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40hp 2 stroke 2004 starting issues

M

molson

New member
hello
go the boat out this spring got the motor running with no issues...went to the lake and it wouldn't start.. had to turn the prime assist switch on the right side of the carbs...it then would start up fine...not sure what to replace...the diaphragm for the prime assist, or the prime starter assy. which runs $180. (how do I test it) ..after it has been running I put the switch back to its original position and it dies. Stays running with the switch on.........runs fine when it runs.
thanks or your time
 
The procedure for testing the prime start is to measure the length of the plunger, apply power to the plunger (positive to plug, negative to black) for five minutes and then measure the length of the plunger again. It should be no less that about 25mm on my motor (a 50 HP).

If this problem has occurred after motor sitting for the winter I would also consider cleaning the carburettors: https://youtu.be/ye_Ui9D8dBE

Stuart
 
DangarStu said:
The procedure for testing the prime start is to measure the length of the plunger, apply power to the plunger (positive to plug, negative to black) for five minutes and then measure the length of the plunger again. It should be no less that about 25mm on my motor (a 50 HP).

If this problem has occurred after motor sitting for the winter I would also consider cleaning the carburettors: https://youtu.be/ye_Ui9D8dBE

Stuart
Click to expand...
Thanks for the reply....it ran good with no problems when I pulled it out of storage.....at theake it wouldn't start....always use sea foam and fresh gas.....thought I might of had a primer bulb go bad but it started working...
At the lake it flooded a bit..didn't try the prime assist switch til the next day.....
What exactly does the prime starter do? I'm not familiar with out boards...
I'll test test it when I get off work...
Thank you
 
The prime start system makes the mixture richer by spraying a bit of fuel into the intake manifold, a bit like an accelerator pump. I guess the idea is that while it is not in operation it doesn't present as much of an airflow obstruction as an open choke, but personally I've always found chokes more reliable. If a motor has an accelerator pump, pushing the throttle all the way open three or four times can also force enough fuel through the pump for the motor to start.

Stuart
 
DangarStu said:
The prime start system makes the mixture richer by spraying a bit of fuel into the intake manifold, a bit like an accelerator pump. I guess the idea is that while it is not in operation it doesn't present as much of an airflow obstruction as an open choke, but personally I've always found chokes more reliable. If a motor has an accelerator pump, pushing the throttle all the way open three or four times can also force enough fuel through the pump for the motor to start.

Stuart
Click to expand...
OK that makes sense now....they are using that as my choke...correct?
Now what does the switch do? Bypass the diaphragm? And would that mean its bad? Like a diaphragm gas pump on a riding mower?
Just puzzles me how this would happen in just a short time...that switch diverts gas from going to the carbs and dumps it in the intake?...hate to think the carbs are plugged as careful as I am with storage....
I appreciate your answers as it is rough to find someone knowledgeable on these motors.
 
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