1980 Mercury 9.8: No Power

I'm hoping someone out there can help me. I've got a Mercury 9.8 (110) that won't go any faster than a trolling motor in gear. A little background ... I've replaced the plugs, fuel pump, carb software, and impeller in the past month. I went out today and checked for spark and everything seems to be fine. After checking that, I pulled the plug wires to see if the problem was there. When I pull one of wires, the motor keeps on chugging (in neutral), but when I pull the other it dies instantly. Any ideas?

Re: 1980 Mercury 9.8: No Power

One other thing, I took it out a couple of weeks ago and it did rev up like it was supposed to for about 5 minutes, but then back to the snail's pace.

Re: 1980 Mercury 9.8: No Power

Ok, I pulled the plug that kept running and it's as clean as when I pulled it out of the box. I'm assuming that this means that no fuel is getting to it. I really need some help here, please.

Re: 1980 Mercury 9.8: No Power

I your 9.8 is the same as my 7.5 it only has one carb to feed both cylinders. Therefore, it would seem to me that the cylinder that is firing clean is the one that is getting fuel since you stated it would run on after pulling the other plug wire. It cannot run without fuel.

Did you pull the other plug to see what it looked like? If it was wet then it is not firing. You had to have the carb off to replace all the gaskets. Did you reset everything to where it was before removing the carb? Also, did you check to make sure the float was set correctly? It may be that you did not get the spark advance back in correctly or the carb may not be adjusted correctly. When you get it running next time shoot a little fuel mixture in the carb throat and see if it speeds up. If so, then you have a carb problem. Good luck.


Steve

Re: 1980 Mercury 9.8: No Power

Thanks, Steve. I pulled the plug and it was dry as a bone, which makes me think that something is clogged between the carb and the cylinder, but I'm not sure how to unclog it if it is.

Re: 1980 Mercury 9.8: No Power

You might want to do a compression check now.

Re: 1980 Mercury 9.8: No Power

chattfisher said:

Thanks, Steve. I pulled the plug and it was dry as a bone, which makes me think that something is clogged between the carb and the cylinder, but I'm not sure how to unclog it if it is.

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Is it possible that you lost part of the carb gasket into the intake area for the cylinders? Someone else may have a good idea on how to check to see if anything is blocking the port going into the cylinder. I have never had the engine on one of these that far apart.

Steve

Re: 1980 Mercury 9.8: No Power

Thanks, Steve. I pulled some schematics for my motor, so I'll check. I'm going to get a compression gauge and check compression after that.