Poor running 1968 Merc 20hp

funnyboy

Cadet
Joined
Mar 25, 2005
Messages
14
It was a disappointing test run. I got the motor running in a barrel but tried it in the lake this evening. Here is how it went: <br />-It starts on the 3rd or 4th pull but I have to increase throttle.<br />-Has a weak idle-seems like it needs to be higher.<br />-Runs roughly at mid range and smoothes out somewhat at higher RPMs.<br />-Top speed is slower than the 1978 20hp I also have that runs perfectly.<br />-Seems to occasionally misfire throughout RPM range and if I squeeze primer bulb the motor cuts out.<br />-After shut down the engine weeps fuel at exhaust and carb.<br />-The engine runs warmer than it should....has plenty of tell tale but exiting water is very warm-to hot. Should run cooler.<br /><br />I posted earlier where I indicated I replaced the inlet needle and seat and fuel pump diaphram. Also impellar, lower water pump housing (base).<br />Any additional help very appreciated.<br />Thank you.<br />John
 

Laddies

Banned
Joined
Sep 10, 2004
Messages
12,218
Re: Poor running 1968 Merc 20hp

If the engine cuts out when you squeeze the bulb the inlet is leaking or the float level is to high, as far as the miss it could be rich or pts and cond (ignition) fix the rich problem first
 

Chinewalker

Fleet Admiral
Joined
Aug 19, 2001
Messages
8,902
Re: Poor running 1968 Merc 20hp

The condensers on those magnetos are less than robust - I would replace both as a matter of course, and it may rid you of the missfire...<br /><br />- Scott
 
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