Help with carburetor rebuild kit

Hey guys I have a 1978 mercury 800 SN:4836723 that i believe has a fuel issue. When I start it up on muffs at home there is not a single problem with the engine. It starts right up and keeps on trucking no problem. When I'm on the water however I have some issues. When I put the engine into gear it almost always dies. Its quite a routine to get the warm up throttle down and put it into gear with enough gas to get it moving before it dies. Also at WOT every once in a while it will start bogging down and die. Then its about 20mins of me cranking on it to get it restarted again.

I was going to start by rebuilding the carburetors and possible putting on a canister fuel filter. I have been looking all morning for the carburetor rebuild kits and so far i think I need this one 812953. So, is this the correct rebuild kit? Do I need to buy a float separate from it? I ask about the float because I have been looking at this kit on a bunch of sites and some of the pictures have the float, and some of them don't.

Also, what do you think about a separate fuel filter? I have read in some posts that they are wonderful and in others that they suck and you will have problems with them.

Re: Help with carburetor rebuild kit

So after posting this and thinking about it for a minute I decided to try and run the motor in a bucket of water instead of muffs because I have heard of something about back pressure or something when the prop is fully submersed in water. After filling up a 40g bucket and putting the motor in it, it acted exactly the same way it does when im in the lake. Hard to start unless I have the warm up throttle pushed most of the way up to start.

I decided to take apart a carb because I have never seen one before and take a look at it. Nothing looked warn out to me, in fact it looked like it had been recently serviced. The float was not sticking and everything looked clean. So I put it all back together and decided to see what the screws that control the richness do. After reading the manual and messing with them for a while I think I found that they were set way too rich. I followed the instructions in the manual on how to adjust the richness and was able to get the motor started up without using the warm up throttle and it sounded a lot smother while idling. I put it into gear just to see what would happen and it didn't stutter or anything it went right into gear. Any chance that this was the whole issue with it being hard to start and dying with WOT? Still think i should get a fuel filter with a water separator.

Re: Help with carburetor rebuild kit

Absolutely....the mixture settings make all the difference when trying to accelerate. Normally people set them to achieve a good idle, and then they are two lean to allow acceleration. A water seperator is a good idea.

Re: Help with carburetor rebuild kit

Exhaust back pressure from being in the water changes the scavenging enough that you need to make those adjustments with the foot in the water and even better, put the prop under load.