Problem starting stihl 075

[Hunter]

Also tried this trick.

[agg221]

OK, let's think about what we know.

 

It coughs when the choke is on. That means you have fuel and air at near the right mix, and a spark under compression. It also means you are pulling it over fast enough.

 

When you take the choke off, it doesn't start or even cough, but the plug ends up wet.

 

Some thoughts.

 

Firstly, there are two levers on the back of the air filter cover - one for the choke, the other for the on/off switch. You are leaving the on/off switch in the on position?

 

Secondly, what happens if after it has coughed you set half-throttle, or ideally have someone holding the throttle open, and pull over again without taking the choke off? If it is set too lean, it will start and run happily when choked but not unchoked, as you will then have the mix right.

 

Thirdly, have you had the air filter off and had a look at how clean it is? If it's very blocked they can be extremely difficult to start. If you can't see through the flocking when held up to the light it needs a good wash out.

 

Alec

Edited March 29, 2017 by agg221

[Stubby]

Has your fly wheel key sheared and put it out of time ?

[mixedangased]

Has your fly wheel key sheared and put it out of time ?

 

Might not be set to bst

[billpierce]

Might not be set to bst

Ha!

 

Sent from my C6603 using Arbtalk mobile app

[spudulike]

Couple of things - make sure the throttle lock is actually opening the throttle valve so the bottom of the valve is circa 5mm open.

 

Other than that and more likely, it sounds like your needle is sticking open a bit. Have seen it before, the saw coughs on choke and that is it. Made worse on a big saw like this - worth pulling the decomp and making sure that is working OK just for your own protection.

 

Best to pressure check the carb - should hold up to 10psi with negligible leakage. My money is on a hardened diaphragm keeping the metering arm open or a corroded needle!

 

The kickback is normal on old saws, they have a single set advance on their ignition system - circa 19 degrees but modern saws flip the ignition advance to near zero at under 500rpm to aid starting, up to 21 degrees mid range and then back the advance at max revs.....no such luxury on these old saws!

[Hunter]

I have got it running but only temporarily.

Ok I have tried new spark plug and it made no difference

I have checked air filter and it is clean

I have tried without the air filter and no difference

Throttle lock seem to be working fine

 

The only way I mange to run it was

Drain the whole fuel from fuel tank and cylinder and left it over night

Put a tea spoonful of fuel mix directly in spark plug whole

Spin it couple of time to distribute the fuel

Put the spark plug back and pull the cord chock off and throttle lock on

It did cough twice and run with the third pull

Was steady and lasted for 8 seconds or so but it will not rev then stopped. Not sure of it is suppose to rav woth such little fuel.

Pulled the cord again and it will run with first pull this happen 3-4 times.

But it will not accelerate at all.

Put fuel in the tank and it run again for 5 seconds but will not rev.

Then back to square one as it stopped and couple of more pull and flooded again and plug is wet.

Funny enough it did not kick back at all during the above trial.

I guess this telling me that compression is good, and flywheel key is fine.

I am trying to see of I can get it to work or at least diagnose the problem without taking it a part as if it will not work I am going to return it un touched to the seller.

Edited March 30, 2017 by Hunter

[billpierce]

I have got it running but only temporarily.

Ok I have tried new spark plug and it made no difference

I have checked air filter and it is clean

I have tried without the air filter and no difference

Throttle lock seem to be working fine

 

The only way I mange to run it was

Drain the whole fuel from fuel tank and cylinder and left it over night

Put a tea spoonful of fuel mix directly in spark plug whole

Spin it couple of time to distribute the fuel

Put the spark plug back and pull the cord chock off and throttle lock on

It did cough twice and run with the third pull

Was steady and lasted for 8 seconds or so but it will not rev then stopped. Not sure of it is suppose to rav woth such little fuel.

Pulled the cord again and it will run with first pull this happen 3-4 times.

But it will not accelerate at all.

Put fuel in the tank and it run again for 5 seconds but will not rev.

Then back to square one as it stopped and couple of more pull and flooded again and plug is wet.

Funny enough it did not kick back at all during the above trial.

I guess this telling me that compression is good, and flywheel key is fine.

I am trying to see of I can get it to work or at least diagnose the problem without taking it a part as if it will not work I am going to return it un touched to the seller.

If you intend to return it via eBay/PayPal rules do not do any work or even mention you have changed plug etc. I bought a saw that was supposed to be a good runner and which didn't even spark, I lost eBay dispute as they said I had taken it to bits to see if it sparked. Annoying

 

How old is the fuel you are using?is it ok in other saws?

 

Sure you'll get it sorted, prob worth getting someone to have a look at it as could be something obvious that we/you are missing

 

Or just buy mocks 076 and send it back

 

Sent from my C6603 using Arbtalk mobile app

[billpierce]

*micks

 

Sent from my C6603 using Arbtalk mobile app

[Hunter]

Couple of things - make sure the throttle lock is actually opening the throttle valve so the bottom of the valve is circa 5mm open.!

The Genius got it right. It is the throttle lock, for some reason was not working. I thought I have checked it and it was fine but then I have checked again and despite the cable move it was not doing anything then it sorted it self out.

Once throttle worked I was able to run the saw easily.

I guess still some carb adjustment needed. Saw Rev up very good and engine sounded strong and fine with no smoke.

When saw started with throttle lock the chain will run, when saw idle the chain will not run but the saw will idle only for 2-3 second and then will die.

I guess carb need some adjustment but this Is not a problem.

Thanks for every body who helped me out.