What goes on inside the Primer Solenoid?

[cfauvel]

what does the primer solenoid actually do? I hear it clicking when I push the key in and out, but not what is going on in there.

is it a pump of sorts? does it pump with each push of the key? or does it pump as long as the key is pushed in?

Why is it associated to "choking " your engine?


thanks

Chris

 

[ezeke]

Re: What goes on inside the Primer Solenoid?

The solenoid is an electromagnet with a steel rod in the center.

In the case of the primer solenoid, when voltage is applied to the electromagnet, the steel rod opens the valve that allows pressurized fuel to pass through and be injected directly into the intake manifold, effectively bypassing the carburetor.

The primer solenoid is just a valve; the pressure comes from either the primer bulb or from the fuel pump. If you are not cranking the engine, the fuel pump does nothing because it relies on the movement of the pistons.

In earlier engines, choke plates activated by solenoids closed the carburetor throat to block air flow and force the pistons to pull more gasoline into the intake. This enriched the fuel/air mix, making it easier to start a cold engine.

Either primer solenoid or choke plates enrich the fuel/air mix and so do the same thing.

 

[Dhadley]

Re: What goes on inside the Primer Solenoid?

It's basically an electric valve, not a pump. When you pump the primer bulb you create pressure in the fuel lines and fill the carb bowls. When you activate the electric primer solenoid it opens a passage and fuel goes into the intake area. As you lose line pressure the fuel quits flowing. That fuel primes the motor. Without re-pumping the bulb or starting the motor, no more fuel will flow thru the open valve.

 

[Dhadley]

Re: What goes on inside the Primer Solenoid?

Sorry E - you type faster than me.........

 

[cfauvel]

Re: What goes on inside the Primer Solenoid?

Excellent guys, thanks that makes sense now...and makes sense why some say hold the key for longer periods when trying to cold start the motor.

 

[Dhadley]

Re: What goes on inside the Primer Solenoid?

If the motor isn't running or someone isn't squeezing the bulb only so much fuel will be released no matter how long you hold the key in. That's why it's so hard to flood a motor with that system.

 

[tashasdaddy]

Re: What goes on inside the Primer Solenoid?

but you can flood it,especially if you have a weak battery, the motor has to turn +- 300 rpms with the starter, for it to start.