High pressure on Racors

[dennismenace111]

Why not try to just temporarily bypass your Racor filters! Eliminate one potential problem point!

[svspirited]

First off, thanks to everyone that replied. Some useful tips. I figured out the problem today and it wasn't anything I expected it to be. To trouble shoot I removed the fuel line feeding the engine just to see what kind of flow was coming from the lift pump, nothing more than a trickle. I bypassed the filters altogether and the stream was fine. So of course I figure it is something in the filter system. Turns out that was wrong. The filters and everything in the racor system was clean as a whistle. So, what other common component is there? The three way valve that directs the fuel from the filter to either the engine or the polishing pump so I bypass that and everything starts working all peachy keen like. Never would I have suspected that valve!

[Lepke]

If your lift pump and polishing pump have valves (diaphragm type pump) you don't need the 3 way valve or any valve. The internal pump valves act as check valves, only allowing the fuel to travel in one direction. Both pumps can run at the same time (as long as fuel lines are sufficient).

[captnknopf]

There is a check valve on the 500 series Racors. It is a ball maybe with a spring. I have had them stick causing a high vacuum. If you are getting up to 15 inches, it is not surprising to get some air in from the square gasket. there is obviously a plug between the check valve on the Racor and the valve switching between tanks, as all tanks have the same problem. Check for a plug at the three way valve to the tanks. You can disconnect different pipes along the way with the polishing pump running and put your finger over the pipe to see if there is suction. when there is no suction, you have found the problem