eyemon
New Member
My research has uncovered numerous workable ways of wiring an aftermarket electric fuel pump with some being pretty simple and others not so much. My post isn't intended to disparage other's wiring designs but I didn't find any that fit well with what I wanted to accomplish. I wanted to be able to do a number of things all with a simple operation of the ignition switch and without adding an extra manual on/off nor instantaneous switch. I don't pretend to be any kind of wizard, but what I've come up with
lets me prime the carburator and fuel system for as long as may be needed, temporarily bypass the oil pressure safety switch for a pre-determined length of time, start the engine, and then have the electrical power to the fuel pump automatically change its route from through the temporary bypass to
only through the oil pressure safety shut down switch.
Everything mentioned above happens with a turn of the ignition switch. It is a simple and trouble free
answer to an aggravating problem that we experience with our classics that may sit for days or even months unstarted, during which time the fuel in the carburator float bowls can mostly evaporate. In fact, fuel evaporates rapidly also after shutdown of a hot engine as is evidenced by the need to engage the starter longer that normal after only a few hours of hot engine shutdown. I want my engines to always start on the first or second revolution but suffered along for "many moons" before coming up with the kind of fix that was what I wanted. I'm happy to pass my design along to all who may benefit from it. A shortened explanation is that the electric pump powers up instantly with the ignition switch being placed in the "run" position and is left in that position long enough to let the pump replace what gas has evaporated, before then engaging the starter. I've added an adjustable (on or off) delay relay
(also powered up when the ignition switch is placed in "run") into the electrical supply to the fuel pump. I've set that relay to 45 seconds which is the length if time that relay pin #87 powers up, sending 12 volts directly to the pump before #87 de-energizes. That 45 seconds (can be set longer or shorter) gives plenty of time, in my case, for the pump to refill the float bowls and for me to turn the ignition key to "start" which in turn fires up the engine, closing the oil pressure safety switch, thereby "taking over" all power supply to the fuel pump after the time delay relay pin #87 de-energizes. The wiring is such that the adjustable relay be set so that there is some number of seconds of "overlap" after the engine actually starts and before the #87 pin shuts off.
As in earlier posts I haven't learned yet how to get my messages over in fewer words, but I'm working on it. I have detailed additional information, including particulars about the adjustable timer delay relay, as well an easy to understand wiring diagram that I would forward by USPS to anyone who might want that information. (the referenced info is on hand written sheets and I have no idea of how to do that kind of thing electronically and no one to show me)
lets me prime the carburator and fuel system for as long as may be needed, temporarily bypass the oil pressure safety switch for a pre-determined length of time, start the engine, and then have the electrical power to the fuel pump automatically change its route from through the temporary bypass to
only through the oil pressure safety shut down switch.
Everything mentioned above happens with a turn of the ignition switch. It is a simple and trouble free
answer to an aggravating problem that we experience with our classics that may sit for days or even months unstarted, during which time the fuel in the carburator float bowls can mostly evaporate. In fact, fuel evaporates rapidly also after shutdown of a hot engine as is evidenced by the need to engage the starter longer that normal after only a few hours of hot engine shutdown. I want my engines to always start on the first or second revolution but suffered along for "many moons" before coming up with the kind of fix that was what I wanted. I'm happy to pass my design along to all who may benefit from it. A shortened explanation is that the electric pump powers up instantly with the ignition switch being placed in the "run" position and is left in that position long enough to let the pump replace what gas has evaporated, before then engaging the starter. I've added an adjustable (on or off) delay relay
(also powered up when the ignition switch is placed in "run") into the electrical supply to the fuel pump. I've set that relay to 45 seconds which is the length if time that relay pin #87 powers up, sending 12 volts directly to the pump before #87 de-energizes. That 45 seconds (can be set longer or shorter) gives plenty of time, in my case, for the pump to refill the float bowls and for me to turn the ignition key to "start" which in turn fires up the engine, closing the oil pressure safety switch, thereby "taking over" all power supply to the fuel pump after the time delay relay pin #87 de-energizes. The wiring is such that the adjustable relay be set so that there is some number of seconds of "overlap" after the engine actually starts and before the #87 pin shuts off.
As in earlier posts I haven't learned yet how to get my messages over in fewer words, but I'm working on it. I have detailed additional information, including particulars about the adjustable timer delay relay, as well an easy to understand wiring diagram that I would forward by USPS to anyone who might want that information. (the referenced info is on hand written sheets and I have no idea of how to do that kind of thing electronically and no one to show me)
