Please help a Rookie (slightly long)

[pittspilot]

Hi, I have a 1973 Mercury 200 20 HP Motor, Serial number 3758866. Soon after purchase (it came with the boat) it began to have running issues. What would happen is, that after a period of running at WOT, and then idling, the motor would die. The motor would then become impossible to start. It could be done, if you used the choke, added about half throttle, and then quickly close the choke once the motor fired. The problem started intermittently, and then became so bad that the motor was dying at low throttle settings. (And making a ticking noise as the motor died down). The fuel used was 89 and new fuel. I had replaced the sparkplugs, going from Champion to NGK, after pulling the plugs and seeing how old they were.<br /><br />I have now taken apart the Carb and rebuilt it, and the motor will not start at all. The bowl gets fuel, I replaced the float, I set the float (I had to eyeball it with a tapemeasure), I checked to see if each jet was clean, I set the idle needle back where I found it. I replaced all the gaskets, (except for the diaphram) <br />Since this is the first Carb I have rebuilt, what would be the errors you would tell a newbie to check for at this point.<br /><br />When I get home, I intend to check the ignition and compression to see what those are.<br /><br />One more thing. When I went to lubricate the lower unit, I had alot of white colored water come out of the hole, and the screws were missing thier washers. The unit has been lubricated and the washers replaced.<br /><br />Please help, and pointers no matter how obvious would be appreciated.

 

[ewaltb]

Re: Please help a Rookie (slightly long)

pittspilot - I know the milky color from the lower unit is water getting in. Most likely from the missing washers. You can pick them up at any dealer. It is amazing how much water gets in with the missing washers. Happened to me.<br />As for the engine not starting after the rebuild, there are others on the forum that might be more knowledgable. I had a very similar issue with my engine, but the carb rebuild solved the problem. Do you have a manual? Believe me, others on the forum are going to ask. <br />I think you are on the right track though, checking the compression. Timing is another issue I think you might want to check. Once you put the carbs back on you need to make sure they are synced up together, and that it creates the proper timing advance. <br />Hope this helps some.

 

[pittspilot]

Re: Please help a Rookie (slightly long)

Yep, this was all done as I studied my manual. There is no way I would have done it without the manual.

 

[Hooty]

Re: Please help a Rookie (slightly long)

Check the plugs and see if you're getting fuel. They should be wet. If they're not, you're not getting fuel.<br />If you have fuel, check next for spark. The spark should jump a 7/16" gap on the way to the sparkplug. If you have both. the only things left are air and timing and the timing should be covered in your manual.<br /><br />g'luck & c/6<br /><br />Hooty

 

[steelespike]

Re: Please help a Rookie (slightly long)

My guess is the floats are set too low.Not enough gas in bowl.Spray some WD40 in the carb If it starts its a fuel problem. If you have adjustable high and low speed jets adj. low speed <br />1 1/2 turns from bottom (gentle)high speed 3/4 turn from bottom.Once it starts adj. high speed underway then low speed in gear at idle.You may have to adj. idle speed along the way.Not too high its tough on the shift dogs.<br /> Good luck.

 

[pittspilot]

Re: Please help a Rookie (slightly long)

Well, it helps to closely read the manual. I set the float too high as stated, becuase I measured from the high speed jet, and not from the casting. Ooops.<br /><br />Thanks for all the help, I was able to determine that my compression (while slightly low, is at least even) is fine, and that there is plenty of spark.