically a couple of ohmmeters marked in gallons instead of ohms.

If you're bothered enough by this (I know I would be) you could purchase a fuel gauge that can be calibrated, such as the Electronics International unit ($$$, but very good and a great company) or similar. Since they can be calibrated, it doesn't really matter if the arm swings through the full range, as long as the resistance changes throughout the range of travel of the arm.

Hope that helps,