Quote:
Originally Posted by xcntrk
Do you think it might be a venting or vacuum while pumping problem?
Not sure if your tanks and caps are the same as mine; but I have a problem with both my tanks building pressure as the temp changes. There doesn't seem to be a dedicated tank vent and the gas cap is used to allow vacuum while draining and to relieve pressure, however you have to have the caps in the right position to enable the self-venting.
Try this simple test; Crank the gas cap down tight to where it clicks. At this point you have entirely sealed the tank and it has no vent (from what I can tell). Now, twist the cap counter clock-wise as if to remove it, but stop once you feel pressure from the engagement mechanism. You'll notice the cap will twist maybe a turn and a half before it starts to unscrew. This seems to allow the cap to operate as a vent for the tank.
Whenever I fill my tanks, I perform this procedure and no more venting issues. They must be self-venting caps and screwing them on all the way tight without relieving the venting mechanism prevents them from operating correctly. Good luck!
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I only have a single 30 gallon tank on mine. The tank on mine has the following....the fill line, a vent line that has a hose that terminates up at the area around the fill line surround, a tank vent that goes to the opposite side of the trailer to a charcoal canister (fume/vapor) which makes it comply with EPA and/or CARB for vapor emissions, a suction line that goes to the inlet of the fuel pump (this is where the non-functional check valve was) and of course the top of the tank also has a penetration into it for the level sensor.
Remove the gas fill cap made absolutely zero difference in the flow rate when I was having the issue, and was one of the first things I tried. That led me to believe that there was a restriction somewhere in the inlet side of the system, and there was....a check valve that was not opening fully, which led the fuel pump to not getting enough fuel to pump at the flow rate it should be pumping at....basically starving it of fuel.