![]() |
I gather you are not the builder.
THIS IS A POTENTIALLY DANGEROUS SITUATION. RV's are not designed to use a "Both" position. If you draw one tank down while on both, the pump will suck air rather than pull gas from the other, full tank. (Unless the airplane has been modified to have a gravity fed sump tank below the valve, rather unusual). Are you sure "both" does not actually correspond to "right" (e.g. wrong faceplate lettering)? Check for blockage (mud dauber nest?) in the right vent line (just open the tank cap, and see if you hear bubbles when you blow in the vent). |
Quote:
|
As Bob already said, low wing airplanes do not typically have a both position on the fuel selector (there is a lot of info regarding why, in previous discussions that you can find with the search function).
If your RV-8 does have a both position (cant tell anything from the photo because it is so out of focus) you have a not per plans fuel system which could cause you trouble at some point in the future. |
Quote:
1. Firewall forward, remove a fuel supply line route it into a container. 2. Take a wooden dowel, stick the tanks, mark the level. Maintain log of levels 3. Turn on your pump, pump out some fuel into a dispenser with the valve in various positions. Make a determination on what the positions are ACTUALLY doing. Correct indicator as necessary. Get help from a qualified mechanic or RV builder for help. Both is bad. Thank goodness you have the option to deal with this on the ground. What you will probably find is that both is actually both. And you should not only not use it, but it should NOT be an option on the indicator. Also determining that both is both, can be tricky. What you might have to do is remove the wing root fairings, and remove the fuel supply line from the tank, and cap it. One at a time, to ensure you know what the valve is actually doing. |
Gauges
All of the above is good advice. However, in the original post you mentioned "the gauges". Did you confirm visually an uneven fuel flow by looking in the tanks? Gauges can lie.
|
Quote:
Thanks everyone for the advice. I have no intention of flying to figure this out...that's why I'm looking for diagnostic tests to perform. The vents are faired and screened so that's the first place to look. ![]() Thanks Kahuna - lots of good ideas there. |
I think you need to actually understand that BOTH is a bad idea with a low wing aircraft. If you have a BOTH position, don't use it. Feed from either LEFT, or RIGHT only.
|
Quote:
A Both position works on a high wing aircraft because gravity will cause the tank with fuel to feed even if the other tank is empty. Both positions are bad, bad news on low wing aircraft, unless there is a header tank that is fed by gravity from both wing tanks. |
Quote:
![]() |
| All times are GMT -6. The time now is 02:17 AM. |