1985 mercury 850 just quits.

[sillychap]

I have just had my 1985 850 rebuilt by a shop and have only run it twice since the rebuild. It starts fine but after a few minutes will quit like some one shut off the key. It will start back up imediately and the process will start all over again. (this occurs at fast speeds and at slow) I have had it sitting for awhile since the rebuild but started it every month till I could find the time to take it out. I have also found it to run much louder than before and with a more matalic sound to it.(don't know if these are related)Have done no work on this moter myself but have rebuilt a johnson 115 before this one. Thanks for all your help in other postings.<br />Sillychap

 

[12Footer]

Re: 1985 mercury 850 just quits.

Wecome to iboats.Not much to go on, but i'll give you some primary checks to perform.<br />Compression test first off. Nothing's going to happen with low compression.<br />Second, when it quits, let it cool enough to pull the plugs, and check thier condition. they will tell you at least which cylinder is doing what, and let you know if you have water getting into the cylinder.<br /><br />Make sure it is cooling properly. If not, it may be trying to save itself, by shutting down. Some engines are equipped with a thermal cut-off sending unit, and some have overtemp rpm limitters. I don't think your make/model motor has iether, but check in the manual for it.<br />Drain the carb bowls, and inspect for water. check for water floating at the bottom of your fuel tanks too.<br />The symptoms here would be ; runs fine, until you hit a wake or wave, and it gets a drink of carb-suplied water, and shuts-off, as if you pulled the lanyard. The injested water then quickly evaporates in the hot cylinder, and she starts right back up.<br />Good luck.