Mercury 40 HP classic ( 4 cyl. ) did lost power while cruising

[Jean Narrache]

Hello everyone !

I just rebuilt this outboard and did a break in period.

Yesterday, i was cruising on my way to a fishing spot, RPM was about 4600 - 4800.
Suddenly the engine had a loss of power, like when you run empty... so i believed that was the reason. Surprisingly i still had way enough gaz to avoid such situation. So i looked at oil gauge in the front cowling and showed little to no more oil. So i added one quart believing that was the reason... Nope ! No changes. Engine start up right on demand but runs rough now, put in gear, gave gaz and something was going wrong, not much power, no way to go over 3000 RPM at WOT... !!!

While doing the break in period, not thrusting the injection pump, i pre-mixed the gaz and the pump did it's job too. So oil mixture is pretty high ! So i believed that the plugs were fouled and then scrapped, so i changed the plugs, but nothing went better with new plugs.

I noticed that voltage was at 15.8 - 16.1 volts... Way too high !!!!!
Could this have damaged someting ?


Thanks,

Mike

 

[Jean Narrache]

Mercury give values in peak voltage to be read while cranking or engine running. This requires a special electronic tool wich is not common.
Suzuki give values in Ohms, to determine if various components are good or bad, this is much easier to test.

Is there any reference values available in Ohms for this engine ?
For Stator, trigger, coils and voltage regulator.


Here is a small video of this engine running strong, when i did installed it on my fishing boat two weeks ago.
This is in french, because i am born french speaking and was made for a french boating forum.
You will notice that it smokes quite a bit... of course ! as i didn't know the reliability of the oil injection pump, i did not risk to blow this engine just rebuilted, so i did run it with 50:1 pre-mix gaz and the pump does work too and it is mixing to 50:1 too, so the gaz / oil mixture is at 25:1 no problem about oiling here... it won't have ceasure problem.

https://youtu.be/VBOUbX0aeWQ

​Thanks !