Ryobi RY253SS 2-cycle trimmer dies after about 10 seconds

ttimtucker

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  • / Ryobi RY253SS 2-cycle trimmer dies after about 10 seconds
You need to be able to adjust the carburetor. If it will start and idle for about 10 seconds, it could be as simple as a carburetor adjustment. Increase idle screw temporarily and try to adjust high and low screws. Sometimes you can take an electrical crimp connector with hard plastic cover and heat it up and hold it on the screw until it cools to form the threads.
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.
 

Auto Doc's

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  • / Ryobi RY253SS 2-cycle trimmer dies after about 10 seconds
I was mistaken earlier, these had the ruiXing throw away carburetors that were nonadjustable. We called them "one season wonders".
 

cliffeby

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  • / Ryobi RY253SS 2-cycle trimmer dies after about 10 seconds
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.
I always use starting fluid without an air filter to keep it running when I don’t know if it’s air, spark or fuel. My experience says it’s your fuel filter.
 

RevB

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  • / Ryobi RY253SS 2-cycle trimmer dies after about 10 seconds
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.
Got mud daubers? Check the exhaust can. A possibility....not the possibility.
 

ttimtucker

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  • / Ryobi RY253SS 2-cycle trimmer dies after about 10 seconds
I replaced the fuel filter and fuel line, and it behave a little better, but still died. I then 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".
 

Auto Doc's

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  • / Ryobi RY253SS 2-cycle trimmer dies after about 10 seconds
At the end of use on a regular basis, it will help to empty the fuel and then try to start it a couple of times to draw out anything left in the carburetor. I started doing that and it greatly reduced my Springtime weed eater problems a few years ago.

Buy new fuel mix or mix your own every Spring. Non-Ethanol works best if you have it available.

I have several older Ryobi and Stihl weed eaters that have been reliable over 15 years with just regular upkeep like fuel lines, air cleaners and spark plugs.
 

tonycarfagna

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Try relacing spark arrestor screen or clean old one in muffler these are notorious
 

darksoul251

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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.
I just go on ebay and replace the carburetor. Something goes wrong with them. They cheap on ebay. Make sure to get the right one.
 
Joined
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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.
Hi. As a specialist in small engine repair, everyone will be saying to check this and that. The first thing that you have to do with all 2 strokes is remove the exhaust and look at the piston. If you see bar codes (I call them) known as score marks, you are wasting your time, the engine is finished. If no score marks, make a hook out of a piece of wire and pull the fuel filter out of the tank, remove it from the line and you should be able to blow through it. Some filters have a water absorbing filter and it should be changed. If you can blow through it, then the problem is in the carb. There is a 10micron screen and it could be blocked with water, dirt or a micro film of old fuel across the screen.
As it runs, it’s not a spark issue at this point, unless the flywheel key has sheered.
Compression testers don’t work on 2 strokes, as you can have compression, but if you have score marks, the pressure collapses in the crankcase and the fuel sits on the bottom. The fuel and oil mix are no longer in an atomised state.
The thing that everyone has to understand is that from the fuel cap to the spark plug is that it’s a pressure vessel. A carb only controls the fuel going into the engine by movement of the piston.
Vacuum and pressure tests only confirm that there is no air leaks.
If all of your fuel related issues are confirmed not to be the problem, I would look at the flywheel next. A fella with a stihl some time ago had the same issue as you. He put a new carb on, fuel lines and filter and still the same thing. He contacted me and I told him “well I know it’s not a fuel issue and there were no score marks “😂 I told him to look at the flywheel and the key sheered and the flywheel rotated just enough for it to start, but quickly died. He put on a new flywheel and never looked back.
 

Mike88se

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Seems like a lot of time & trouble for a Ryobi but kudos for persistence. I would have advised customer to buy a new (and better) machine but if customer really wanted the Ryobi fixed and was willing to pay then I would have just bought a new carb straight away and skipped all the diagnostics. Glad it worked out for you.
 
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