Chainsaw hard to start.

[tomalophicon]

Hi experts,
I have a Shindaiwa 577 that I'm having some trouble with.
It won't start when cold and seems to instantly flood. I can start it by using the throttle lock on full throttle then it runs fantastically and will restart when warm on the 1st pull. Again impossible to start when cold.
I have a new plug (getting strong spark), cleaned and put a carb kit through it, cylinder and piston both look great and there is compression. Fuel line, impulse line and breather all look OK and I've blown out the breather.

The only thing I haven't done is put brand new fuel through it.

Any advice on where to go next?

thanks very much.

Tom.

 

[Huskybill]

How’s it idle? Too high of an idle can cut off the choke from working.

 

[tomalophicon]

How’s it idle? Too high of an idle can cut off the choke from working.

It idles perfect once running.

 

[Chainmale]

It's normal to need the throttle lock on for starting.

 

[tomalophicon]

It's normal to need the throttle lock on for starting.

In this case the saw never burps on choke and it takes 20 pulls with the throttle pinned before it smokes and splutters into life.

 

[SimonHS]

Put brand new fuel through it. Your mix could have gone off.

 

[J D]

+1 on fresh mix.
Are you sure the choke is working fully & throttle lock working?
I'd also replace the lines, if the fuel line has a pinhole or isn't sealing on the carb it may not noticably affect running but allow air into the line & fuel to bleed back into the tank over time.
When you rebuilt the carb did you replace the metering diaphragm? Check the metering height? Put gasket on under the diaphragm?

 

[tomalophicon]

Put brand new fuel through it. Your mix could have gone off.

Will do!

 

[tomalophicon]

+1 on fresh mix.
Are you sure the choke is working fully & throttle lock working?
I'd also replace the lines, if the fuel line has a pinhole or isn't sealing on the carb it may not noticably affect running but allow air into the line & fuel to bleed back into the tank over time.
When you rebuilt the carb did you replace the metering diaphragm? Check the metering height? Put gasket on under the diaphragm?

Ok I will try the lines. thanks.

Yes I replaced all diaphragms, gaskets as per IPL and checked the metering height.

 

[tomalophicon]

Another thing I forgot to mention is that more often than not when first pulling using the choke I'll get a pop out the exhaust. Could this be a sign of a too-rich low setting?

 

[Jasent]

Soon as you get that pop switch to high idle. Other wise it will flood out fast

 

[tomalophicon]

Soon as you get that pop switch to high idle. Other wise it will flood out fast

Thanks. That's what I've been doing.
The pop is more like a bang (explosion, like a car backfiring) with visible white smoke from the exhaust.

 

[Jasent]

How many pulls on choke till it pops

 

[Old2stroke]

Confusing. You say it won't start cold and then say it WILL start cold if you use the throttle lock? The reality of 2-stroke engines is they will almost NEVER start cold with a closed throttle. Proper starting procedure when cold requires the choke to be completely closed and the throttle to be advanced to fast idle, some saws have the throttle interlocked with the choke lever so that the throttle is automatically latched partially open when the choke is closed, sounds like yours has the button on the rear handle to do this, but whatever the method, the throttle MUST be partially open for cold starting. If your saw is prone to flooding, try pulling it over only a few times with the choke on (don't wait for it to pop), then get the choke off, leaving the throttle open and try pulling again. If the saw floods too easily, the height of the carbs inlet valve control lever should be checked.

 

[tomalophicon]

How many pulls on choke till it pops

2 usually

 

[tomalophicon]

Confusing. You say it won't start cold and then say it WILL start cold if you use the throttle lock? The reality of 2-stroke engines is they will almost NEVER start cold with a closed throttle. Proper starting procedure when cold requires the choke to be completely closed and the throttle to be advanced to fast idle, some saws have the throttle interlocked with the choke lever so that the throttle is automatically latched partially open when the choke is closed, sounds like yours has the button on the rear handle to do this, but whatever the method, the throttle MUST be partially open for cold starting. If your saw is prone to flooding, try pulling it over only a few times with the choke on (don't wait for it to pop), then get the choke off, leaving the throttle open and try pulling again. If the saw floods too easily, the height of the carbs inlet valve control lever should be checked.

Thanks for this. I reckon you've got it. I've only ever owned saws with 'automatic' fast idle settings and this one as your correctly guess is the manual button on top of the handle.
Your post prompted me to check the manual and it confirmed that the fast idle setting has to be engaged in order to start the saw. I will try this tomorrow and report back.
Thanks again.
Tom.

 

[tomalophicon]

Confusing. You say it won't start cold and then say it WILL start cold if you use the throttle lock? The reality of 2-stroke engines is they will almost NEVER start cold with a closed throttle. Proper starting procedure when cold requires the choke to be completely closed and the throttle to be advanced to fast idle, some saws have the throttle interlocked with the choke lever so that the throttle is automatically latched partially open when the choke is closed, sounds like yours has the button on the rear handle to do this, but whatever the method, the throttle MUST be partially open for cold starting. If your saw is prone to flooding, try pulling it over only a few times with the choke on (don't wait for it to pop), then get the choke off, leaving the throttle open and try pulling again. If the saw floods too easily, the height of the carbs inlet valve control lever should be checked.

Well I feel like a ******** but you solved my problem. Operator error.
She cracked into life first pull with throttle lock engaged and choke closed.
Cheers again mate!

 

[Old2stroke]

It's all good, many more people are having trouble with starting a hot saw because they don't understand the importance of throttle position. If a saw is hot and properly tuned and only been turned off for a few minutes, it should start with one pull without touching the throttle or choke. If it doesn't start after 3 pulls, it probably isn't going to start until the throttle is opened to the fast idle position, and with modern saws using a master control lever, there is a lot of confusion about how to set it to fast idle with no choke.

 

[rupedoggy]

Read the owners manual? Who does that?????????

 

[grizz55chev]

Read the owners manual? Who does that?????????

You crack me up, lol!