2-strokes flood alot, tech guys: what causes this?

[causalitist]

a few of my older 2strokes, a wacker and a blower (echo pb420) tend to flood alot. the wacker was because it was sitting on the rack carb up while driving.. the blower just started flooding a few times a day, its a year old,plug and air filt are good.

every few lawns we have to pull the plug out and pull it over to rid excess gas from cylinder, no choke, full throttle, and it smokes to life.. classic flood.

im wondering, is there something in these carbs that gets wore out or out of wack that causes this? we drive around with the blower stored upright by the way. the blower is clean and runs great with high peak rpms. so you tech guys: what lets excess fuel into engine when its off??

i know you guys have had this happen, and it is costly when employees are sitting there 4 times a day trying to start it!

any tips/adjustments or things you guys replace to avoid this would save me a ton of time money.
thanks!

[jkason]

Carb is set wrong.

[causalitist]

ok ..

what on carb? high and low speed adjustments? dont seem like it since it runs nice.

the "lever" that the float pushes up and down?? i've never had bowl apart since buying it .... and started fine until now.

could there be debri in the main needle valve... the one that lets gas into bowl??? seems like that could be.. if it couldnt close all the way bowl would keep filling .. and i guess then into engine .. is this something that happens? would be nice to hear i just have to shoot some cleaner in that valve.

[jkason]

First of all, there is no bowl. It's a diaphragm carb.

If the cylinder is filling up, it is probably a venting problem. Clean your vent tube or replace the breather/vent thingie (like on an Echo).

If that fails, it is likely to be a needle/spring problem. This can be fixed with a $15.00 rebuild kit.

[BigFish]

It's not a tank venting problem, the vents only let air in, it won't let air out if its working right, so the tank will pressurize on a hot day etc. The carb inlet needle and seat are designed to take the pressure without leaking, and causing flooding.
Soo, like jkason said, get ya couple of rebuild kits, not the cheaper diaphragm kits and rebuild em. What I usually do is ****** the outside of the carb with spray cleaner before you take it off ! to get rid of the crud, then blow it off gently. Be carefull with the high pressue air when cleaning up the insides. Best to go to Zama's website, they got real good info on rebuildin.
After you've discovered that it still wont act right, be sure and get a new carb mount gasket 'cause they don't come with the new carb ya shoulda bought in the first place !

[echoman8]

Hi,

I kinda glanced at the replies so I may be repeating someone.

Sounds to me like the muffler screen is stopped up. If you are not working for the federal goverment (screen required), then I would take them out and throw them away. If you are, get new ones at your Echo dealer. Cleaning the old ones have not worked for me. They clog faster once they stop up the first time.

Although it is unlikely an internal carb problem, about the only place that can cause flooding in the carb is the needle and lever on the metering side.

Good luck,
echoman

[causalitist]

ok, thanks guys. in my experience a clogged muffler screen and it will run like its very rich... wont reach peak rpms etc.. i take those off on everything new i buy.
this is flooding. runs great after all the fuel is taken outa the cylinder.

so you guys are basically saying that the spring that holds the needle down(plugging the hole) is worn out. why dont i just bend the lever that pushes on diaphram/needle.. should be able to do it so it pushes on spring more, but hits the needle and diaphram the same.

i took it off, cleaned it very well, put it back on ... (with a fuel filter for my walkbehind no less hahaha) ... day1: flooded once day2: worked well

we will see.

[echoman8]

I am going to post some prior stuff that may apply to your flooding problem:

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PURGE PUMP
I have had problems with the "so called" primer bulb on echos and other small 2 cycle engines. It can give both alternating lean and rich symptoms.

The bulb does not prime the carb, it just loads it with fuel if it is empty. To do this, it has 2 rubber valves (duckbill valves). With age they quit working.

I remove the bulb, cut a piece of plastic (freezer bag), place between the bulb and carburetor housing, then put the bulb (and metal plate) on.

This disables the primer(actually purge pump) and you will have to depend on the choke to start (cold start only) just like it was in 1990 and before.

The duckbill valves allow air to enter the carb irratically (when bad).

**************************************************************

METERING LEVER AND CHEAP TRICKS


My "expertise" is quite old now. I had a shop for 10 years from 83 to 92. I sold Echo and other brands of saws and mowers. Our repairs of all units per month was 600 (mowers, motors, trimmers, chainsaws .....). For the past 12 years I have been doing tree work and using about 15 different echo units. (The blowers and extension saws have the same 21cc/24cc engine as the line trimmers) I have not seen many of the newer models. The quality of the seals and bearings may have changed.

About the external carb adjustment needle. This would be the low speed adjustment while the high speed would be preset with a fixed jet. If the high speed jet is partially clogged, you will probably have to find a shop that can clean it.

It was my impression that you wanted to repair it cheap, so the prior posts and this have some tricks I have used in and out of the shop. I live is a small west Texas town without a convenient source of small engine parts. So many repairs have to be done with the old part or used parts.

About bending the metering lever tab. Our old chainsaw mechanic taught me that. It really helps on starting. You will find that many new levers travel 3/4 of the distance before they open the needle. And if the old lever has to be used, it will be worn and bent ever so slightly causing the same condition. There are few carbs I work on that I do not bend this lever. I only observe the metering needle when doing this.


I hope this helps and shows you my perspective. I certainly did not mean to leave the impression that I am the "WORD" on echo. Some of these are just alternative repairs that I have done many many times and they have worked for me.

I believe most all of it can be used on 90 percent of the 2 cycle saws, trimmers, etc. regardless of the brand.

************************************************************************

In your situation, you would want to bend the lever downward to allow less fuel, but still have it lift the needle at about half of the travel of the tab.

Good luck,
echoman