72 merc 80 hp hard starting

[CharlieB]

Re: 72 merc 80 hp hard starting

If the choke plates are closing while cranking yet the motor STILL needs fuel added to start, then it is time to get into the carbs and see what the float levels are, they may be a bit too low and making it difficult to pull fuel at cranking speed. With higher RPM running it isn't near as critical, check the floats, while you are there clean everything.

This is also still assuming that cranking speed is at 300 RPM or better, other wise a slow cold cranking can contribute to hard starting.

 

[Chris1956]

Re: 72 merc 80 hp hard starting

That motor has a battery powered CDI System. You might like to check battery voltage on the red and white adjacent wires on the switchbox, while cranking. Maybe the ign wire (white) has some resistance, lowering voltage to switchbox while cranking?

 

[turboapache]

Re: 72 merc 80 hp hard starting

It cranks at 500 or so, and the voltage is good. Batteries are fully charged.

 

[Chris1956]

Re: 72 merc 80 hp hard starting

OK, What is the voltage at the switchbox?

 

[Chris1956]

Re: 72 merc 80 hp hard starting

While cranking the motor?