Fuel pump question.

[SCORPIO]

My bee engines came with Carter electric fuel pumps. When first installed, the pumps would prime the carbs when the key was turned to the run position. This year, they dont do that. I have to crank the engine 10 seconds or so to build some oil pressure then the pumps run and engines start. I replaced the three wire Hobbs switches that give low oil pressure shutdown protection but that made no difference. It's not really a problem, more of a mystery as to what changed. I liked the prime feature, made the engines start like fuel injected motors.

 

[Bt Doctur]

Not how it works, when the key is turned to start the starter solenoids outer post powers the fuel pump, when the engine starts the oil pressure switch powers the fuel pump

 

[scoflaw]

Another broken wire probably

 

[SCORPIO]

Another broken wire probably

But on both engines?

 

[SCORPIO]

Not how it works, when the key is turned to start the starter solenoids outer post powers the fuel pump, when the engine starts the oil pressure switch powers the fuel pump

Got any suggestions on where to look for the issue? The wires are on the R terminal of the starter on both engines and I haven't done anything with them since last year. Like I said, a mystery, and I'd like to solve it.

 

[PlayDate]

I'm curious about this.

This is how your oil pressure switch works:

The Carter A68301 pressure switch is a single pole double throw diaphragm actuated switch. Start and Pump terminals will be active during cranking and the ignition and pump terminals will be active when 7psi of oil pressure or higher exists. All current will be deactivated if 7 plus pounds of oil pressure or the start switch signal is not present. With a 10 Amp rating across the entire switch.

So the ignition key basically bypass the oil switch by applying voltage during cranking to energize the fuel pump relay. There is no 5 second "priming" as you have with modern day fuel injection. Normally, I install momentary prime switches at the helm to move fuel to the carburetors before turning the key. The momentary switch sends 12 volts the the Yellow wire connecting to the relay and energizes the fuel pump. This really helps when the boat has been sitting for a while.

Depressing the momentary switch for 5 seconds basically moves fuel into the fuel bowls for an easier start.

I'm sure someone makes a relay with a 5 second activation but I haven't used one.