Stihl 088 carb problem

Raj

TreeHouser
Joined
Oct 26, 2013
Messages
7,834
Location
Brantford, Ontario
My 088 was acting up. kicking back when cold. Then it would loose power and die in a cut. It would idle no problem. When reving no load it would sound great, no sputter or hesitation. Spark plug is a nice brown ashy colour with some light black oil around the threads, I do run 40:1 oil.

I put in a carb kit but there was one small brass plug I didn't change and a screw in nozzle that I didn't touch.
Ran good for a few heavy cuts.

Now today it seems to over rev, the speed doesn't match the throttle and when you release the throttle it will drop RPMs to a higher idle, then within seconds rev down to idle. Saw will idle and rev no problem, no cutting.

Whole carb is not available in my area.

Any idea what I missed when i put the carb kit?
 
Almost sounds like an air leak or split impulse pipe. I presume you have pressure tested the machine?
The 200t carbs used to develop a similar problem - welch plug was often the cause (that and the accelerator pump, which I don't think the 088 has). It may be the issue allowing air in. Simple way is to use something like nail varnish to seal it & then test again.
 
  • Thread Starter Thread Starter
  • #3
No pressure test yet.

I did discover the new diaphragm was bent up. Hope that's the issue. Dealer has a new kit coming tomorrow, otherwise I'll try to bend it back.
 
Does it make a pulsing sound too after you let off the throttle? We have saw like that. I keep forgetting to richen it. It doesn't kick, but can be hard to start and keep going at times as it leans out and dies at idle.
 
  • Thread Starter Thread Starter
  • #6
No, just a smooth engine bog. Idles fine and throttles great no load.

Thanks all. Going to make plates for pressure testing tomorrow. Dealer has some replacement parts for me. Hope I solve this. Damn milling is backlogged.
 
  • Thread Starter Thread Starter
  • #7
Pressure test. Held 6psi for more than 5 minutes. Pressurized through impulse line.

Metering diaphragm was bent up bad in the carb kit. It didn't push the meter arm down far enough?

Edit. Saw held a vacuum no problem.


20181109_125029.jpg
 
  • Thread Starter Thread Starter
  • #9
Dealer got a whole new kit for me, sold at cost because of the other new kit had the bent diaphragm.


Edit: cylinder compression easily reached 150psi.
 
  • Thread Starter Thread Starter
  • #10
A Facebook page mentioned that cracks tend to develope in the plastic angle fuel inlet, sucking air. Seems it's not a separate part. Mine has a small crack. What can be done? Rubber extension?

20181111165535322d0c32d7d0dd68.jpg
 
  • Thread Starter Thread Starter
  • #15
I'll put a dap on, wrap some metal around it.

New fuel filter just came in, hope it's all solved. Did a couple passes, one on some white oak and a spruce board for a custy.

20181112_161741.jpg
 
  • Thread Starter Thread Starter
  • #16
I have not epoxyed the crack yet. I hate to say I think my fuel filter was a big issue that I over looked. Carb did have some crud in it, and damaged carb kit didn't help, nor the long delivery time for parts. I hope I have it fixed. Milled a 9ft long white oak no problems today, RPMs matched the throttle.

Going to look into a tach to mount on the saw when milling.

I tend to stay away from cheap filters, any good sources for decent aftermarket fuel filters?
 
  • Thread Starter Thread Starter
  • #18
Now it seems my second 088 has carb problems. Took the carb apart to find little plastic like pieces. Looks like someone used epoxy on a welch plug! Hope to fix it Monday.
 
  • Thread Starter Thread Starter
  • #19
Some epoxy over the large welch plug?? Carb is easier to tune now, with it removed and cleaned up.



20190805_124642.jpg
 
  • Thread Starter Thread Starter
  • #21
Bump.

New issue, my second 088 broke the crank somehow, finally got a new to me one, put the saw back together, new gasket, seals and bearings, cleaned up and lightly oiled (with 2 stroke oil) cylinder, rings and piston. Started up great then died. Now it floods, I was hoping thoughts and prayers will work, so I'll ask for them. Try again tomorrow, both arms and shoulders are sore, the saw has a lot of compression now, for some reason.

If the thoughts and prayers don't work I guess it's going to need the carb taken apart.
 
I’d just get rid of it ... send it to me and I’ll use it as a boat anchor ... Besides according to @Nutball STIHL is “lacking” in the torque department 😂
 
  • Thread Starter Thread Starter
  • #25
I did set it to spec, I hope.

Thoughts and prayers didn't work, so carb work tomorrow I guess. Still floods.

I'm thinking of taking and old bar, beefing it up and make a mount to a bench, may be a little easier to pull start and trouble shoot the 088s.
 
Back
Top