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#4425938 - 06/08/17 01:30 PM Makita 4 Cycle Trimmer - any mechanics on here?
Rab6715 Offline


Registered: 12/02/16
Posts: 72
Loc: Midwest
Hey small engine shade tree mechanics and professionals -
I have a 2.5 year old Makita trimmer with low hours - maybe 10. Its a 4 cycle, separate gas/oil, not a 4-mix. This year it developed a problem where it became hard to restart hot and if i got it going, it would idle out and die. When cold, it starts first pull, it idles well when cold and has amazing power. If i shut it off for 15-20 min, restarting is only made by holding down the throttle and pulling. If i get it going then, it will then idle out. Things I have done so far:

1. Adjusted idle screw - I have a tachometer
2. Adjusted/checked valve lash - they are perfect
3. Spark arrester was removed day one of ownership
4. Oil is clean
5. Air filters are clean
6. Carb body and related gaskets appear tight and clean
7. I metered resistance of coil its within spec. I have not done this when its hot, will this make a difference?
8. Thought it was venting problem, removing gas gap - no improvement
9. Took it to local mechanic, who said it was idle screw wiggling and getting out of adjustment, so I put some loctite on the screw to hold it down. I used low strength locktite, but it made no difference for hot restart problems.
10. NEw spark plug with correct gap made no difference.

I'm at a loss for what it could be. I'm close to buying a new carb, but they are like $50 and I really don't think its the carb. The carb is not adjustable since its a 4 cycle. Any other suggestions for me? I love this trimmer, but its giving me a headache with this problem. This is a professional model and cost about $300 new, so i'd like to fix it.

Any ideas? Thanks so much



Edited by Rab6715 (06/08/17 01:32 PM)

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#4425958 - 06/08/17 01:53 PM Re: Makita 4 Cycle Trimmer - any mechanics on here? [Re: Rab6715]
doitmyself Offline


Registered: 06/03/02
Posts: 6219
Loc: MI
Man, you've done some excellent diagnostic work there and have covered a lot of possibilities. Many years ago I did have a situation where the coil acted up only when warm. This article talks about it some: http://www.your-lawn-care-basics-coach.com/Lawn-Mower-wont-start-when-hot.html

It sure seems to be temperature related. Is a carb kit available...they tend to be very inexpensive. Fuel line and filter are good?

Hopefully someone else with more experience will chime in.

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#4425968 - 06/08/17 01:57 PM Re: Makita 4 Cycle Trimmer - any mechanics on here? [Re: Rab6715]
Kamele0N Offline


Registered: 02/09/15
Posts: 2041
Loc: Slovenia
Check if there is any air leak between carburetor and cylinder...spray wd40 in between when it will be running...if engine will quit...then it is gasket...
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#4425971 - 06/08/17 02:03 PM Re: Makita 4 Cycle Trimmer - any mechanics on here? [Re: Rab6715]
MichiganMadMan Offline


Registered: 07/18/11
Posts: 250
Loc: SE Michigan
Any chance it is running on winter fuel?

Years ago I came home on a unusually warm spring day to find all my gas cans looking like weeble-wobbles in my garage from all the butane trying to return to the atmosphere and bloating the gas cans from the vapor pressure. You can get vapor lock with winter fuel in summer stuff, so I dump it all before mowing season starts.
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#4425981 - 06/08/17 02:18 PM Re: Makita 4 Cycle Trimmer - any mechanics on here? [Re: doitmyself]
m21bmr Offline


Registered: 07/14/14
Posts: 10
Loc: Alabama, USA
Like doitmyself, I would guess it might be ignition coil. I once had a 2-cycle Homelite hedge trimmer that would start and run well when cold, but once it was warm it was almost impossible to get restarted. I don't remember it dying while running, but if you shut it off, or ran it out of fuel, much of the time it had to cool off before it would restart.
I eventually swapped another ignition coil on the engine, and the hot start problem went away. You might check with your dealer. Sometimes manufacturers have a longer warranty on the ignition system.
Good luck getting it running well again.


Edited by m21bmr (06/08/17 02:19 PM)

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#4426010 - 06/08/17 02:59 PM Re: Makita 4 Cycle Trimmer - any mechanics on here? [Re: Kamele0N]
Rab6715 Offline


Registered: 12/02/16
Posts: 72
Loc: Midwest
Originally Posted By: Kamele0N
Check if there is any air leak between carburetor and cylinder...spray wd40 in between when it will be running...if engine will quit...then it is gasket...


