merc 70 bad starter

tony murray

Cadet
Joined
Jan 7, 2009
Messages
19
i have an 3cyl 70 merc blueband, which is a pain to start.\

iv changed all the fuel lines.....primer bulb.....fresh fuel........spark plugs.......it will fire up if i spray a fuel mix direct into the carbys but it will only run while it burns that fuel

its sat for a while but prior to that it ran fine

any ideas anyone

thanks
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,030
Re: merc 70 bad starter

Sure, sounds like clogged carbs. The idle passages will clog if it sits too long. Time to disassemble, clean and rebuild carbs with new gaskets and inlet needle and seat. Inspect carb floats. If they are partially disolved or cracked, replace them as well.
 

cr2k

Captain
Joined
Mar 19, 2009
Messages
3,730
Re: merc 70 bad starter

Chris1956 you passed right over the fuel pump. Will it start/run while you are squeezing on the primer bulb?

Pull the fuel line at the carb or off the outlet of the fuel pump and squeeze and see if you are getting fuel that far. If not go one step back (inlet to the fuel pump), then another, etc. until you get fuel.

I guess the title of your post should be Bad Starting
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,030
Re: merc 70 bad starter

CR2K - That motor will run a couple of minutes if the fuel pump is non-functional, once you pump the carbs full. If it only runs a few seconds, the carbs are not supplying any fuel. This means the idle passages are likely clogged, the floats are stuck closed or the carb idle mixture is misadjusted.
 
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