'70 Merc 90 quits under load

[tomfriedman]

Engine idles and revs well in neutral. When the prop is out of the water (with "ear-muffs" on), the prop spins well in forward/reverse. When the prop is in the water, motor dies when put in gear. Motor will keep running if put in gear at high revs, but not a good experience. Timing, compression good & new filter/plugs. Don't know the history, but last owner said it ran well, but he put on a new prop on before selling it. Thanks in advance!

 

[JB]

Re: '70 Merc 90 quits under load

Hi, Tom.<br /><br />Power loss is a very common problem. Most outboards seem to start, idle and rev well with no load on only one cylinder.<br /><br />There is a lot of troubleshooting advice for this problem on www.outboardrepairs.com Look up power loss.<br /><br />If that doesn't lead you to the cause, come back to this thread and we'll give it another try.

 

[tomfriedman]

Re: '70 Merc 90 quits under load

Thank you JB. A little digging at http://www.outboardrepairs.com/ is pointing me to the idle circuit... Thanks for the advice.