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Hello,

I have an ES-250 that has run great for many years. Last few years have only used Trufuel and I use it year round so it never sits long with old gas.

Went to start it last week and it was giving me a real hard time. Definitely primed, Choke or no choke (it was 95° out), air filter completely off or on like normal, throttle open or closed…wouldn’t start for about 50 pulls. That has never happened before.

Finally puttered and stayed alive, and seemed to run functionally well. However, I noticed a burning smell that really almost smelled like burning plastic, but could have been an oil smell. I then noticed puffs of smoke coming from inside where the engine and muffler are.

I shut it down and it wafted smoke for five minutes or so and then stopped.

I figured after 8 years or so, might need a freshening up. So today I put on:
- new carb
- new prime bulb
- new lines including new fuel filter and bleeder
- new air fil
- new spark plug

Added some fresh TruFuel and was ready for a brand new machine. Except again it wouldn’t start. Finally after 20 or so pulls, it puttered to a start and then ran.

Ran and used it for about 5 minutes and have a few observations, but maybe I’m being skewed by it still not starting well. I swear it is down on power/air flow and also sounds grittier (but to be fair I am almost always using it with earbuds or earplugs in).

Finally, I also smelled some of the burning smell, but not as bad. When I shut it off, there were 3 or 4 wafts of white smoke and then it stopped doing that. Smoke could possible have been from residual leakage that still had to burn off?

I’m just worried that the carb wasn’t the issue and that the compression is shot in the motor somehow and oil/fuel is leaking through to the exhaust? Trying to figure out I’m better off chucking this whole thing in the garbage and sucking up the $250 for a new one vs continuing to use this if it’s not worth it, or even dangerous.

Attaching a video of it running after the refresh. Maybe someone with trained ears can tell something. Also, I realize this isn’t a Bentley motor, but is it odd that, even after it’s warmed up, sometimes 100% throttle runs a less rpm than 95%, or so?

Thanks!

Remove the muffler and check the exhaust port
Good chance it will be carboned up .

bertsmobile1 said:

Remove the muffler and check the exhaust port
Good chance it will be carboned up .

Click to expand...

thanks!

It makes sense since it’s running so hot. There is a little guard piece angling there gasses out of the muffler. Is that what needs to come off? That area and those bolts are sort of blued in color from the heat, and with just a screwdriver T27, I can’t break them loose.

Or, do I need to remove the next bigger piece (the muffler itself?)?

thanks!

Ok. Pulled the exhaust muffler screen and it looks fine to me?

The brand new spark plug is AWFUL with wet black after only 5 minutes of life. Mega rich??

thoughts?

Interestingly, here’s my old spark plug that came out with the rebuild I did today. WAY less black wet soot than this brand new one, above.

i wonder if this new carb is junk and jetted wrong?

Ezatnova said:

Interestingly, here’s my old spark plug that came out with the rebuild I did today. WAY less black wet soot than this brand new one, above.

i wonder if this new carb is junk and jetted wrong?

View attachment 61705

Click to expand...

Did you buy it from a mower shop or do an Evaby/Amazon lucky dip
I don't know how many good ones are sold through them but I do get a lot of stuff with brand new carbs on them that are obvious quality control rejects , fished out of the scap bin and sold as OEM for xyz

We MIGHT have had a red herring here!

after looking at the exhaust port that was quite clean, I was thinking about the mega black wet spark plug and it running so rich.

Unless I’m missing it, I don’t see how the jets on this carb are adjustable. So next thought…making sure I attached the right hoses to the right ports from fuel tank to carb.

While I did verify the hoses were going to the correct places, I also noticed something else. The vent hose and the return hose were super long compared to the OEM setup, where they only extended 1/2” down from the grommet. These were inches down and INTO THE FUEL.

So I took pulled those lines way up, snipped the excess and reattached to the one way vent and return port.

The cylinder was flooded with fuel and carb cleaner so it needed two pulls to start, and the was spitting out of the muffler outlet port slots, but then it settled in and really seems smooth now! I didn’t want to lay into it and test power sound after full throttle since it’s 9:30pm and people might not be thrilled.