Thanks ill try that

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#4426011 - 06/08/17 02:59 PM Re: Makita 4 Cycle Trimmer - any mechanics on here? [Re: MichiganMadMan]
Rab6715 Offline


Registered: 12/02/16
Posts: 72
Loc: Midwest
Originally Posted By: MichiganMadMan
Any chance it is running on winter fuel?

Years ago I came home on a unusually warm spring day to find all my gas cans looking like weeble-wobbles in my garage from all the butane trying to return to the atmosphere and bloating the gas cans from the vapor pressure. You can get vapor lock with winter fuel in summer stuff, so I dump it all before mowing season starts.


Fuel was pumped in April 2017, I always mix stabil with fresh fuel when its pumped.

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#4426012 - 06/08/17 03:01 PM Re: Makita 4 Cycle Trimmer - any mechanics on here? [Re: m21bmr]
Rab6715 Offline


Registered: 12/02/16
Posts: 72
Loc: Midwest
T
Originally Posted By: m21bmr
Like doitmyself, I would guess it might be ignition coil. I once had a 2-cycle Homelite hedge trimmer that would start and run well when cold, but once it was warm it was almost impossible to get restarted. I don't remember it dying while running, but if you shut it off, or ran it out of fuel, much of the time it had to cool off before it would restart.
I eventually swapped another ignition coil on the engine, and the hot start problem went away. You might check with your dealer. Sometimes manufacturers have a longer warranty on the ignition system.
Good luck getting it running well again.


Thanks. I might meter the coil when warm to see what resistance it has. The normal warranty is only 2 years, but your right for the coil it might be longer...

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#4426051 - 06/08/17 04:07 PM Re: Makita 4 Cycle Trimmer - any mechanics on here? [Re: Rab6715]
bioburner Offline


Registered: 09/19/16
Posts: 1418
Loc: Minnesota
I have a 2 cycle lawnboy mower that when the coil starts getting weak will do as your Makita. I have replaced the coil now 3 times since I bought it in 2003
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#4426087 - 06/08/17 04:48 PM Re: Makita 4 Cycle Trimmer - any mechanics on here? [Re: Rab6715]
dave123 Offline


Registered: 01/13/09
Posts: 2314
Loc: wi
Coil

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#4426090 - 06/08/17 04:51 PM Re: Makita 4 Cycle Trimmer - any mechanics on here? [Re: bioburner]
dave123 Offline


Registered: 01/13/09
Posts: 2314
Loc: wi
Originally Posted By: bioburner
I have a 2 cycle lawnboy mower that when the coil starts getting weak will do as your Makita. I have replaced the coil now 3 times since I bought it in 2003
lol just delivered in my hands today coil for my lawn boy it's on its 3rd one quick simple job at least.

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#4426121 - 06/08/17 05:39 PM Re: Makita 4 Cycle Trimmer - any mechanics on here? [Re: Rab6715]
Linctex Offline


Registered: 12/31/16
Posts: 6148
Loc: Waco, TX
Two year old Jonsered CS2245 and I just replaced it's coil. Very bummed about that!!!
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#4426456 - 06/09/17 02:15 AM Re: Makita 4 Cycle Trimmer - any mechanics on here? [Re: Rab6715]
Buzzsaw Offline


Registered: 08/20/03
Posts: 455
Loc: Ga
I'd say bad coil.

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#4426645 - 06/09/17 09:30 AM Re: Makita 4 Cycle Trimmer - any mechanics on here? [Re: Rab6715]
meep Offline


Registered: 02/20/07
Posts: 3556
Loc: Southeast
what are the chances it's running rich/flooded on hot restart?
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#4426753 - 06/09/17 11:32 AM Re: Makita 4 Cycle Trimmer - any mechanics on here? [Re: meep]
Rab6715 Offline


Registered: 12/02/16
Posts: 72
Loc: Midwest
Originally Posted By: meep
what are the chances it's running rich/flooded on hot restart?


Its possible, however, since the carb is not adjustable there is no way for me to test this. I looked at coils, they are surprisingly cheap for this unit, around $15.00 I thought they would be like $40-50. I'm either going to replace the carb or the coil. I might start with the coil replacement since that is going to be cheaper. Is possible i need to adjust the needle in the carb. I might check that prior to ordering a coil. Seems odd that it would only flood when warmed up? I would think it would flood it right away, but it runs fine on cold starts...

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