Strimmer starting issues

[ipbr21054]

Numerous pulls but won’t start.
I normally have the choke on until it tries to start.
I then take choke off hold throttle down & pull to start.

This doesn’t happen now.
Lost count how many times I’ve pulled the cord.
Remove air filter & flash of fuel into the Venturi starts it start away.
Give it a few minutes to warm up then put air filter back on.

Air filter is clean.
Try & Rev it now then it bogs down.
Turn the screw in Rev it no difference turn it in more no difference.
Keep turning in until the point it stalls.
So I then turn the screw out 1 1/2 turns & start it up.
This time I turn the screw out but still won’t Rev without bogging down.

Starting to become a real pain

I’ve even tried to do the same with leaving the air filter off.

 

[Burnerman]

Does the primer bulb readily fill up with fuel when you prime it? You should also see fuel returning to the tank if all is well there.
John

 

[ipbr21054]

Yes it fills up.
yes to fuel returning to tank as i took off the tank cap & could see it happening when bulb was operated

 

[Burnerman]

Fix yourself up with a diaphragm and gasket set, as well as a can of carb cleaner.
Is it a Ruixing carb?
John

 

[ipbr21054]

Didnt take note of the name.

Can you advise what you think is happening.
Why does it bog down ?
Why when i screw it in or out no difference is seen ?
Why will it start with fuel down the venturi but hard even impossible on the pull cord ?

Thanks

 

[Burnerman]

These diaphragms I’m always on about actually pump fuel from the tank, and then meter the fuel to the various jets inside the carb. They do tend to lose their elasticity from time to time and I renew them very frequently. Tipping fuel into the carb does the same job as the pump diaphragm.
The bogging down syndrome can be due to weak or rich mixture unfortunately and it can be hard to tell which,and thats the reason I replace the diaphragms so often.
Setting the mixture screw (s) at one turn out is a good starting point.
John

 

[ipbr21054]

Sorry to drag this up again but still no joy so I purchased another carb.

But issue is the same so I would then rule out the carb is the issue here.

Same with this new carb in respect of pressing the primer bulb say 3 times, choke on them 10 times pulling the cord but not a sign of it trying to start.

I remove air filter & pour some fuel in the Venturi, choke on & pull cord. Starts straight away or say 2nd time.

Can’t see what the issue is.

1, I press the primer bulb and see it fill up & also see the full returning to tank.

2, The inlet fuel pipe which has a filter on is connected to the metal pipe on the carb which just above / inline with it has the mixture screw. So I assume this is on the correct pipe & not fitted the wrong way around.

3, New spark plug fitted.

4, New air filter fitted.

I don’t see why I have the same issue starting it even with a new carb. Starting to be a pain keep taking air filter off to start it then putting it back on each time.

Once started it runs for ages it’s just starting is the issue here.

 

[ipbr21054]

Pressing the primer & seeing it fill up & also returning to the tank how can I check fuel is actually going to where it should be and not just cycling out of tank through primer bulb then back to tank again thus not squirting any for the spark to ignite because this seems to be what’s happening as pouring it in myself it starts straight away.

 

[Burnerman]

I haven't much more to add here, I'm afraid - once the machine starts running proves that the carb connections are correct.
Do check however that any gaskets between the carb and the cylinder are intact - and any holes drilled in the plastic manifold are lining up with gasket holes and any drillings the carb may have.
I'm wondering what sort of condition the engine is actually in....does it have a healthy compression when you pull the engine over?
We are getting into the science of two strokes here but any leaks into the crankcase through the supporting main bearings will cause air leaks and awkward starting. This manifests itself by any play in the bearings (can you rock the flywheel for example) or oil traces on the outside of the engine crankshaft. All must be dry here.
John

 

[ipbr21054]

Forgot to mention all new gaskets fitted when new carb was fitted.
Also at the rear of the engine I removed the cover now being able to see con rod etc & fitted a new gasket here also.
No oil leaks and not sure how to check compression but pulling it with spark plug fitted & removed you can definitely tell the difference.

If I were to swap the fuel lines over are you saying the strummer will just not run ?

Very strange this is.

 

[Burnerman]

For sure, I'm certain that the strimmer wouldn't run if the fuel lines were reversed - but I've never tried it!
Compression test.....thumb over plug hole, pull the starter cord swiftly. Your thumb should be blown from the plug hole if all is well.
Also, take the exhaust off and peer at the piston. Can you see scratches or piston ring damage?
John

 

[Rekusu]

Having a similar problem with a Honda GX25 tiller engine. Nothing I do will start it. Nothing left to check, then for no reason, it started, ran for around 30 seconds, stalled and will not start again.

Ten mins later, started, ran for 20 seconds, stalled and will not start. Totally flummoxed and don't' know what to check.

 

[ipbr21054]

So another couple of weeks down the road and I’m still having to remove air filter & pour fuel in at the start.

 

[Rekusu]

I'm right there with you bro!

Today, figured I would check the metering lever clearance as I found something on the web. Set it, primed the bulb and wow!!! Started on second pull. Brilliant; success.

30 seconds later, it stalled and will not start again.

I'm now becoming and expert at removing and stripping the carb but no further forward. There is one item that i can suggest, that I have forgotten to look at. On my Honda GX25, there is a small breather hole and groove next to the inlet port, and a cut-out leading to the carb. Apparently, this is something to do with exhaust gas returning to the carb for some pressure related function. If this is blocked, then the carb sill not be pumping fuel. I have not checked it yet, but after X pulls of the cord, then removing the spark plug, I have found that the plug is dry, so can only assume that fuel is not getting through.

 

[ipbr21054]

Sounds like fuel isn’t being delivered.
I don’t think Ive checked my plug to see if it’s dry but assuming it is why does the item run for hours once I start it when pouring fuel in the Venturi. You would think the primer isn’t working but it is as I see fuel being sucked up and also returning to the tank.