Yamaha 40 run for 30-33sek and stops!!

[eddie004]

Hello i have a yamaha 40 2-stroke 3cyl model 1997.
carburators has been cleaned and all the parts inside has been exchanged.
Fuel pump + the hole fuel line is exchanged to new one.
The engine is running for 30-33 seconds and then it stops, then when yuo start it again it starts at once and runs for 30-33 seconds.
And it is the same thing if yuo put on some gas it runs for 30-33 seconds.
What can it be???

[99yam40]

need to test to see if it is losing spark or if it is a fuel issue.

Did you clean and check everything in the carbs and prime start system and follow the steps in service manual for link and sync after reinstalling cleaned carbs?

[eddie004]

Yamaha 40 run for 30-33sek and stops!!

The carburators has been cleaned mechanical and ultra sonic wash.
When i had the boat in water last time i was able to run if i got full speed with in the 30sek but only on full throttle, then direkt when i took of a little bit of gas then it stopped.

[99yam40]

The carburators has been cleaned mechanical and ultra sonic wash.
When i had the boat in water last time i was able to run if i got full speed with in the 30sek but only on full throttle, then direkt when i took of a little bit of gas then it stopped.

could you do a better job explaining what I underlined

And you did not answer my question about adjustments

[eddie004]

The adjustment has been made as in the manual. When i was running with full gas, the gas handel in horisontell, then i only lifted the gas handel for 1 centimeter and the Engine stopped direkt. I am from finland so excuse me I am not so god in English but tank you for trying to help me!!

[Icelander]

Do you have to prime the fuel with the squeese bulb before you get it to run for those 30 seconds?
Could it be the carburetor floats?

[eddie004]

I don't need to squeeze the bulb between the starts. Every time when it has been running for 30 seconds I just start it again and it will run for another 30 seconds.

[99yam40]

sounds like your carbs still have a problem.
Sometimes it takes a couple of times to get is all cleaned up properly.

Make sure you follow the manuals steps for sync and link everytime you reinstall the carbs

[robert graham]

Sounds like a fuel tank venting problem...Run motor with cap off the fuel tank to check....

[eddie004]

Hello
No i have tested to put on a spark indicator and in the same moment when the Engine dies the sparks disappeare, same on all cylinders.

[eddie004]

Does anybody have a clue why it loosing sparks or what I should do next.

[99yam40]

need to measure to see if the charge coil output and pulser coil output voltages going into the CDI are staying in spec or not when problem shows up.

If they are then the kill switch and key switch both ground the ignition to kill the spark, maybe one is going bad or the wiring is shorting to ground

[eddie004]

Hello again no I have measured the output from the charge coil first time it was 200-300 volt and some times it dropped down to 20-30 volt, and all other times it was between 30-40 volt and some times up 60, but it's hard to say if the voltage drops before it dies or if it dies first.
Because the digital measuring device is quite slow.
I haven't measured the pulse coil yet.

[99yam40]

Are you using the proper voltmeter to measure this peak voltage or maybe a DVA adapter with regular meter?
Did you measure on the DC scale?

Did you measure while running or just cranking
loaded or unloaded( hooked to CDI or not hooked up

[eddie004]

I don't know what you mean with proper but it's a cheap one that you can buy anywhere. But tomorrow I'm gonna borrow one from our electrician at work and try again.