2003 Honda 20hp Sometimes Won't Throttle Up

[scrampbell]

Engine: 2003 Honda 20hp (BF20D3 SHA)
Symptoms: 50% of time, engine runs fine. Other 50% of time when I try to throttle up it will get to about 20-25% throttle and won't go any higher. When this happens, engine will eventually die when I throttle back down to idle. I can restart the engine right away with no problem. When it doesn't stop at 20-25%, I can run long distances at high throttle with no problems.
What I've tried: Changing Spark Plugs.
Other things to note: Gaskets on both sides of carburetor look worn; the carburetor gaskets look serviceable, but the muffler plate gasket looks bad. Do you think this could cause my problem or should I replace additional parts while I have the carb off?

The fact that sometimes it runs and sometimes it doesn't along with the symptoms makes me think that it's a seal somewhere that sometimes seals just right and other times doesn't quite make a good seal which gives me fuel delivery issues. What do you think? Thanks again!

 

[hondon]

Re: 2003 Honda 20hp Sometimes Won't Throttle Up

More likely you have a peice of crap moving around in the float bowl that will intermitantly restrict the main jet.Take that carb side lower cowl off and drain the carb into a translucent fuel safe small container and see what you see.Take a fuel sample direct from the fuel tank and see what you see there as well.Any water contamination and will almost certainly have carb work in your future.

 

[scrampbell]

Re: 2003 Honda 20hp Sometimes Won't Throttle Up

Thanks a ton for the response Hondon! I'm looking forward to following your suggestions tonight after work.

If I did have water in the gas tank... what kind of "Carb work" would I be looking at? More than just a cleaning? I already had the carb apart when I posted the first time (when I started, I was just going to replace all the gaskets).

If it's a piece of crap in the main jet, a good cleaning should do the trick, right? Of all the tiny holes in the main jet, some appear to be ever so slightly smaller than others. Is that normal or do I have some kind of buildup?

Thanks again!

 

[hondon]

Re: 2003 Honda 20hp Sometimes Won't Throttle Up

I do'nt know what kind of crap you saw in that float bowl when you first openend it up ,but this can be a difficult carb to completely clean without untrasound and even then,sometimes,EEH.No matter how you do it that carb has to come completely down and all parts cleaned entirely and inspected.ALL orings in that gasket kit WILL be used including the tiny one you are likely not sure where it goes.

 

[Mas]

Re: 2003 Honda 20hp Sometimes Won't Throttle Up

Are you still on the same tank of gas?

Try pumping the bulb on the fuel line when the motor is acting up. If rpms increase, sure sign of bad fuel pump.

What about the temp of the motor when its running crappy. I'm not sure if your motor has it, but my Evinrude has a rev limiter if its running hot.

Check for a good strong blue spark as well. You can buy a cheap tester that grounds to the motor for about 10$.

Any chance of testing cylinder compression?

 

[scrampbell]

Re: 2003 Honda 20hp Sometimes Won't Throttle Up

Update/Resolution:

There was a buildup of gunk on the tiny holes along the main jet that didn't get completely cleaned the first time through. Taking the carb out a 2nd time and cleaning out the gunk did the trick.

Thanks again for the help!