2 Stroke Engine Help

My gummie is kicking in so we’ll see if this makes sense.
I have a backpack leaf blower that was running fine a few years ago, but I switched to the premix in the jug vs mixing my own. I can’t get it to run at full rabbit. It just bogs until eternity. I’ve changed the fuel filter & breather, broken down the carb and resealed it, spark arrester is off and fixed the exhaust leak. I just can’t get the full bunny. It runs fine up until 3/4 throttle, then brrrrrrrrrr.
Thinking I should just replace the carb? It’s the non adjustable carb too.

 

I have a similar Echo as yours and have had the same problem in the past. Although it seems you checked everything, have you checked the condition of all the gas lines? Mine had a slight hole from deterioration that wouldn't really leak, but would suck in air at higher RPM's causing it to bog.

 

If you have one, check your prime/surge bulb for any cracks or pinholes.

 

If there are no air leaks then it's...
Not enough fuel
Or bad gas

Pour out the pre mix that's in there first. Mix your own with 93 octane gas and on the richer side of a ratio (50+:1)
Start it and hold half to 3/4 throttle open for 5 minutes then 3/4 to full bursts until it's cleared.
I had a chainsaw that developed a similar tic that it would only run well with a certain octane and mix ratio. Also the quality of the mix makes a difference too. Premium only!

 

Clean the sparkplug?

 

I have the Echo 760 blower and after 10 years finally needed the carb replaced. I run the regular pump gas with Amzoil 2stoke oil.

A note about canned gas: It too has a shelf life. I drained all the gas out of one of my generators and put a qt of canned gas it for storage and it would not start. Drained all the canned gas and out and went back to pump gas and it fired off. The canned gas was about a year old and never opened until that day.

 

New diaphragms in the carburetor??

 

I have had two echos - they’re notorious for cracks in the fuel lines. Both of mine had it and ran rough. Easy enough to replace and to clean / replace the carb if needed.

 

Yeah. I got the rebuild kit and did that last year thinking it would fix it. Surprisingly, all of the gaskets were in good condition

 

I would have never of thought that. It ran great when I first used it, but never since. I’ll give it a shot.

 

I believe with a little research you can find how to adjust the jets on the carb. When mine was new it started to run lean and the dealer said he adjusted the main jet to fix it. That worked until last year when my neighbor was using it will I was away for the winter and he changed the carb.

Don't continue to run it lean as this trash the engine from running hot and low on lube.

 

They made these with 2 different carbs. Mine is the non adjustable version. I did put the new jet in when I rebuilt it.

 

Ok so the exhaust port is clear, the screen is clear, and there is no obstruction for the muffler. Plugged screen will cause this, so if clear then, check all fuel lines for pin hole leaks, primer bulb leak, is the screen in the carb clear or replaced, in tank filter, looks like it has a fuel tank vent, disconnect that and see, looking at schematic without your serial number that carb may have no adjustment except for idle speed..

 

Right and it idles just fine. I ordered a new fuel line kit. Gonna try that and some fresh fuel.

 

Yes that would be my suggestion to start with

 

Sounds like the gas is the problem.

 

I strongly advise Y'all not to use pump gas (With Ethanol)... The ethanol is what eats up the fuel lines/primer bulbs/carbs... Find a gas station that sells ethanol free gas... Especially after a renew of all the lines and primer bulb and carb... Start with fresh Non Ethanol fuel... The best oil out there for the least amount of carbon build up is Yamaha Yamalube 2 stroke oil... As said.. Mix 50:1 ...

You'll thank me many years down the road...

 

Silly thing to check, but look at the air filter and clean accordingly. You'd be amazed at how much debris they catch on a backpack blower, and it'll show itself in higher RPM.

 

You say to brrrrrrrrs or does it bwaaaaa? Does it sound like a 4stroke or like some kids car without an airfilter?

Pull the plug. Whiteish gray or black?

 

This completely sounds like a mixing problem (idles fine, runs fine all the way up to 3/4 throttle, but bogs down at full throttle). It has to be the carb.

 

And hell.. they are cheap nowadays.... But like I said above... New everything up and then run ONLY ethanol free gas...

 

www.pure-gas.org

 

I’ve ran it without and same.

 

It sounds like a 4 stroke at full throttle. Did a plug change a year or 2 ago chasing it. I don't run it often, but when I do I don't let it bog. I just keep it a 1/2 throttle to blow stuff around.

 

I'm going to start with the least expensive option and work my way up to r&r the carb. I soaked the original when it was apart with cleaner and scrubbed it. All of the ports seemed to flow fine, but process of elimination at this point. I think I've seen my version of carb for like $100 on ereplacement. I don't necessarily want to just get a new blower. It has some sentiment to it.

 

I wish I had a station closer to me. Closest one is still an hour away; and an airport.

 

There is a low jet - idle screw and a high jet - throttle screw.
Separate adjustments.
If it idles ok, but bogs at full throttle try turning out counter clockwise the high jet screw.
If it gets worse go clockwise.

Now if it needs throttle to keep running the low jet idle screw needs adjusting.

 

This is the carb. From what I've found, it doesn't have any adjustment screws aside for where the throttle cables come in.
https://www.ereplacementparts.com/carburetorwyj257-p-519848.html

 

i know this isn't helpful here....but I'm so glad I ditched small engine yard equipment! I could never troubleshoot their issues. I'm never pulling a cord 10 times to not start a weedeater ever again!

 

I went with a battery snow blower for that reason. Now we don't get snow like we use to. If we did, I would have gone the 2 stage gas. But if my push mower and lawn tractor crap the bed, I wouldn't be apposed to a battery push mower for the size yard I have.