Ryobi 31CC weed trimmer wont start

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  #1  
Old 05-30-07, 06:37 PM
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Unhappy Ryobi 31CC weed trimmer wont start

PLEASE HELP! I borrowed a weed trimmer from a neighbor and the fuel lines cracked and broke and i had to replace them. In the difficult task and numerous tries with different configurations i am stuck. I got the fuel lines right finally. Unfortunately now it wont start. I can spray carb cleaner into the intake and it runs until the cleaner is burned up. I am scared I may have messed up the valves inside the carb or something from the numerous primer bulb connections i had to try. I think i tried every possible fuel line configuration before I got it right. Any Ideas???
 

Last edited by jamesdonnae; 05-30-07 at 06:39 PM. Reason: left some stuff out
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  #2  
Old 05-30-07, 08:11 PM
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since the fuel lines broke only when you borrowed the trimmer I must assume that they was already brittle.And if that be the case,the damage (if any) to the inside of the carburetor has already been done.

Are you sure though, that you got the lines in the right places?There are 3.The bottom fitting on the carb.is where the line out of the fuel tank goes.Then a line runs from the top fitting on the carb to the largest nipple on the primmer bulb.The other line runs from the other nipple of the primmer to the other hole in the fuel tank.This is only the return line.Make sure too that the fuel filter inside the tank is on the fuel line.does the primmer button fill with fuel and hold it??If not reverse the two lines on the primmer only.If the trimmer still wont prime,or run,the carb.will have to come off.Be soaked in carb.cleaner and a repair kit put in.
 
  #3  
Old 06-12-07, 07:03 PM
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Unhappy i need help too

i also have a ryobi gas trimmer problem. mine is new (less than 6 months), but it will not run. at first, i thought i had the gas/oil mix ratio wrong, so i altered that. nothing. i cleaned the spark plug, the carbureator. nothing. i disassembled the carb and thoroughly cleaned it, i bought new gas and oil mix. nothing. it will start strong, while the switch is in 'start', but once i squeeze the throttle, it's like it bogs down or something. sort of like the engine doesn't have enough power to spin the shaft. so i tried pumping the throttle, to try to rev it up, start it spinning slowly. it doesn't matter, it still just dies after a while. the little flapper thing in the gas cap is not clogged. the fuel filter is not clogged. i can't take the stupid thing back to the store, because i'm a dummy and didn't keep the receipt. i've heard about some hi/low screws or something. can someone please explain that to me, or offer some other advice. i'm in need of help. thank you.
 
  #4  
Old 06-12-07, 08:41 PM
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sounds to me Jimmy that the muffler or the exhoust ports might need cleaning out.There clogged with carbon.Take spark plug out.clean port holes with piece of wood to keep from scrstching the inside of the cylinder or the piston and blow it out with air.Put plug back in and crank.
 
  #5  
Old 06-13-07, 08:08 PM
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Question thanks

thanks for the advice. i tried that, and it was not clogged, so no luck with that. BUT, i figured out that if i barely squeeze the throttle, it runs like a champ, but wide open. as soon as i squeeze it more it bogs down. maybe it's getting too much gas, flooding it out? the quarter-disc thing on the carb where the throttle cable connects, that moves the disc inside the carb, i moved the cable to a different hole so that it wouldn't open the valve so much, and it runs alright. the shaft spins and i used it for a little bit. still not much power though. is there some adjustment i can make to something to have better control, so it's not just shut or wide open?
 

Last edited by jimmyclubfoot; 06-13-07 at 08:11 PM. Reason: grammar
  #6  
Old 06-13-07, 10:48 PM
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turn the high speed adjustment screw out (CCW) 1/16 to 1/8 turn and see if the problem clears up.The adjusment screw is prob.going to have a piece of plastic over it ( a lemiter). This can be pulled off with a good needle-nose.
 
  #7  
Old 06-19-07, 02:56 PM
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Ryobi won't start

I too have a Ryobi gas TrimmerPlus 15", 31cc that won't keep running. Mine is very old, I bought it 11 yrs. ago from Home 'Despot' with the blower attachment (long type no longer in production). I use it lightly but all year around. I've never had to do anything to it except change a worn out bumper knob. I've always been very careful mixing the oil and have never touched any adjustments. It has started faithfully and exactly the same for over a decade until the last time I used it. It wouldn't keep running. I ignored it a month and now it won't start at all.

