Oops.  See if the tip of the high screw has broken off in the carb, if it has you'll be looking at a new carb for certain. Some of the after market ones are ok and much cheaper than the OEM ones.

Also if you do get them going and your customer doesn't use them much then tell him to buy and run them on ASPEN 2 or Stihl MOTOMIX. 

Oh dear! The same friend dropped in a leaf blower today and asked about his strimmer. During my explanation, I asked if anyone had looked at the machine. I learned that he had tightened up the high and low screws, and I think he over-tightened them. I can get it running, but it will not idle properly, regardless of what adjustments I make. It also revs for 15 seconds and dies 

Quote from: Mick on July 15, 2026, 02:28:29 PMSounds like you still have a carb issue to be honest.  It's usually the ones that haven't been used much that suffer worse from fuel issues.

I would usually give them a sonic clean before reassembly, but I realise not everyone has that facility to hand.  It also doesn't work every time, but That's what I would do before throwing more money at it..

Also make sure the gasket between carb and manifold is correct and the correct way around so the pulse hole isn't restricted.

Might be a daft question, and I don't want to insult you. But did you get the gaskets and diaphragms in the right order and the correct way around ?  https://www.lsengineers.co.uk/stihl-fs70-carburetor-c1m-s208-c1m-s146-california.html

Trust me Mick, I have made the mistake with the gaskets in the past  They were fitted in the correct order on this occasion.

I think I need to remove the car and try a clean. I don't have a sonic cleaner unfortunately 

No need to feel guilty.  I had loads of used parts kicking around at some point, mind you I could never find them when I needed them and ended up sourcing new ones.

It's called Sod's Law. 

Sounds like you still have a carb issue to be honest.  It's usually the ones that haven't been used much that suffer worse from fuel issues.

I would usually give them a sonic clean before reassembly, but I realise not everyone has that facility to hand.  It also doesn't work every time, but That's what I would do before throwing more money at it..

Also make sure the gasket between carb and manifold is correct and the correct way around so the pulse hole isn't restricted.

Might be a daft question, and I don't want to insult you. But did you get the gaskets and diaphragms in the right order and the correct way around?  https://www.lsengineers.co.uk/stihl-fs70-carburetor-c1m-s208-c1m-s146-california.html

I feel guilty because I had a gearbox from an older HYM46 on my shelf. I retired and a lot of things were scrapped 

A friend dropped off a Stihl FS70, complaining of starting issues and difficulty keeping it running once it started.

It's only been used about 10-15 times since new and is in good condition. I stripped it down and did the usual fuel filter after filling it with fresh fuel. The purge bulb felt strange, and I discovered the metering diaphragm was very stiff. I removed it, and the gasket also looked poor.

I replaced both, and it started, but only on choke. If you release the choke, it settles, but it bogs down after a short time. I checked the exhaust, and it is fine.

It seems to be a fuel delivery issue, and it only runs on the fuel provided after a purge.

Could it be a carburettor issue? The machine is like new, which is why I am uncertain whether the carburettor is causing the issue.

It's stumped me to be honest.

Perhaps my brain is addled and I'm too old for this stuff 

All thoughts are welcome

Changy

Thank you.

Hi Ropi Jo, and welcome to TGMForum.

Regarding the Silicone hose.  Unless it's rated for use with petrol I wouldn't trust it. There's different types of this stuff, but if you use one not suitable for petrol it can soften and swell up, and eventually break down completely.  I would recommend getting hold of some proper fuel line either from your local dealer, or online.

The shroud. If you mean the whole shroud / cowling that surrounds the flywheel and covers the cylinder then yes it needs this to direct the air over the cooling fins etc. Running without it for more than a minute or two can / will result in damage.

And as you mentioned, it's not safe and you could lose fingers or if something falls in while running such as a spanner socket etc you could end up knocking a coil off the block.

Hope this helps. 

I've got 2 general questions please...

1. Fuel line.... on a gravity feed to a briggs  engine, is heavy clear sililcon pipe safe? Or will the petrol eat it?

2. On the same engine... briggs 8.5HP, the shroud / cowling is missing from around the fan / flywheel. Regardless of safety concerns.... is this cowling crucial for cooling / airflow?

Thanks.