Echo SRM 230 running rich

[PTP]

There is a lot of black carbon deposits around the exhaust and the plug keeps fouling. Once the plug gets fouled, it will cut off. I can restart it, run it at full RPM's but it will foul again and cut off.

There doesn't seem to be a mixture adjustment screw on the carb. How do I adjust the mix?

[echoman8]

There is a lot of black carbon deposits around the exhaust and the plug keeps fouling. Once the plug gets fouled, it will cut off. I can restart it, run it at full RPM's but it will foul again and cut off.

There doesn't seem to be a mixture adjustment screw on the carb. How do I adjust the mix?

Hi,

Have you removed the spark arrester screen or cleaned it? After one of these carbonizes once, I have not had success in keeping them clean afterward.

Other than a restricted exhaust, I can think of nothing except the metering needle lever in the carb. If the carb has been worked on then it could be adjusted wrong. When pushing the tab of the lever (opposite the needle), the needle should begin to rise at one half the movement of the tab. If it begins to move the needle before it travels 1/2, then the motor will receive too much fuel.

Another possibility. If the carb has been repaired then the diaphragm on the metering side could be installed wrong. The correct assembly would be to place the gasket on the carb body, the diaphragm outside the gasket, and then the metal cover (plate). The improper assembly would essentially cause the same condition as a improperly adjustied lever.

Good luck,
echoman

Another obvious thing is a stopped up air filter. I assumed you had already checked for this.

[PTP]

The problem started a couple of days ago. The air filter was pretty dirty so I cleaned it up and the problem is recurring. I ran it again with a new spark plug and the air filter off and am getting carbon deposits on the plug in a minute or two.

The spark arrestor screen was removed months ago.

It runs very well until it gets fouled and then the trouble starts.

[echoman8]

Gosh, I am still thinking restricted exhaust.

Without an adjustment to high speed, the preset jet cannot get bigger and assuming that the carb has not been repaired lately, it would be a rare event for something to cause the needle to allow more fuel through.

Almost all conditions that occur cause a lean condition rather than a rich condition.

I would go back and check my fuel mix (touch and feel, smell). If you are working alone, little can happen, but with help or working with others anything could occur. It has been more than once that I have found diesel in a customers tank.

Now I have had erratic problems with the purge (primer) pump below the bulb. A quick way to disable it and test is to cut a piece of plastic (like from a freezer bag) and place between the bulb and the carb. Poke a couple of holes in the plastic for the 2 bolts.

It is a good possibility. I have all of my old echos rigged this way. The pump only loads the carb with fuel. It does not prime it. If you run out of gas, you may have to pull it a few more times with the choke on.

Maybe Phil G or MowerMedic will jump in here on this with advise.

Good luck,

echoman

[ed2hess]

So why not rebuild the carb.....or have you done that already? I guess when you cleaned out the exhaust port you checked to see if the rings looked okay?