Can you elaborate on some low tech routine maintenance or cleaning rather than screwing with the carb jets? I'm thinking my problem is spark or maybe fuel flow related. I pulled the plug and it looks good but dry after many tugs on the rope. I never got any indication of a spark on any choke setting, which is very unusual. It always started and ran a few seconds on full or half choke until today. I don't suppose there is a magneto that needs replacing is there?

I'd take it to a local shop but I know they will mess with and smash the carb jets and it will never run right again. That's exactly what happened to my next door neighbor's identical unit. After the repair shop his never ran right and he had to junk it and buy a new one including all new attachments. I don't want to go down that road.
 
  #8  
Old 06-19-07, 07:19 PM
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Smile

Take the muffler off and try to start it without,the muffler,it will very loud,do not let it run very long,you might have a clogged muffler,if so I soak it in carb,cleaner over night and rinse it out with water then I heat it with a propane torch and get it wery hot and then pick it up with some pliers and hit it on the concrete to get any carbon out of the muffler flakes will come out when you hit it on the concrete,be careful not to get burn in doing this,hope this helps.

Jerry
 
  #9  
Old 06-20-07, 07:58 AM
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If the muffler try does not work, then you have a carb problem and not getting enough fuel at the high speed jet. This could be due to the adjustments are not open (backed out) far enough or that the diaphram and fuel pump portions of the carb have hardened up and need replacing. Kits are available but the numbers are in various locations on the carb.
 
  #10  
Old 06-22-07, 07:45 AM
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Ryobi gas trimmer won't start

I removed and checked the muffler. I don't think it is blocked or causing the problem. I stuck a wooden stick in through the plug opening and moved it around. There was carbon present but the ports were clear. I checked the plug and gap. It is fine. I squirted carb cleaner into the cylinder, reattached the plug and muffler and gave the rope a pull. It sputtered, so there is spark.

That leaves fuel flow as the problem. I removed the dark, brittle fuel line from the bottom of the fuel tank and fuel dripped slowly from the tank. Unfortunately, each time I tried to reconnect the hose, it cracked. I need to replace all the fuel lines and in doing so hope to find the air leak or blockage that could be my main problem. I still find it hard to believe that it would run exactly the same for eleven years then suddenly change air mixture out of limits unless it was from an air leak in the fuel line eliminating suction or a blockage in the line or carb as suggested. I'm sure the carb needs a rebuild of any parts that deteriorate over time but it did start and run well until quite recently.

First, I'm hoping I can find more of this tiny clear plastic fuel line somewhere and then replace all the lines. One short fuel line from the carb appears to end at a bracket with an open hole. Is that an overflow or is something broken off?
 
  #11  
Old 06-25-07, 05:44 AM
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Ryobi gas trimmer won't start

Replacing the fuel lines didn't clear the apparent blockage. Is there any kind of filter in the carburetor I could clean or replace?
 
  #12  
Old 06-25-07, 09:01 AM
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Yeah, FLPCGuy,there is a filter in the carbretor,its on the fuel pump side (the side with just 1 screw).But more than likely the diaphragms in it is hardened and not working as they should and you'll have put a G&D kit in it.
 
  #13  
Old 06-26-07, 02:06 PM
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Ryobi carburetor

Thanks Repair_Guy. I'll try to find a 'G&D kit'. I took apart the 2 screw side already and didn't see any dirt or blockage. Any tricks I should know about the rebuilding this carb, special tools, etc.?
 
  #14  
Old 06-26-07, 05:29 PM
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Aaaaah you have a Zama carb. with the primmer pulb.momnted right on the fuel pump.Just take the red duck valve that is just under the primmer bulb out B 4 U put the carb.and end plates into your carburetor cleaning solution.Be careful and run something through this valve to see if it clear of any debre,and will open.And get any bits of old gesket that might stick on the carb off.Otherwise it will suck air from these places.If the primmer is very dark in color,replace that too now,Because you will have to B 4 long anyway.Reply back with type and number on carb (which will be prob.a C1U ******or C1Q******)?? ETC. and someone can look it up and tell you the right primmer bulb to use.

You don't have to worry so much about the metering lever.these come pre set and are right on the money 98% of the time.
 
  #15  
Old 07-08-07, 02:24 PM
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Won't keep running

I have a Ryobi 767rj with a 31cc engine. I believe it is about 6 years old. It suddenly bogged down when I reave it up. I thought the spark plug had gone bad and replaced it. The engine cranked and run normal, but this week I was weed eating and about 30 minutes into my trimming the engine bogged down again. I found the engine would start if I put it on full choke. I moved the choke control to center position and it would run for a few seconds and die. I can't get it to run on non choke position. I check the gas lines and primer and the carbruetor is getting fuel. The spark plug is wet.

