Ryobi RY253SS 2-cycle trimmer dies after about 10 seconds

[CWatters]

Ive managed to kill three Ryobi strimmers. They get harder and harder to start and then a compression test shows lack of compression. Sometimes you can see the piston is scored. Not sure why as I use fuel filters and the right amount of oil. Someone once suggested its important to let them warm up before use or you can get micro seizures?

Anyway I think normal is 90-110psi with a minimum of 70psi so yours is a bit low. Thing is once mine started they tended to keep running so not 100% convinced thats it. Check the anti spark mesh on the exhaust as others have suggested.

 

[RevB]

The next suspect would be the fuel filter located on the end of the fuel supply line down inside the tank, or possibly the supply line has a crack or pinhole in it. These flexible fuel lines don't last but so long. This unit has been around for quite some time.

F4040 Tygon yellow fuel line is rated for gasoline.....not all yellow, or for that matter, any color, lines are gasoline rated.

 

[RevB]

Unfortunately this barrel-valve carb (see Amazon page here for photos of what carb looks like) has no high/low adjustment. As per suggestion from an earlier post I did loosen exhaust, but no change.

Amazon.com

 

[Chuckers]

...replaced the carb with the one here, from Amazon. Runs fine now. This reinforces Auto Doc's earlier comment about ruiXing being "one season wonders".

But isn't that just another disposable "one season wonder" carb?

 

[RevB]

Amazon.com

Loosen is not removed....mud daubers love, for some reason, to build mud capsules in the muffler. Make sure that's not the case. Otherwise, remove carb, disassemble, inspect and blow all passages out with at least 30 psi or higher.

What you describe can be either fuel starvation or blockage. I use a small syringe filled with fuel to drip fuel into the carb throat to check if it will continue to run when supplied with fuel. If not the reason lies elsewhere.

 

[LMPPLUS]

Trying to repair a Ryobi RY253SS 2-cycle trimmer. Starts up fine, runs for ~10 seconds and dies. It dies regardless of whether full/no-choke, full/no-throttle. Restarts right away, but exhibits same behavior (which leads me to think not an electrical issue). Here is what I've done:

• New 50:1 fuel in tank
• Dry compression: 80 psi
• Wet compression after dripping some oil into cylinder: 120 psi (so some leakage around rings? would this explain symptoms?)
• Cleaned passages in carb, gaskets/diaphragms seem in reasonable shape
• Intake and exhaust gaskets look fine
• Applied 10 psi pressure to carburetor fuel intake pipe and it holds steady
• Applied vacuum to fuel inlet tube going to tank, and it sucks up fuel, so no obvious obstructions in tube or fuel-filter
• Cleaned some carbon buildup from exhaust port
• Pressure tested crankcase: holds steady at 10 psi
• Vacuum tested crankcase: holds steady at 15 in Hg, returns to 15 when I rotate engine

Only adjustment on carb is throttle idle screw. Might be possible to adjust the needle on the barrel-valve of the carb, but looks like a special tool may be needed.

Would appreciate any ideas of what to try next.

 

[rhkraft]

The crack or pin hole in the supply fuel line seems noteworthy. Fill the tank and see if it runs OK. If the problem only occurs after the fuel level drops it is probably a cracked fuel pickup line. Air is sucked into the crack and the engine falters.

 

[Pitt]

I have recently experienced the same set of circumstances w/my Ryobi RY251PH strimmer. (Manufactured 10-22-15)
I must have dropped mine as I had a small piece coming off the carburetor with what looked like a ball behind it.
Order the $9 Amazon Chinese flavor of the day and attached.
What I discovered is that it runs at a totally different "richness/choke" setting which we cannot adjust.
Pull a few times with choke on 100%.
Whether it starts or not, then move choke to somewhere around mid setting.
Start it here.
Mine runs BUT if I totally shut choke off so more air goes thru it does exactly like yours.
I think the "richness" setting is off in the ChiComm specials and we can only adjust mixture with the choke setting.
If this works for you, be sure choke is tight so it doesn't vibrate totally open and then die again.
Please advise.
For proof that mine has lasted 10 years as a residential user a photo of manufacturing date sticker is attached.

 

[mpqualdie]

Trying to repair a Ryobi RY253SS 2-cycle trimmer. Starts up fine, runs for ~10 seconds and dies. It dies regardless of whether full/no-choke, full/no-throttle. Restarts right away, but exhibits same behavior (which leads me to think not an electrical issue). Here is what I've done:

• New 50:1 fuel in tank
• Dry compression: 80 psi
• Wet compression after dripping some oil into cylinder: 120 psi (so some leakage around rings? would this explain symptoms?)
• Cleaned passages in carb, gaskets/diaphragms seem in reasonable shape
• Intake and exhaust gaskets look fine
• Applied 10 psi pressure to carburetor fuel intake pipe and it holds steady
• Applied vacuum to fuel inlet tube going to tank, and it sucks up fuel, so no obvious obstructions in tube or fuel-filter
• Cleaned some carbon buildup from exhaust port
• Pressure tested crankcase: holds steady at 10 psi
• Vacuum tested crankcase: holds steady at 15 in Hg, returns to 15 when I rotate engine

Only adjustment on carb is throttle idle screw. Might be possible to adjust the needle on the barrel-valve of the carb, but looks like a special tool may be needed.

Would appreciate any ideas of what to try next.

If you use gas with ethanol in it the carburetor diaphragms are probably shot. You should be using non-ethenol gas. Check that the fuel line and pickup weight in the tank are still intact. This is very common with weed eaters and chain saws. If tgat doesnt fix it, you can buy a new carburetor on ebay, usually for about 20 bucks. Change that and put new fuel lines in it and it should work well for you.

 

[Pitt]

Also just ran across this photo of carb replacement.
Mine had 2 holes, does yours?