# Spark plug for Ryobi 990r brushcutter



## mplehning (Jun 26, 2006)

Hi,

I have a Ryobi 990r that my father handed down to me and it's been pretty wonderful (except for the part where I wind up covered head to toe in pieces of grass and whatever else it throws at me) until a week ago when I was trimming. It would quit running when I got into thicker grass (although nothing worse than it's been through before)....and then would give me a hard time starting back up again.

So yesterday I cleaned the air filter. I took the gear housing on the trimmer head apart to put some new grease in since there wasn't a fill cap like the manual indicated.....put new grease in, put it back together. 

Now I can't get it started. After lots and lots of pulling and then letting it sit to get unflooded, it'll start for a few seconds. Seems like long enough to get up enough torque to turn the trimmer head, then it dies. 

My main question is, I wanted to replace the spark plug because I'm sure it's the original one. The manual says to replace it with Champion RDZ19H. No one around me seems to carry that. Today I looked at an Advance Auto, and a Champion book that was pretty new said to use RDJ7Y/DJ7Y for the 990r. But in looking for application charts and such on the web, I only come up with RDZ19H as the plug I need.

Does anyone know of a replacement (Champion or otherwise) for RDZ19H that will go in the 990r? 

Also, if those symptoms don't sound like the plug, I'm open to suggestions! 

Thank for your help.


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## tom tilson (May 1, 2006)

If it starts and then torques up when you give it the throttle,I belive somehow the head gears are jammed. I am sure that these units have centrifugal clutches which would allow it to idle, but possibly kill it when the clutch engages. Try this. Loosen the shaft clamp near the end of the engine and slide off the trimmer head and shaft as a unit. Now see if it runs and will rev. I really believe something is not right in the gearbox.


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## mplehning (Jun 26, 2006)

Thanks Tom,

The behavior I experienced on Sunday was that once it finally tried to start and then began to spin the trimmer head, the engine stalled. This took all of about 10 seconds, by the way. I did try, once, starting it with the trimmer detached but I wasn't sure if that was a good thing to do or not for the drive cable. Something sounded kinda not right when it started without the trimmer attached. I thought about borrowing a blower attachment my neighbor has (since they seem to be fairly universal) and see if that makes a difference. You think it's ok to fire it up without anything attached?

Monday when I tried fiddling with it again, I couldn't even get the engine to turn over which made me think the plug isn't sparking.

I would not be surprised if I packed too much grease into the gear housing....I would imagine you can have too much grease. So I will also try taking that back apart and scooping some of the grease out.

I'm still frustrated about the whole spark plug finding fiasco..........

Thanks,
Matt


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## tom tilson (May 1, 2006)

It should not hurt anything to run the engine without the shaft and cable. What you probably heard was the clutch rattling. See if it will rev up. While the shaft is off, use pliers at the engine end of the shaft and see if you can twist it fairly easy and note if the head is turning. Over greasing should not jam the head. When you make the check without the shaft installed, you are isolating the problem to one or the other.


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## mplehning (Jun 26, 2006)

Good news (sorta)..........I'm pretty sure I figured out that my spark plug isn't the problem which means (for now) I don't have to scrounge around finding a replacement. I believe my problem is not getting any gas.

I tried your suggestion, took the shaft apart and was able to turn the cable with a pair of pliers which in turn spun the trimmer head without effort. Since I had the plug out already and cleaned it off, I tried primer bulb to see if any gas would come spurting out (I read that somewhere). Noticed that the primer bulb, after I pressed it, didn't pop back out but instead stayed kind of sucked in on itself. That was a new twist. 

Put the plug back in, primed it (again, sucked in on itself), took the plug out, it was dry. Put it back in, tried to start the engine, didn't even sputter. 

Then I remembered (and left it out of my original post) about having the cover off, and spraying some starter fluid in the carb to "kick start" it. That used to work on my old Chevy pickup and on my mower when it gets fussy. What happened was that it started up long enough to burn up the starter fluid and then quit. That's the behavior I had on Sunday...but I completely forgot the starter fluid part in my post.

So, I think maybe while I was cleaning stuff, I must have done something somewhere to the fuel line or something got in it. I've got fresh fuel in the tank and everything looks connected and "unkinked". 

Something somewhere must've come un-done........


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## blackwell_316 (Jun 27, 2006)

the spark plug you can get from sears.com.
sounds like your carb is dirty. you can take it apart and clean it. and see if that works


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## certifiedtech (Jun 30, 2006)

This post was deleted by "certifiedtech"


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