Do you have any suggestions.

Thanks in advance.
 
  #16  
Old 07-08-07, 07:14 PM
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Sounds to me Sam Smiley,like your trimmer is getting too much air and not enough gas.Take the plastic limiter cap off of the high speed adjustment screw on the carb (the nearest one to the air filter) unscrew it 1/16 - 1/8 turn.Then try it.
 
  #17  
Old 07-10-07, 07:31 AM
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Smile Ryobi 31cc engine

Reply Guy,

I removed the plastic cap covering the adjustments. One being black and the other white. the white was located toward the front of the engine and the other toward the air cleaner. I tried ajusting but to avail. I found the black one had to be set total counter clockwise(on the stop) for the engine to start. I finally shook the trimmer real hard and the engine started and ran normal. I think that is telling me there is some trash in the carb. Could this be the trouble and if I need a repair kit for the carb where do I get it?

In my repairing I found out to check the starter rope knot before getting to carried away. (I check my chainsaw and tied a new knot in it) The thing broke and the rope went inside. I was able to rethread the rope and put on the handle, but I have about 2 inches of slack. Please tell me how to remove the clutch, install a new starter rope and adjust the rewind.

Thanks so much.
 
  #18  
Old 07-10-07, 07:35 AM
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Smile Ryobi

Sorry I meant Repair Guy.
 
  #19  
Old 04-25-10, 07:15 AM
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Ryobi 31cc SN 4031 UB24RA; EM 18"

ZAMA Carb

No primer bulb on this Model

Neighbor gave it to me 2 years ago. Ran well, but fuel leaked at the 2 fuel line nipples at bottom of tank.

Removed muffler. No carbon build up.

I just fixed that leak. Hard to start. Erratic performance. Will start after choke and then starts at 1/2 choke position. Bogs when throttle opens. Removed plates from both sides of carb. 2 screws on each side. Fuel pump diaphram is not dried up, flexible. mixed fuel system cleaner w/fuel. Gas is presently dripping out of carb venturi.

Thinking of removing carb, removing the 2 plates and diphram and soaking body in solvent.

There are 2 adjustment needles on top w/delimiter caps, yellow and red. Red is nearest the engine. Athird needle is close to throttle shaft. What do these control?
 

Last edited by borgward; 04-25-10 at 07:22 AM. Reason: Added info
  #20  
Old 04-25-10, 11:41 AM
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Originally Posted by borgward View Post
Thinking of removing carb, removing the 2 plates and diphram and soaking body in solvent.


I cleaned my first couple of 2 cycle diaphragm carbs a couple of weeks ago. As I understand it, soaking the plastic parts in carb cleaner is not recommended, and I used spray carb cleaner instead, which reduced the amount of dis assembly I need to do.

Worked like a champ when I got done. That was probably carb cleaning for cowards.

I have a Tecumseh 4 cycle engine that hasn't worked quite right despite being the carb being cleaned several time with spray carb cleaner. I'm thinking of taking that one apart and dunking it to see if that solves the problem.
 
  #21  
Old 04-25-10, 01:53 PM
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Plastic

Which plastic parts are yo referring to?

I planed on removing the to side plates and the rubber diaphragm, as I did not want to expose it to the solvent. Are there more plastic parts in the body?
 
  #22  
Old 04-25-10, 03:22 PM
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Similar problem with Ryobi trimmer (4 cycle)

Ive been reading this post and many others on a lot of sites about 4 cycle trimmers but havent found my answer. I have a Ryobi 975r 4 cycle trimmer. Will start on choke but will not run on idle or 1/2 choke.

I checked the muffler for excess carbon. Recently adjusted valves and plug is good. Replaced fuel filter and lines (easier to feed lines thru tank if you cut end to a point and tie a string to it).

I replaced the primer bulb (not mounted on carb), and pull rope (broke after too many pulls lol). Rebuilt and cleaned the carb (Zama C1Q). Zama web page pics dont show 2 plastic diaphram plates like I have hope I didnt get them reversed (any guidance?).

Engine runs on full choke only. Limiter caps are off the carb, and it seems like the inboard screw (mixture) has very limited impact on engine performance on full choke-heck that may be correct for all I know(neadles dont look damaged). On full choke the engine is pretty unresponsive to throttle input (but Im guessing thats the nature of full choke).
Spent too many hours on this dog. Ready to launch it down the driveway but I hate to give up on anything. I couldnt check compression (dont have the right adapter for my guage) but it ran strong just recently (prior to giving up the ghost).
Any suggestions beside trash it?
Thanks
Dave
 
  #23  
Old 04-25-10, 04:17 PM
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When you have the choke on and run it for about ten minutes see if the plug turns sooty or does it stay clean?

