Mercury 40hp - 1980 - Starting problems

[Silverlion]

I recently bought a Mercury 40hp (black) with electric starter. Per Mercury mechanic engine has good compression but is hard to start at times (Cold mostly, sometimes when hot). Have replaced stator. Real hit & miss. Somtimes starts and somtimes not. Motor mounts have standard wear and are not leaking exhaust into carb intake. Suggestions please.

 

[12Footer]

Re: Mercury 40hp - 1980 - Starting problems

It may have low compression,so check this first off. With low compression, the fuel pump wont pump fuel, the fuel pumped won't be injected and compressed ,and finally, exaust not expelled eficiantly.<br />While you have the plugs out for the compression test, inspect thier condition. That will give you a good picture of what is missing in the fuel/fire/breathing equation.<br />Let us know what you find.

 

[Silverlion]

Re: Mercury 40hp - 1980 - Starting problems

Thanks, 12footer. The mechanic that is helping me has been down that path and all checks out ok. Any additional suggestions????<br /><br />Thanks!

 

[12Footer]

Re: Mercury 40hp - 1980 - Starting problems

I must be getting old..I'm sorry,you did say that it had good compression...When it does this, pump the primer ball a couple times to see if it is firm,or whether it pumps more fuel to the carbs.<br />If firm, try squirting a 3 second blast of WD40 into the carb. and see if it starts quickly.<br />Does it tend to run better out of the water,than it does in the water? If so, It might have a clogged exaust port. The reeds are good, as you described, but this would be a sign the it's not expelling the exaust as it should.<br />Is the spark weak, or strong? It should be blue,not yellow at the plugs.<br /><br />When it does start, how does it run? Any missing or sneezing?

 

[Silverlion]

Re: Mercury 40hp - 1980 - Starting problems

12Footer: Once it is started the engine runs well. Sometimes during long idel periods it will cut off but overall runs well. Spark seems strong but I will check the color. I will try all of your suggestions and see if it cures my problems. THANKS FOR ALL THE HELP.

 

[12Footer]

Re: Mercury 40hp - 1980 - Starting problems

Look also for small leak in the fuel line. It must be air-tight. Does the fuel line have an inline filter?