Stihl 088 carb problem

[SkwerI]

The small metal lever that is moved by the diaphragm and lifts the fuel needle may be bent too high, keeping the fuel supply open too long.

 

[Raj]

I'll have to recheck that. Seems a new carb is not available from Stihl up here.

 

[SkwerI]

When I had mine, it had a Tillotson on it. Available replacement was a Walbro. I kept the Tillotson and put a kit in it.

 

[Raj]

The lever is just a few thou proud of the surface.

 

[SkwerI]

I have no idea where it's supposed to be but somebody does.

 

[Tree09]

Where's the needle valve lever at? You need to make sure it's seating and shutting off flow, I've had it where it wouldn't shut it fully.

 

[Raj]

I did the pressure and pop off test, held 7psi no problem and popped off at 14 psi

 

[Nutball]

It almost sounded a little lean at idle to me.

 

[Raj]

I got it to run, I wanted to do more carb adjustments but it flooded on me again.

 

[Raj]

http://thebakeliteradio.com/sawspares.com/stihl%20carburetor%20manual.pdf

 

[Raj]

I can get the saw to run, or at least burp and smoke then flood, but I have to let it sit for a few days.

 

[Magnus]

Is main inlet needle set right and tight?

Do you run it dry after its flooded and make sure there is nothing left in crank case or Muffler/Intake?

 

[Raj]

The carb holds 7psi steady and pops off at 14psi.

I do take the spark plug out and pull it over on it's side.

 

[Nutball]

You should be able to close the needles and run it dry, then gradually open them until it runs right without flooding, though if it has a bypass jet, then that may not help. I had a wood splitter do similar things. You had to be careful not to use too much choke or too many pulls with full choke to the point of: pulling with no choke, then pulling the cord with gradually more choke. Otherwise you'd risk flooding it or getting hard kick every time you pull the rope if it wasn't already flooded from shutdown the last time it was used. I started lowering the throttle slowly, let it idle, then shut it off to help prevent it from being flooded for the next start. Not long after it needed a spark plug. I don't know how the wood splitter story helps, but it did seem to have a similar problem, though totally different engine.

I wonder if there are any compatible cheapo chinese carbs you could try?

 

[Magnus]

The carb holds 7psi steady and pops off at 14psi.

I do take the spark plug out and pull it over on it's side.

Yes, but is it set correct in height?
If its too high it may leak when you start it. It can still hold tight when testing but flood as its open too much.
What needle setting is it on now when it floods?
Is intake tight?

On side won't do it. Flip it over and pull without plug and kill switch activated.
After that, close fuel and run it dry.
You likely have fuel in muffler too so remove it and burn it dry.

 

[Raj]

What's the correct height? I've been looking for that information.

 

[Magnus]

HT Parts List: https://tillotson.ie/wp-content/uploads/2015/07/HTPartsList.pdf

This is from 084 WS manual. It use HT carb as well.

 

[Magnus]

If you changed membranes it may be different heights on heel on membrane. Just a couple tens of an milimeter will do as then inlet needle is not working right.

Needles should be one turn out on both H and L.
I suspect yours is not.

Then as it runs you fine tune it. No less than 3/4 on any of them and no more than 1 1/4.
If so inlet needle is set wrong and need adjusting. If not saw will not perform correct and risk of damages.

 

[Magnus]

Also take a good look at needle so its coned and no defects or crap on it.

 

[Raj]

I did pressure test the needle, and replaced it anyways. What height should the needle arm/lever be? What pressure should the needle hold?

 

[Magnus]

If you put it together and it is tight with membranes and covers I think that is enough.
Lever is set flush with bottom under membrane. A bit lower if heel on membrane is higher than original.

 

[Raj]

I knew I was half decent at rebuilding carbs. I guess my problem was bad timing.

 

[Magnus]

There you go.
Thats a trixy one to find. Not the first thing you think of or look for.

 

[Raj]

Well now my main 088 started to idle high, sounded like an air leak, then wouldn't idle, I can start it with choke and high idle, soon as I touch the throttle it'll stall out.
Compression is over 130psi, P and C look good.
Saw held vac and pressure for hour with no loss.
fuel line held vac and pressure.
carb was cleaned up and new kit put in, except welch plug.
new spark plug
I ordered a new coil

 

[Raj]

One of my 088s was running a bit funny, could not get the carb tuned, didn't seem to have power. I thought I opened this.carb up before. Guess not.