If it turns sooty you could have an ignition problem or low compression.

If it stays clean, the choke is either subbing for the primary and idle circuits or crutching the fuel pump diaphragm. I would lean more toward this scenario than the ignition/compression. This would explain why the adjusting screw had no effect on the running. The choke circuit is a separate little animal.

Yep - full choke = not much out of the throttle.
 
  #24  
Old 04-25-10, 04:26 PM
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Plugs not sooty, just a little black, no carbon running off on my fingers. One thing I didnt mention is I didnt tear off the Welsh plug. The Zama instructions scared me from trying that.

Could I have reversed the 2 diaphram plates (old were clear plastic, new ones are one tinted and other clear with various cutouts)?
 

Last edited by dokmand; 04-25-10 at 04:42 PM.
  #25  
Old 04-27-10, 05:04 PM
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ryobi run on choke only

Beside what I mentioned before, I checked compression and its 105 psi. Added a squirt of oil and its still 105. Not sure of the accepted value for compression.
 
  #26  
Old 04-27-10, 09:28 PM
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The 105 is workable. A small chance the problem is in the ignition, but most likely in the fuel system.
 
  #27  
Old 05-02-10, 04:20 PM
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Ryobi 4 cycle runs on choke

Went thru the carb again (Zama C1Q-P8) soaked it for 3 days in old syle carb soak cleaned it out and same problem runs only on full choke. Even used another new carb kit. Took the exhaust off and cleaned it again. No change. The mixture scrw is more responsive but still wont run without full choke. Funny thing for a min or two it ran without choke and without the exhaust but after literally 1 min it stopped. Im beaten. Could it be the check valve under the Welch plug?
 
  #28  
Old 05-16-10, 12:37 PM
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Ryobi starts, wont run at full throttle.

Could these problems be due to the magneto?

I have two Ryobi ss30 weed eaters that exhibit the same problem as described above: starts under choke, will idle, but when given throttle, they die. They have less than 10 hours run time each.

Can replacement magneto's be bought?
 
  #29  
Old 05-16-10, 01:53 PM
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They would be ignition modules and it would be very unlikely the engines would start at all if they were causing a mid to full throttle range cop out.

The most likely would be in the fuel system. If you have the mixture screw set too light or too heavy you can get the same problem. As a rule, though the carb isn't providing the fuel in the mid to upper throttle range. That can be a plugged circuit or a faulty fuel pump diaphragm, or a plugged fuel filter, a collapsed fuel line, a perforated fuel line, or a plugged vent in the fuel cap.

I wouldn't invest in modules just yet.
 
  #30  
Old 06-05-10, 03:31 PM
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After reading countless threads on numerous forums about Ryobi grass trimmers I devised a solution: None of us should buy their crap anymore.

These foreign made, low quality, pieces of junk are perpetual lemons designed to make their makers and places like Home Depot wealthy. Ryobi is always $20-70 cheaper than everyone else's machines, but none of them last. The vast majority run for 3-6 months, then die. Its been this way for 5 yrs or so.
 
  #31  
Old 06-05-10, 08:34 PM
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Bought mine in Aug of 97'.... still goin strong

Beer 4U2
 
  #32  
Old 09-15-10, 11:44 AM
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Thumbs up Fuel mixture adjustment fixed mine SS30

Mine eventually only ran in half choke then only full choke cold, then no more full throttle and would stall out.
SS30 from aprox 2005, **** republik of CALIFORNIA!!! (emmisions)
Zama carb, see thier web site for tuning
I let it sit too long, didnt use fuel stabilizer.
Read up, did the following, and runs like new:
Thanks to everyone for posts
the final key was the mixture
replaced fuel lines with good ones, old ones dried and cracked, clogged. Still looking for replacement sceen filter.
blew out carb with cleaner. let sit over night, still wouldnt run right
removed the friggin red and white mixture limiter caps with pliers
burned and mailed ashes to C.A.R.B. and EPA. LOL
turned two screw 1/4 turn counter clockwise. (richer)
Left low rpm mix, right high rpm mix
USA Zama : Service Tips
Runs like new again!! rotated lower half 90 degrees for edging, motor runs better in upright position. less likely to leak fuel too.
Driveway edge looks awesome now!!! Beer 4U2
 

Last edited by Delphin; 09-15-10 at 02:43 PM.
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