Leak checked RH fuel tank. I firsts hooked up a tube manometer with blue died water in it but the tank leaked rapidly when pumped up. Found that the fuel cap was leaking. Adjusted the fuel cap so the locking lever wouldn't turn and then backed off the adjustment just to the point where it would close. This slowed the leak rate but the water level in the manometer still dropped. Disconnected the manometer, removed the tank from the spar and put it in the cradle. I then put a balloon on the vent line and sealed it with duct tape. Next I pumped the tank up with the bicycle pump until the balloon inflated. I used soapy water to check all of the rivets and joints for leaks but found none. With renewed confidence that the tank didn’t leak I put it back on the spar and reinstalled the manometer tube to the vent tube. This time I tighted the hose clamps more and put duct tape on the end of the tube where the vent line exited. My thinking was that the earlier drop in the manometer was due to a leak in this area. I then pumped the tank up to the point where the level in the open end of the manometer tube was 27 inches higher that the other side (one psi). As of this writing (1/2 hour after pumping it up) the level is holding. The weather forecast calls for stable atmospheric pressure over night so if there are no leaks in the tank the level should remain the same overnight….we’ll see
Edit from 6:50 on 6/27 (the morning following setting up the manometer) - the water level dropped about 3/4 inch but the atmospheric pressure went up a little so a drop in the manometer water level would be expected. I created an excel spread sheet to record the water level delta from the original, and atmospheric pressure. The spreadsheet then calculates tank pressure drop based on the water level change compensated for changes in atmoshperic pressure. My initial reading shows a pressure drop of .052 PSI which is pretty good but when pumped up the tank last night I only made a rough measurement of the water column height with a tape m
