Fuel Blow Back

[jteneyck]

I know I saw a posting here a few months ago where the saw was blowing fuel back from the carb and wetting the air filter.  I have a similar problem with a leaf blower.  It ran fine for many years and then wouldn't start.  I took off the carb., cleaned it and replaced all the gaskets, diaphrams, and needle this Summer, and it ran fine again, until I needed it to blow leaves yesterday.  I had to pour fuel directly into the carb. inlet to get it to start.  It ran sort of OK for a few minutes then stalled and would start only by pouring more fuel down the carb., and then would run only until that fuel was burned.  I replaced all the fuel lines, confirmed the fuel filter is OK and pulled the muffler to confirm it's not plugged and the piston is not scored.  I got it to run but it won't rev., and sprays fuel back out the carb.  I took apart the carb. and sprayed it with cleaner and blew it out, but reinstalled the same gaskets and diaphrams because I didn't have any new ones.  They looked OK, but ???  Anyway, no improvement.  Another observation is that the Lo speed jet adjustment doesn't seem to do anything no matter where I set it, as long as it's open somewhat.  What do you all think?  Thanks.

John, who needs to clean up a bunch of leaves.

[Rocky_J]

Check to see if there is a spark arrestor screen in the muffler. If there is, then remove it and even waller out the exhaust outlet a little bit with a prydriver. Then slap it back together and fire it up. I have gotten two perfectly running blowers out of neighbor's garbage cans and fixed them this way.

[jteneyck]

Hi Rocky.  No spark arrestor and no obstructions.   I was hoping that would be it, but no luck.  What else?  Thanks. 

John 

[kenskip1]

My guess is worn rings.The compression is forcing the mix past the rings and onto the air filter, Ken

[jteneyck]

Worn rings?  Hmm, time to get out the compression tester and see what it shows.  Thanks for the lead. 

John

[kenskip1]

Sir, you had to poor fuel directly into the carburetor to get it started is a classic sigh of worn rings.The engine does not have enough compression to draw the mix in.When the blower warms up (thermal expansion) you loose what little compression that you have.Ken

[Al_Smith]

Oh I have basically the same problem on a Ryobi blower .I suspect perhaps it's a blown crankcase seal but I haven't investigated yet .For that matter if it is I have no idea where in the world to find parts for it anyway but I'll cross that bridge when the time comes .

As it is I recently acquired a Stihl back pack blower that I do believe will blow the bark off a tree so the Ryobi is just another project of many that is on the back burner .

Here's a little tip, if you completely blow a seal, which happens , you will not get enough impulse to the carb to pump the fuel . A blower is one of those tools that sits for 11 months out of a year and those seals do go hard like a rock after a period of time .Much in part to the EPA's blessing of ethanol laced gasoline .

Seldom will you wear out a set of rings on a blower .

[Cut4fun]

On stuff I seen spitting gas back out of carb. They usually had excessive wear on the intake side of skirt. Just something to check if your going to re-ring one, take a closer look at the skirt.

[jteneyck]

Thanks for all the ideas,  guys.  I checked the compression this AM and got 140 psi.  I was pretty impressed since this blower is at least 15 years old and a cheap Ryobi.  Actually, the thing is built pretty well and ran all those years with no troubles until I had to rebuild the carb. last Spring. 

Al, you came closest to the root of the problem.  I suspected it was an air leak somewhere in the crankcase, since I had replaced all the fuel lines, cleaned the carb, checked the compression and verified the muffler wasn't plugged.  What else could it be?  Back when I was rebuilding the carb. I took off the plastic intake manifold between the carb. and the crankcase because I had never seen a reed valve pulser system.  When I did that I broke the gasket (my curiosity often gets me in trouble) so I made a new one from some sheet gasket material I had.  Well, there was a crack in that gasket when I took it off this AM.  I didn't have any more gasket material lying around so I glued the crack together with some superglue and put some Form-a-gasket on both sides when I reinstalled it.  It started right up and seems to run just fine now.  I don't know how long that gasket will hold; hopefully, long enough to get my leaves cleaned up. 

[Cut4fun]

I took off the plastic intake manifold between the carb. and the crankcase because I had never seen a reed valve pulser system.  When I did that I broke the gasket (my curiosity often gets me in trouble)

teeter_totter  didnt know we were dealing with reeds or  I would have suggested  something different too.  Good deal on finding the fix  smiley_clapping

[jteneyck]

Sorry, I'll try to be more specific of the particulars next time. 

I ran the blower for over two hours with only one carb adjustment needed.  It doesn't start quite as easily as before, so there might still be some underlying problem, but it idles and runs just fine once started.  Best of all, I got my leaves cleaned up and didn't spend any money in the process. 

But if I were in the market for a new blower, what brands should I look at for non-pro use, say for a max. usage of about 10 hours per year?

[Rocky_J]

The little Echos have always been dependable, although I think the newest ones have catalytic mufflers which will clog up very easily and will make the blower unusable after a few tanks of fuel unless you modify them. But for only a couple dollars more the cheapest Stihl hand held blower is about twice as strong. I think I paid $149 for my BG55 about a year ago and it's twice as strong as my buddy's little Echo blower.

[Al_Smith]

Actualy before it was mentioned I had forgotten that the Ryobi does have a reed .

Good that you found the problem .More often than not it's something simple that simpley gets over looked .Traveled that road a time or two myself . ;)

On that subject though and not to skew the thread ,I once had a Stihl chainsaw that gave me fits and it turned out to be a tiny little tear in an intake boot that I wouldn't have thought in a million years could have been the problem .You just never know some times --until you know .