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1986 28sp Johnson electric primer question

N

notyepcars

New member
Having problems getting my 28hp Johnson running. I put a carb kit in and broke off the nipple on the carb from the primer. Anyways, started ok and bogged down as usual and restarted, for the hell of it I held the primer hose and sprayed the fuel directly into the carb and the boat ran great. I have two questions. 1. Does that primer pump fuel at all once you let off the key? I was surprised it still squirted fuel with letting off the key. 2. If I ground one of the wires on the primer solenoid and touch power to it, it clicks once, is this normal? Thanks
 
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(Fuel Primer Solenoid Function)
(J. Reeves)

The RED lever...... The normal operating/running position is to have that red lever positioned over top of the solenoid and aimed at the other end of the solenoid, gently turned to its stop. This is the normal/automatic mode position. Pushing the key in opens the valve within the solenoid allowing fuel to pa$$ thru it in order to prime and start the engine. Looking upon this solenoid as a electric choke results in a better understanding of it.

Having that red lever turned in the opposite direction, facing away from the solenoid, allows fuel to flow thru it to the crankcase area. One would only turn the red lever to this position in a case where the battery might go dead and the engine had to be started via the rope pull method. Look upon putting the red lever in this position as moving a choke lever on a choke equipped engine to the full closed position. Either one would supply fuel to the crankcase/engine for starting purposes BUT if left in that position while running would flood the engine.

The later model primer solenoids are equipped with a schrader valve, used for attaching a pressurized can of fogging oil etc, available at your local dealership with complete instructions.

Pumping the fuel primer bulb up hard fills the carburetor float chambers of course, but that process also applies fuel pressure to the primer solenoid.


The two small hoses leading from the primer solenoid branch off via tees to each fuel manifold section that would feed fuel to the individual cylinders.


Pushing the key in activates the primer solenoid to allow fuel to flow thru it to the intake manifold pa$$ageways. Cranking the engine over causes the fuel pump to engage which in turn sends fuel pulses to the primer solenoid via the 3/8" fuel hose.


Some engines incorporates the "Fast Start" feature which automatically advances the spark electronically so no advance of the throttle is required for starting.
Engines that do not have the "Fast Start" feature will be required to have the throttle advanced slightly.


Starting procedure: pump fuel bulb up hard, crank engine and push the key in at the same time. When the engine fires/starts, release the key so that it falls back to the run position.


Bottom line..... Look upon the primer solenoid as an electric choke.
 
So this is in the normal position, activated by pushing in the key? If the motor is idling and I pull off the fuel line, I should not be getting fuel out the primer solenoid?
 

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yes that is the correct normal position to leave the solenoid in for when pushing in the key.

I will try and explain it a different way than Joe does, he is 100% correct of course, but this might help you.

when you have the motor running the fuel pump still sends pressurised fuel to everything, inc the solenoid ,but without the key pushed in the valve is kept closed so
no fuel enters engine from the solenoid.
if you pull a pipe off the solenoid fuel will come pouring out of it because it is getting that direct from fuel pump ....need to plug the pipe if nipple is broken ...

imagine a fuel line going from fuel pump direct to the crankcase, fuel would keep going in all the time the fuel pump is working.
Now cut that pipe and put in stop valve, this is the solenoid...it only opens when you push the key in !!!! without pushing in the key the valve is shut, this then lets
the carbs do their job an only them sending fuel to the crankcase.

When the red lever is turned up the valve is open for manual starting, then you need to hurry up and close it or will flood like Joe has said above.

i used to think it was like a small electric pump, it is not, it is simply a solenoid that opens to let fuel pass by.
this is also why you only hear the one lick, it is the plunger inside opening quickly.

hope that helps...
once you get the drift of this you can see that Joe is bang on the money with his explanation, but he forgets we are not all outboard Guru's like him ha ha
 
Last edited:
notyepcars said:
So this is in the normal position, activated by pushing in the key? If the motor is idling and I pull off the fuel line, I should not be getting fuel out the primer solenoid?
Click to expand...

Yes, that is the normal, running position.

The larger hose of the three is the fuel supply hose (pump to solenoid).

The two smaller hoses supply fuel to the engine "ONLY" when the key is depressed. Otherwise, nothing should be coming out of them regardless of the engine's rpm..
 
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