What's wrong with my Ryobi trimmers???

[kebo]

I have two Ryobi 2 cycle string trimmers, one is an older model 790r, the other is a newer one but not sure what model. They both crank easily enough, and idle ok but as soon as you give them any throttle at all, they want to die. I mean just like you hit the kill switch. What's up with them?? It sounds like a air/fuel mixture issue to me.

One the older 790r, the foam air filter was soaked with oil/gas mixture so I tried cranking it with the filter off and it runs a bit better, but still wants to die when you barely crack the throttle.

Have not tried adjusting any of the mixture screws. Any ideas?? Thanks!

 

[Patches]

Sounds to me as though the spark arresting screen in the mufflers are plugged with carbon. Remove the muffler from the engine and you'll find a metalic screen, sometimes attached with screws, in the port of the muffler. Remove the screen and clean the carbon from said screen, making sure you can easily see through the screen. This should cure your problem

 

[kebo]

Thanks, will pull the muffler off of one of them take a look at it to see if it's all clogged up.

Keith

 

[Coyote machine]

If you're using gas that is older than 90 days get it out of the machine and go with fresh mixture. Ethanol based gas is absolutely NO good after 90 days of sitting. And check the spark arresters too as already mentioned. Don't screw with the mixture screws until you have done both of the above on any machine that takes gas!
Change your plugs too if they've been exposed to the ethanol gas that sat beyond its shelf date.

 

[kebo]

I pulled the muffler off of the 790r trimmer and there was no spark arrestor screen that I could see. If it has one, it is inside the muffler. Will try the new plug and fresh fuel next. Thanks!!

 

[2manyrocks]

Got the same issue with an Echo SRM 2200 trimmer. It was running fine until I ran it out of gas, and then put in some premix that had been sitting from last year. It starts, but then dies as soon as I give it throttle. I was thinking the fuel pump diaphragm in the carb was bad, but do you think it's the old gas?

It died like 2 strokes used to die when the points and condensors were shot, but this unit has electronic ignition.

 

[Patches]

I pulled the muffler off of the 790r trimmer and there was no spark arrestor screen that I could see. If it has one, it is inside the muffler. Will try the new plug and fresh fuel next. Thanks!!

Really! I haven't seen a 2 stroke lawn/garden implement, chain saw, etc. without a spark arresting feature in the last 30 or more years, unless it has been removed; I believe they're federally mandated. Some are located inside the muffler, if the muffler is a two piece unit(pull apart) and some are externally mounted(at the exhaust aperture), retained by a plate and a couple screws. I have seen them so thoroughly plugged as to look like a piece of metal. You should look more closely as I honestly believe it has some sort of arrester :thumbsup:

 

[Patches]

Googled Ryobi and clicked on SERVICE PARTS, which brought up two windows: click on "Buy MTD Online" and enter model # 790r. Part #'s
753-04312 arrester screen
" 04313 arrester plate
" 04314 arrester hood
" 04315 arrester screw

So your Ryobi #790r string trimmer does have a spark arresting screen: all you have to do is find it

 

[kebo]

Ok, I worked on the 790r some this evening. Dumped the old fuel and put FRESH fuel in it, with 2cycle Lucas Oil mixed to about 42:1. I will catch some flack for this I know, but the 790r is 32:1 and the other Ryobi trimmer I have is a 50:1 mix so I decided to split the difference. I do not want to have to keep up with two different 2cycle fuel cans. That would just be too much hasssle and I'm willing to deal with the consequences, if there are any. I also added a little bit of SeaFoam in the gas can. That stuff is costly!! About $10 for a 16 oz container.

On to the second part.... After putting in the fresh fuel, I changed out the old plug and put in a brand new one. Now, it cranks up really easy, but won't even idle now. It used to be that after cranking it several times to get it to warm up, it would idle good. Now, after it's warmed up some, it will idle for about 5-10 seconds and then just die on it's own. Giving it any throttle only quickens the shutdown.

As stated before, there is no spark arrestor screen on it that you can see, unless someone has removed it previously. This is possible since I bought it used. Or, could it be integral with the muffler on this particular one?? Don't know, but I do know that when I pulled the muffler off, the exahust port was clear, and the mating part of the muffler was clear.

I guess next I need to check the fuel filter to make sure it's not stopped up and check the fuel lines.
Thanks again for your help.

 

[windy acers]

I have run my ryobi half chocked for about 2 years now.I use prem gas with stp gas treatment. hold it by the string end an slam it against a tree.SAVE THE SPOOL. DON'T ASK HOW I KNOW :confused2::laughing: