Originally Posted by Chotu
Lots of experience here with fuel pumps. I think my add on question is on topic.
I have 3 fuel tanks down in the hull
of a catamaran
. There are uninterrupted fuel lines from each tank to a set of valves to select the tank in use. These valves are located in the propane locker. (Gasoline)
Immediately after these tank selection valves is the Facet diaphragm fuel pump. After the fuel pump is a Racor
fuel/water separator and filter.
From the filter, the fuel line is teed (again all is in the propane locker at bridge deck level) and a line runs to each outboard
Facet pumps are incredibly loud. Sounds like a machine gun. Is that normal?
Pump loses its prime very quickly when off and gasoline goes back to tanks.
Pump really struggles to get fuel to the engine. Takes 10-30 seconds to pull fuel up from the tanks.
Pump cannot push fuel up to bridge deck roof level.
Whatís wrong with my installation
I am not familiar with your particular diaphragm pumps. If they are of any size, I'm going to say that you have one of three problems:
1.) The ends / bearings on the pushrod that flexes the diaphram are worn causing the noise
. This could also be the joint that connects the pushrod to the diaphram.
2.) The pump check valves are shot. They could be cracked, or have a build up of sludge on them causing them to not close entirely. This will affect the height that the fuel can pumped to and also explain the gas not remaining at the engine...leaking back to the tanks.
3.) Your diaphram may not be seated properly in the housing, causing some
of the push pressure to be lost
If it was me, I'd do a quick tear down and inspection
of all the bits and pieces. This is not a hard job if you have spares on hand.
I am asking myself why you have diaphragm pumps for this service
. If I understand your system description, this is not an engine mounted pump, but rather a bulkhead mounted pump in a locker. You could get a rotary pump for this service
. They would be quieter. Since it is gas, if you go rotary, you may want one that is magnetically coupled. Then you wouldn't have to worry about a shaft seal
If your diaphragm pump is one of the really small ones, the same problems may exist but you probably can't rebuild
it. Just replace it.