'72 202HD 20HP Fuel Problem

I need a little help troubleshooting this problem...

Once I get the boat on plane for about 1 minute the RPMs keep going down as if I'd let off the throttle. I have found that if I spray a little premix into the carb as this is happening it revs back up. The bulb remains firm and I have checked my hoses for holes and poor clamping meaning I don't think I'm losing my prime. Once I get some fuel to it, it's not difficult to start. Squeezing the bulb doesn't seem to be as effective at keeping it running as spraying a little premix into the carb. I did remove the fuel pump. I'm not sure what I'm looking for but the gasket, the part with the little reed valves in it (not to be confused with THE reeds) and the diaphram all look to be in great shape. I have not touched the carb yet.

I personally think there's something wrong in the carb. I'm thinking about just ordering a fuel pump and carb kit and be done with it. What say you?

Thanks in advance!

Re: '72 202HD 20HP Fuel Problem

Yep, sounds like you have some gunk in the carb. My Evinrude kicker just did the exact same thing. I took the float bowl off the carb and it had a bunch of crap in it. Cleaned it out with some carb clean and now it's running like new. Even starts with one pull.

Re: '72 202HD 20HP Fuel Problem

Most of those carbs have a steel needle in a brass guide closing a rubber seat so I will address my comments to them. Remove the carb and take off the bowl. Now push out the pin and remove the float. Be careful. One end of the pin is knurles. the pin only comes out one way. If you invert the carb, the needle should fall out. If not use a fine needle nose pliers to extract it. Unscrew the guide. At the bottom of it will be the rubber plug with a hole in it and a brass or copper washer. The plug will stay in the guide but the washer may stay in the carb casting. The rubber plug has two different sides so pay attention as to which way it is in the guide before you remove it

The reason for this explanation is that since squeezing the fuel bulb does not noticeably correct the problem but squirting fuel directly into the carb does, I believe you may have a piece of junk partially clogging the needle hole, or varnish may be causing the needle to hang up partially closed. Clean the needle, the seat, and the cavity below the seat and guide. you need not remove the fuel line fitting to clean this cavity. WD40 seems to work quite well at varnish and crud removal. Now: when you go to reassemble the carb, the correct setting for the float is: with the carb inverted, the float should be parallel to the casting where the bowl sits. A little lower is acceptable since in operating position the float will be a little high and the mixture will be a little rich. A little high is not acceptable since this will cause leaner running when the carb is in operating position.

The only different carbs are: some have a rubber tipped needle and some have a fine helper spring connecting the needle to the float. I do not think yours has either.

Re: '72 202HD 20HP Fuel Problem

Frank Acampora said:

Most of those carbs have a steel needle in a brass guide closing a rubber seat so I will address my comments to them. Remove the carb and take off the bowl. Now push out the pin and remove the float. Be careful. One end of the pin is knurles. the pin only comes out one way. If you invert the carb, the needle should fall out. If not use a fine needle nose pliers to extract it. Unscrew the guide. At the bottom of it will be the rubber plug with a hole in it and a brass or copper washer. The plug will stay in the guide but the washer may stay in the carb casting. The rubber plug has two different sides so pay attention as to which way it is in the guide before you remove it

The reason for this explanation is that since squeezing the fuel bulb does not noticeably correct the problem but squirting fuel directly into the carb does, I believe you may have a piece of junk partially clogging the needle hole, or varnish may be causing the needle to hang up partially closed. Clean the needle, the seat, and the cavity below the seat and guide. you need not remove the fuel line fitting to clean this cavity. WD40 seems to work quite well at varnish and crud removal. Now: when you go to reassemble the carb, the correct setting for the float is: with the carb inverted, the float should be parallel to the casting where the bowl sits. A little lower is acceptable since in operating position the float will be a little high and the mixture will be a little rich. A little high is not acceptable since this will cause leaner running when the carb is in operating position.

The only different carbs are: some have a rubber tipped needle and some have a fine helper spring connecting the needle to the float. I do not think yours has either.

Click to expand...

Thank you very much. I will check this out tomorrow after work.

Re: '72 202HD 20HP Fuel Problem

I had a little time during lunch to fiddle with it. I removed the carb and bowl. The float is held in by a pin with with screw head and threads on one end. I just unscrewed that, slid it out and the float came right out. Like you said, the needle fell out. I didn't go any farther yet because I ran out of time. I will finish up after work since I need to go by the parts house anyway. By the way, there is some trash in the float bowl that's stuck to the bottom. It might be floating around when there's fuel in there though.

The gasket for the float bowl was a gooey mess. I'm assuming it was from a tube. Should I purchase some Permatex (which kind?) type gasket stuff or should I order a kit which would include a "proper" gasket.

Thanks!

Re: '72 202HD 20HP Fuel Problem

Success!

The needle and seat were clean. Like I said there was some trash in the float bowl. I went ahead and bought some cork and cut some new gaskets not knowing if just Permatex #2 would suffice. I think that's what was used before and apparently that didn't work out too well.

As a side note, I'd been seeing some fuel in the "pan" surrounding the power head and never could figure out where it came from. Perhaps the new gaskets will solve that problem. We'll see.

I took it to the lake and did laps neat the ramp at WOT for about 30 mins. I notice that my (fairly new) inline filter is picking up a lot of trash. I think it might be time to get a new tank.

I really feel a lot better about this little engine. Every time I fix it I learn a little more about what can go wrong with it. And on this little engine there's not that much that can go wrong (that I can fix anyway).

Thanks again!