Help with air in fuel tank of oil burner after filling

[williamthomas]

We run a animal cremation oil burner that uses the same type of oil burners as oil burner heating systems. We have an issue with our system that every time we have our fuel tank filled we can not run the burners for 2 to 3 days. They back fire & sputter. If you try to bleed the fuel lines through the burners it is nothing but foamy fuel. We have a fuel filter after the fuel tank then everything runs through copper lines to the fuel pumps on the burners. I can not figure out why when the tank gets filled why we get so much air in the lines & have to wait days for it to settle before we can get it to run correctly. Any thoughts, suggestions, ideas? The tank sits on the ground this is an outside system. Both oil burners have their own feed lines & return lines. All connections have been checked for tightness & leaks. Thank you in advance.

 

[bullfrog]

Do you fill it before it runs low on fuel or till it quits? Letting it run completely out will cause air to get in the system and as it most likely uses a pump to inject the oil into the burner it will become air locked or have air trapped between the pump and the injector. Also when filling the tank do you pump or pour in the oil? Pouring slowly to keep air out of the oil when the tank is half full should solve the problem as long as you never let it get below 1/2 full. Having a vented tank as the highest point in the system gives the air someplace to go other than the pump. If your tank is the lowest point in the system the lines may be draining back into the tank causing air to get into the system. You may need to install a one way valve (check valve) to prevent that from happening at the pickup line where it comes out of the tank and goes to the inlet of the pump. If you already have one it may be defective.