Anyone think those two hoses that were extended down into the fuel could have been my problem running so poorly and rich after the full refresh?

bertsmobile1 said:

Did you buy it from a mower shop or do an Evaby/Amazon lucky dip
I don't know how many good ones are sold through them but I do get a lot of stuff with brand new carbs on them that are obvious quality control rejects , fished out of the scap bin and sold as OEM for xyz

Click to expand...

it was the Amazon $26 special

Should not make any difference as the carb should have check valves in it
A blocked tank breathing system can overpressurise the fuel tank so that the metering needle unseats which floods the engine
THis is the "pop off pressure" that every idiot on face book / U-tube who thinks they know about engines is obsessed with and professions who do know never bother with
The carb should hold ≈ 7 to 10 PSI inlet pressure for a good 10 to 15 minutes
If the metering needle it too low then the carb will flood easily
At the factory every one is tested
Pass => goes to Echo
Fails => goes to a rebuilder for correction & resale
Want to know how many bad meetering diaphragms I find on brand new ebay / amazon carbs ?

bertsmobile1 said:

Should not make any difference as the carb should have check valves in it
A blocked tank breathing system can overpressurise the fuel tank so that the metering needle unseats which floods the engine
THis is the "pop off pressure" that every idiot on face book / U-tube who thinks they know about engines is obsessed with and professions who do know never bother with
The carb should hold ≈ 7 to 10 PSI inlet pressure for a good 10 to 15 minutes
If the metering needle it too low then the carb will flood easily
At the factory every one is tested
Pass => goes to Echo
Fails => goes to a rebuilder for correction & resale
Want to know how many bad meetering diaphragms I find on brand new ebay / amazon carbs ?

Click to expand...

Sorry Bert but you got three things wrong here.

First the tank vent only prevents the fuel tank developing a vacuum. Actually the tank needs some pressure so the carburetor fuel pump works more efficiently.

Second setting the metering lever too low will not cause flooding but instead cause a lean burn condition. It is setting it too high that will cause either an over rich condition or flooding.

Here is a troubleshooting chart for the Zama RB carburetors.

bertsmobile1 said:

Should not make any difference as the carb should have check valves in it
A blocked tank breathing system can overpressurise the fuel tank so that the metering needle unseats which floods the engine
THis is the "pop off pressure" that every idiot on face book / U-tube who thinks they know about engines is obsessed with and professions who do know never bother with
The carb should hold ≈ 7 to 10 PSI inlet pressure for a good 10 to 15 minutes
If the metering needle it too low then the carb will flood easily
At the factory every one is tested
Pass => goes to Echo
Fails => goes to a rebuilder for correction & resale
Want to know how many bad meetering diaphragms I find on brand new ebay / amazon carbs ?

Click to expand...

Thanks Bert and Startech!

Before messing with it today I pulled the plug to check it out. Wet and black again after the 3-5 minutes of lightly running it last night. Wiped it off and reinstalled.

Gave it a cold start (one thing I read about that I’ve NEVER done is holding the throttle open all the way while starting), and it fired right up on the second pull. First was choke on and it sputtered. Second was choke off and it fired up.

Once warmed, it still ran fine but I could tell it wasn’t putting out full power at throttle, and was sluggish to ramp up.

Youtubed a bit on where the low and high carb adjustments were on this thing (oddly/thankfully I didn’t have those little plastic caps down blocking the screws), so I went about adjusting those.

Adjusting the high SIGNIFICANTLY improved things and it is running like the good old days at full throttle. I also tweaked the low but that wasn’t off nearly as much.

My hope is that the high was so off on the rich side, and that this will cure my wet black plug issue. Will pull it shortly once it’s cool. I ran it for about 10 min to hopefully burn off any richness on the plug from the initial startup and carb adjusting.

It also ramps up in throttle super quick now. Seems like at least 30% more top end power than I was getting before the adjustments. Noticeably kicks back in the hand, from the air forcing out the tube.

Will report back at least once about how the plug looks and if I’m all good. If it is still rich, I guess I’ll go down the road of tearing open the carb. I just would be shocked if it is, with how strong it’s running now.

Pulled the plug and it was significantly drier and more of a blue burn on the tip, and not all black and wet. Hopefully that’s that!