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QB tank vent leak

TomSpencer46

Active Member
Filled my QB tanks for the first time yesterday. The left vent line dripped a little fuel. Thought ok got in the line while filling. Next step test boost pump. It was slow to start but got a good flow from the firewall fitting. Reattached the hose to the engine pump. And tested again no flow at the throttle body. Thought maybe the engine pump diaphragm in the pump was stuck. With the mags off used the starter to turn engine over fuel pressure went to 18 PSI with the boost pump only the pressure is 1.6 psi. Need to call airflow performance on this.
Before leaving the hanger noticed the wet spot under the left tank vent was larger. Fuel was slowly dripping out checked the tank and there is over a inch of air under the vent line end next to the filler. My guess is the B nut on the inside is not tight or there is a crack in the flare. Removed the vent line from the lower fairing and reattached pointing up. Leak fixed but can not fly this way. Will call Van's on this one. Thinking of the fix could I force some proseal into the fitting and let it set and then use a drill to make a hole though it?
One step forward two back!
 
That is a known issue. A fellow in our area engineered a special tool that allows you to fix that through the sender hole. I?ll forward a copy of your post to him.
 
You are correct it is the B nut is loose on the inside of the tank it happen on one of my QB wings, its a known problem by Vans ! You have to remove the fuel sending unit and build a special wrench to get to it . Send me a private message with your address and I will send you the one I built.

John
 
Hi Tom. I have the tool to tighten the B nut. I am in Lachute (CSE4), we could meet or I could sent it to you.

Michel
 
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