Primer Bulb Really Work?

Discussion in 'Lawn Mowing' started by HighGrass, Aug 19, 2005.

  1. HighGrass

    HighGrass LawnSite Bronze Member
    from Z5 MA
    Posts: 1,237

    I have an Echo SRM 230 straight shaft trimmer that I really like....except for starting. It seems like no matter if If use the primer bulb or not, it still takes about 8 pulls to get it started for the first run of the day. If it's hot out, the rest of the day it will start on the first pull....usually.

    Do primer bulbs really make that big of a difference?
     
  2. Forest

    Forest LawnSite Member
    Posts: 108

    Primer bulbs do work if the carb isn't set too rich. It sounds to me like your jets need to be adjusted and or a whole carb cleaning. Does it smoke at all on start up, general usage. If so, what color smoke? All the primer bulb does, incase you were unsure, is squirts a little fuel in the throat of the carb.
     
  3. HighGrass

    HighGrass LawnSite Bronze Member
    from Z5 MA
    Posts: 1,237

    Actually, it doesn't smoke at all at start up. The funny thing is, I have three Echo units (Blower and 2 trimmers) and none of them start as hard as the SRM. The unit has behaved this way since new. But lord knows how long it was hanging around in the store. (Home Depot) It sounds like it might be time for a little carb cleaning.
     
  4. Forest

    Forest LawnSite Member
    Posts: 108

    It definently sounds like it's out of adjustment. Have you taken a look at the color of the plug recently. Is it Dark and wet looking, white looking or a tannish color? Sorry for all the questions to you question. Just trying to help. It definently sounds out of wack though. That's the reason I ask about plug condition. They tell a story.
     
  5. HighGrass

    HighGrass LawnSite Bronze Member
    from Z5 MA
    Posts: 1,237

    Don't worry about asking too many questions...keep asking.

    I pulled the plug out last week and it looked sort of tan. Not wet or oily at all. So, I checked the gap it and was right where it was supposed to be according to the book. Just to be on the safe side, I changed it anyway and it still started the same.
     
  6. jbell113

    jbell113 LawnSite Senior Member
    Posts: 654

    Hey forest , if you have time explain those 3 plug conditions to me
    ..
     
  7. Forest

    Forest LawnSite Member
    Posts: 108



    For grins before you rip it apart or take it in, I'd personally try adjusting the air mixture screw in a 1/2 a turn or so. If you have the owners manual it might specify the carb setting. If it does reset them all to factory settings. The more you thread the fuel/air mixture screw in the richer it becomes and vice versa the farther out the leaner it becomes. If the plug is looking a really light tan then i suggest giving it a bit more fuel. Don't be afraid to play around with it. As long as you remember the original settings then you'll be in good shape.
     
  8. Forest

    Forest LawnSite Member
    Posts: 108


    Jbell... There are three main shades of colors that can be read off of plugs that tell a lot about how an engine is running. If an engine is running rich the plug will show a really dark brown, almost black, color and is usually wet or smells richly of gas. The ground electrode won't usually display these symptoms as much as the center electrode will(the small piece of porceline with the metal center electrode protruding out). If it's running rich too you may see a little bit of wettness on the last thread or two. If it's running good(neither too rich or lean) the plug will show a light brown to tan color and may smell just a touch gaseous. This color or condition is usually a good middle ground to be in for plug color, assuming the engine starts properly, idles properly and revs through the powerband without hesitation. And lastly,
    you know you got a lean engine when the plug looks extremely light tan to white in color. This condition is a non-desirable condition because if lean enough you Can burn a hole in the piston as well as do other damages to the eninge. The reason for this is because a lean engine is a very hot burning engine.

    As a auto technition by trade, analyzing plug conditions is crutial for determining what's going on with a engine runability issue. I hope the info above helps you guys out. If you have any more questions just ask!-Forest
     
  9. Richard Martin

    Richard Martin LawnSite Fanatic
    Posts: 14,700

    A couple of things.

    The primer bulb on most modern small 2 stroke engine does not squirt a little gas in the throat of the carb. All it does is fill up the fuel lines and fuel pump with gas. You can pump the primer all day long and never get a drop of gas in the engine. When you close the choke all of the vacuum that is provided by pulling the starter actually pulls fuel out of the carb.

    Most carbs today have no means of adjusting a fuel air mixture. The only mixture screw I've seen in the last 5 years is on the Stihl BR400/420 series of blowers and it is capped off. The air fuel misture is set via the jet. If you want to fatten the mixture up you must remove the jet and drill it out. If you want to lean the mixture out you must remove the jet, plug the opening and redrill it to a smaller size.

    On carbs that do have a air fuel mixture screw turning the screw in leans the mixture and turning it out fattens the mixture. If you remove it you will see that the end tapers to a point. The pointed end can be moved into a jet in the carb. As the tapered point is screwed further into the jet it decreases the amount of fuel that can pass through the jet leaning the air fuel mixture out and visa-versa for when you turn the screw out.

    If your trimmer has always been hard to start then there could be a problem with how you are trying to start it. If it got harder to start as it got older then there could be a problem with the carb or the compression.
     
  10. HighGrass

    HighGrass LawnSite Bronze Member
    from Z5 MA
    Posts: 1,237



    If your trimmer has always been hard to start then there could be a problem with how you are trying to start it.

    Okay, here's how I start it. I prime it by pressing the primer bulb 3 times. I set the choke, place start switch on and start pulling. About 5- pulls later it starts to pop and usually by the 8th pull, it will stay running. I let it warm up a bit and slide the choke halfway open and I can usually start using it without it stalling.

    I also noticed that there is no mixture screw. The manual eludes to this as a emmisions issue. GO figure.

    I use the same gas as in all my other echo pieces.
     

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