Good retrofit for older carbureted applications
My old lawn tractor quit running the other day. I diagnosed it as a fuel delivery issue (it would run-- barely-- on full choke or with some carb cleaner sprayed into the engine) and figured out that the diaphragm fuel pump that runs off the pressure pulses inside the engine crankcase was not delivering much fuel. This pump is built into the side of the carburetor and the parts for it come in most rebuild kits. The trouble is, I'd already rebuilt the carburetor and fuel pump. I concluded that the pressure pulses going to the pump were a bit weak, either because the engine is getting tired or the crankcase has a leak somewhere or both. Since the engine runs very well and doesn't smoke, I decided a brute force approach was the best course. I'm good at those so I was already on familiar ground. For $10 I got this pump, and for another $12 I got a 4-pack of relays with mounting pigtails. I had some ATC fuse holders, wire, crimp connectors, etc. already. I figure this repair cost me about $25 in parts plus an afternoon of my time. I wired the relay to the hot side of the battery with an inline fuse, then wired the control side to a switched power wire from the starter switch. When I was done, the pump would only run when the key was on. Perfect. I made a mounting plate out of a piece of aluminum I had kicking around, plumbed the fuel line with a new filter and shutoff valve, zip-tied all the wires out of the way, and turned the key on. The pump cycled and filled the float bowl of the carburetor. I twisted the key to the start position and the engine roared to life. I managed to finish mowing my lawn and the tractor worked fine the whole time. This pump is a good low-cost solution for fuel delivery issues on old machines. No idea what the longevity is but for $10 if it lasts a couple of years I'll be thrilled. It's a very good idea (translation: essential) to run the pump with a fused power feed and a relay or some other means of shutting it off. Running without a fuse is an accident waiting to happen if a wire shorts out somewhere so don't skip this step. You could probably run the pump on a switch but a relay with key-on power is almost as simple and there's less danger of forgetting it on and killing your battery (or worse). I'm not sure what the max pressure of this pump is, but keep in mind that the needle valves in some small engine carburetors may not withstand it. If the pump overpowers the needle, it will overflow the float bowl and flood the engine. At that point you'd have to install some sort of bypass or regulator to return excess fuel back to the tank. This didn't happen to me so I didn't investigate. Take note of the dimensions of the pump before ordering. Those mounting legs and the hose barbs stick out a surprisingly long distance. I had trouble finding a place to mount the pump until I found a small area under one of the engine's cylinder heads. This proved to be a good spot because the inlet of the pump will gravity feed, but there were a few other spots I tried where the pump absolutely would not fit. This pump is available from a lot of different sellers on Amazon. I bought the one that had the best combination of low price and good reviews. Fingers crossed, it appears to be relatively trouble-free. I'm cautiously optimistic. Read more
