Re: Fuel pump and filter mystery

I just learned more that bears on some of the previous replies.

I disconnected the wire from the priming pushbutton switch to the Stewart Warner Model 235A-D fuel pump and held a light bulb in the circuit. When I pushed the button, the bulb lit and the pump ran briefly. When the pump stopped, the bulb brightened. There is no pressure switch. The pump simply stalls. Why I couldn't get it to run after changing the first filter element with the housing open so the pump was not working against any pressure remains a mystery. Why the pump started working again and continues to work is another mystery. There are two separate electrical paths to it so it was not an electrical connection problem on the positive side. The negative side connections were solid.

I know from previous experience when I accidentally knocked the fuel tank shut off closed (now secured with cable tie) that the pump makes a loud clacking noise and does not shut off when the supply line is closed. A clog at the tank suction isn't likely.

The engine driven pump squirts fuel out when the line on the post secondary filter side is cracked. The oil level is exactly where it was last time I checked and there is no fuel in the bilge so a problem with the engine driven pump is now a very remote possibility.

Looking more critically at the fuel system, I see that the electric pump was probably put in to accomodate a rather silly hose run intended to make everything look neat at the boat show. The bottom of the tank is above the engine driven pump so I'm going to reroute it to eliminate the high spots and make the electric pump less critical although I will keep it for priming and bleeding.

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Roger Long


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