I redid my fuel system a few years back and upgraded to an electric fuel pump. Since then after my Spryte sits for a week or more, the starter has to run 10 seconds or longer before the engine fires up. I figured out the carburetor drys out after about that long and it takes at least 10 seconds for the electric fuel pump to push fuel to the carb. Rather than have to run the starter for 10 seconds, I want to add a switch to run the fuel pump a bit before I try to start the engine.
I did a test run of this idea this weekend. The cat had not run in over a week. I hot wired the fuel pump for a bit and then tried to start the engine. It fired right as if it had just been turned off.
So, I installed a momentary push switch in dash. I ran a wire from the ignition switch (this wire is only live when the ignition is on) to the new push switch and then from the push switch to the wire that supplies power to the fuel pump. Turn key on, push the button, and power goes to the fuel pump. Great! Well almost - one problem, there is another power line that goes to the fuel pump form the oil pressure kill switch. When there is no oil pressure, this switch connects the wire on the starter switch to the fuel pump so the pump runs during starting. (It also supplies power to the pump when there is oil pressure.) Now when I push the primer button power also goes to the starter switch and the starter cranks. I need to keep power from going down the oil pressure kill switch to the starter. I thought about putting a diode in the wire between the starter and oil pressure switch. This should keep the starter from firing when I use the prime button. Has anybody done anything like this? Does anybody have a better idea?
I did a test run of this idea this weekend. The cat had not run in over a week. I hot wired the fuel pump for a bit and then tried to start the engine. It fired right as if it had just been turned off.
So, I installed a momentary push switch in dash. I ran a wire from the ignition switch (this wire is only live when the ignition is on) to the new push switch and then from the push switch to the wire that supplies power to the fuel pump. Turn key on, push the button, and power goes to the fuel pump. Great! Well almost - one problem, there is another power line that goes to the fuel pump form the oil pressure kill switch. When there is no oil pressure, this switch connects the wire on the starter switch to the fuel pump so the pump runs during starting. (It also supplies power to the pump when there is oil pressure.) Now when I push the primer button power also goes to the starter switch and the starter cranks. I need to keep power from going down the oil pressure kill switch to the starter. I thought about putting a diode in the wire between the starter and oil pressure switch. This should keep the starter from firing when I use the prime button. Has anybody done anything like this? Does anybody have a better idea?