Ryobi Mower Is Difficult to Start, Spark Plug Replacement?

arst on 27/03/2022 - 18:56
Last edited 27/03/2022 - 19:07 by 1 other user

I have a Ryobi mower model is RLM4619SMB.
It is second hand I got it from a seller.

I found it is difficult to start recently, so I am trying to fix it with the easiest one, spark plug. I took it out and found it is dirty, bought a brass brush to clean it, used multimeter to test it, it shows 4.54 with 20k ohm setting, I don't know if indicates that the spark plug is still good? I put it back and tried ot start, no luck.

So my first question is, should I buy a new spark plug to try? Or don't wast the money?

And second question, assume the answer is yes, I would like to know if some cheaper spark plug can be used?

I am looking a replacement at Bunnings, which is $20. The model is BPR7HS,
https://www.bunnings.com.au/ryobi-spark-plug-to-suit-175-190…

I googled and found there are other places selling it with lower price, like
https://www.arizonaoutboards.com.au/outboard-parts/unsorted/…
https://autobarn.com.au/ab/Autobarn-Category/Shop-our-Full-R…

They are like 1/3 or 1/4 of price at Bunnings. I am wondering are they the same? Why Bunnings's price is much higher?

Also found another one but the model has 10 at the end, which seems to be the electrode gap? Is the same as BPR7HS??
https://autobarn.com.au/ab/Autobarn-Category/Shop-our-Full-R…

Appreciate if you can help..!

Home & Garden Lawn Mower RYOBI

Comments

  • Ocker on 27/03/2022 - 19:12
    +1

    Wow - just go out and buy a new spark plug - it will not send you broke (?).
    If that doesn't cure the problem then you can eliminate that cheap fix and still have a new spark plug for your efforts.

  • apsilon on 27/03/2022 - 19:29
    +3

    Buy the NGK one, it's exactly the same. You can even see in the Bunnings pics it's an NGK just being sold as Ryobi. Bunnings are more expensive because they're getting all the people who think it's lawn mower specific.

    This is why I went electric. No mucking about with fuel, oil, plugs, filters, servicing, starting, noise, smell etc.

  • Transient on 27/03/2022 - 19:52
    +1

    Apparently the number after the dash refers to gap width. One mentions it. The other does not. They have 2 different SKUs so may be the gaps are different. Hard to tell from the autobarn website.
    https://www.math.uwaterloo.ca/~rblander/NGK.txt

    Perhaps check the online manual for your model mower and see what spark plug they recommend?

    • arst on 27/03/2022 - 20:09
      +1

      I actually checked the manual, the recommend model is actually BPR6HS: https://manualsau.ttigroupna.com/system/files/214/original/r….

      However, the one selling on Bunnings is BPR7HS, and it says can be used for RLM4619SME. So I think both BPR6HS and BPR7HS can work. BPR7HS seems to have colder tempature based on what I searched on the internet.

      • apsilon on 27/03/2022 - 20:15
        +1

        Yes, the 6 and 7 is just the heat rating for the plug. If the manual says 6 I'd try and match it.

  • Muzeeb on 27/03/2022 - 19:54
    +1

    Have you cleaned the air filter?

    Does it need priming prior to starting?

    • arst on 27/03/2022 - 19:59

      I just bought a new air filter today. Will try tomorrow. But does it affect the start of the ower?

      • Muzeeb on 27/03/2022 - 20:01
        +1

        Yep. Big time if it's blocked and it will run like shit if you get it running.

        Combustion engines need fuel + air + spark

    • arst on 27/03/2022 - 20:06

      It needs priming.

      • Muzeeb on 27/03/2022 - 20:12
        +1

        How many presses of the priming bulb?

        Don't over do it = flooding

        • arst on 27/03/2022 - 20:28

          It says three time, do it slowly. I usually find it does not work and end up pressing more time…..omg..

          • Muzeeb on 27/03/2022 - 20:32

            @arst: Can you feel the bulb getting slightly harder to pump with each press?

            • arst on 27/03/2022 - 20:39

              @Muzeeb: Not sure. I will try tomorror. but if it doesn't, dose it mean the primer bulb needs to be replaced? Actually I have a feeling it might be the problem that the fuel does not go through..

              • Muzeeb on 27/03/2022 - 20:57

                @arst: Also

                Is there a fuel tap?

                Are you starting with the throttle wide open?

                • arst on 27/03/2022 - 20:58
                  +1

                  @Muzeeb: Yes, I open it every time.

      • BeamMeUp on 28/03/2022 - 17:43
        +2

        My old Briggs and Stratton 4 stroke says prime 3 times, I find I need to do it 10-12 times right from new . You can feel the pressure in the primer. Give it a good hard pull and she starts first time.

  • BeamMeUp on 27/03/2022 - 20:02
    +1

    Here’s some ideas. clean the plug, connect it to the spark plug lead, hold the threaded part firmly against the engine on the thread at the cylinder head, pull the starter and see if it sparks. If no spark the problem can be the plug or plug lead, check the connector inside the lead cup, if it’s loose give it a squeeze with some pliers. Plug leads can also fail. They burn out of break where the cable connects ithe spark plug cap, or a break in the cable or where it connects to the engine.
    If you have spark them pull the air filter off and try some WD40 sprayed into the carby, or pour a little bit of fuel into it if you are comfortable doing that, see if it starts. If it kicks but doesn’t continue to run it may be a fuel issue. Blockage, bad petrol?

  • arst on 27/03/2022 - 20:32

    Is the first part like what you said in the video? https://youtu.be/IiovKykg2pw?t=195

    • c64 on 27/03/2022 - 21:18
      +1

      yes, that is one way to test the spark plug. just make sure whatever you are holding is insulated otherwise you might get an zapped

  • askme69 on 27/03/2022 - 21:27
    +1

    Start Ya Bastard in the air intake.

    The plug in my old Victa looks like a used Sparkler and it still works.

    • BewareOfThe Dog on 28/03/2022 - 09:29

      I was about to suggest that, or a light spray of Alcohol/Methanol.

  • arst on 03/04/2022 - 18:38

    So, I changed the air filter today. Tried that method BeamMeUp mentioned to test if can see park. There is no spark. I bought a new spark plugs today and tried again, still does not spark. I am pretty sure I grounded it properly.
    https://photos.app.goo.gl/BgTD979W9c8K2vtB9
    So next thing I think is the lead or ignition coil…
    I might just take it to the shop for reparing…

  • c64 on 04/04/2022 - 00:04

    is there a brake or a ignition kill switch somewhere, maybe associated with throttle lever? that might be killing the ignition

    • arst on 04/04/2022 - 20:44

      That might be it. I will try the throttle level tomorrow and see.

      • Euphemistic on 05/04/2022 - 08:58

        Check out some google and YouTube on fixing a petrol mower. There’s plenty of good guides out there.

        Then come back to us with how you fixed it.

        • arst on 06/04/2022 - 21:07

          So I sent it to a shop to fix and I paid $85. The guy said that the oil is old settled at the bottom because I didn't use it often. He said he cleaned something (carburettor? not sure), and changed oil. Also told me I have to press the primer bulb 10 times because the fuel pipe is a little bit clogging.
          In this case I should have seen spark guess I just didn't do it right.

          • c64 on 07/04/2022 - 11:40
            +1

            @arst: oh well, at least you gained some experience from the trying to repair it yourself first

            aliexpress sell cheap spark plug testers than make it easier, such as https://www.aliexpress.com/item/1005004013740860.html . you put it inline and it is literally a bulb that flashes when the spark occurs.

            • arst on 08/04/2022 - 11:01

              @c64: Nice! Will get one defintely.

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