1986 Merc Black Max (No Power Under Load)

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Melton88

Recruit
Joined
Jul 17, 2002
Messages
4
Fellow boaters Good Day. I have a 1986 Mercury Black Max that is having a frustrating problem. Motor runs fine at idle/high idle. When under load however it runs rough wont top 2000 rpm at full throttle and seems to be hunting or surging like its trying to rev up. I can take it to the lake in the morning and this is whats strange for the first 4 or 5 minutes it will run at top speed and then just fall off on RPM and Troll from there. I hope this was not to long a post. Thanks guys for your help in advance.<br />Melt.
 
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Melton88

Recruit
Joined
Jul 17, 2002
Messages
4
Re: 1986 Merc Black Max (No Power Under Load)

Hey guys its a Merc Black Max 150...Melt
 
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AndyL

Petty Officer 1st Class
Joined
Jul 1, 2002
Messages
307
Re: 1986 Merc Black Max (No Power Under Load)

G'day Melt,<br /><br />Have a look at the plugs, probably the cheapest starting point and see if they all look like they are firing. If any are a strange colour or very oily your problem could be simply they need changing. Of course ther could be something more sinister but my Black Max eats plugs at an alarming rate and when they go it produces problems similar. A new set of plugs and the engine is like new for a while. If they look OK check your fuel pump or try priming manually while demanding power to force the fuel into the system.<br />Good luck.
 
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billnsherisboat

Cadet
Joined
Mar 8, 2009
Messages
8
Re: 1986 Merc Black Max (No Power Under Load)

i have a 85 black max did the same thing spent money on carbs and plugs ended up being my stator was only putting out half the voltage it was supposed to get it checked first or you will running in circles trust me
 
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