stihl 028 super leaning out

[MustangMike]

If any dirt got past that am filter and into the carb, it could be causing the problems.

Also, double check the lever in the carb is set correctly. I saw one that was only about 1/16" off, and it completely killed a 660 in the cut, saw ran great till you put it in the wood, then Blaaaaaa.

 

[huskihl]

Since we're checking obvious things, have you tried opening the H screw 1/4 turn?

 

[Mastermind]

Aftermarket Stihl type fuel filters have been known to me not to flow enough fuel.

 

[drf256]

I still bet carb, but have you looked at the piston and done a compression check?

Sounds like the metering side of the carb is filling and then getting sucked dry before it can fill again. Make sure your needle and seat look ok. I'm sure you replaced the little screen on the pump side?

If you have a ton of carbon and really high compression, it's possible you're losing high tune after a cut. It seems like it's happening a bit too fast for that.

I abandoned my 028S cause of a wandering high tune. I never thought to run without the airfilter as I now think the flap may be pulling shut.

 

[kkemp]

I still bet carb, but have you looked at the piston and done a compression check?

Sounds like the metering side of the carb is filling and then getting sucked dry before it can fill again. Make sure your needle and seat look ok. I'm sure you replaced the little screen on the pump side?

If you have a ton of carbon and really high compression, it's possible you're losing high tune after a cut. It seems like it's happening a bit too fast for that.

I abandoned my 028S cause of a wandering high tune. I never thought to run without the airfilter as I now think the flap may be pulling shut.

Piston looks good . Has 170 lbs compression.

 

[kkemp]

Since we're checking obvious things, have you tried opening the H screw 1/4 turn?

Yep tried that .

 

[huskihl]

Could squirt some carb cleaner around the intake, impulse, and the side of the carb and pay attention to a change in idle rpm. I have a jred 670 with a worn throttle shaft. Carb cleaner sprayed on the left side throttle shaft would kill it. Remedied with a very tiny o ring

 

[MustangMike]

Aftermarket Stihl type fuel filters have been known to me not to flow enough fuel.

Mine were OEM, but had been in there a while. When the saw runs good, you just don't think of changing it.

 

[kkemp]

Just discovered it's blowing gas back out of the carb . When I put the new piston in i done a base gasket delete could that throw the timing off enough to cause that ? Although it ran good for a while .

 

[Stihl John]

I had a similar problem with an 028 I was working on. Had just rebuilt the carburator and could not get it to run right. Finally had to change the black pump diaphram to the blue one and it would run. Make sure your needle lever is adjusted also.

 

[MustangMike]

Make sure you ignition timing did not move.

 

[huskihl]

If the saw cleans out when revved up, I'd say spit back is normal. There's always a possibility something isn't right tho

 

[Basher]

I still bet carb, but have you looked at the piston and done a compression check?

Sounds like the metering side of the carb is filling and then getting sucked dry before it can fill again. Make sure your needle and seat look ok. I'm sure you replaced the little screen on the pump side?

If you have a ton of carbon and really high compression, it's possible you're losing high tune after a cut. It seems like it's happening a bit too fast for that.

I abandoned my 028S cause of a wandering high tune. I never thought to run without the airfilter as I now think the flap may be pulling shut.

If the choke flap pulls closed at WOT the saw runs rich, just like it does to get a cold saw started, at least on the saws I have dealt with.

 

[Stump Shot]

Think at this point, I would get inside the carburetor, the answer most likely to be in there. Could pull a vacuum on the fuel line with filter attached first(out of the fuel), would not be the first defective one(either). Then pressure check the tank, last 028 Super I worked on, had tuning issues, the tank vent was bad. A piece of fuel line and a vent for an echo trimmer was the cure. Good luck, it's in there somewhere, keep looking and checking things, even if twice. SS

 

[kkemp]

Well i put a carb i knew was good on it and that seemed to fix the problem . So I'll probably just get a new carb for it . I sprayed a little carb cleaner around the throttle shaft and it died instantly. Those chinese ones are pretty cheap so I'm not gonna mess around long on this one .

 

[Basher]

..

 

[Duane(Pa)]

I have an 028 with base gasket delete & muffler mod. Really woke it up. I like running it, although I have faster saws that weigh the same. The proverbial brick sh1thouse...

 

[Chainsaw Jim]

Could squirt some carb cleaner around the intake, impulse, and the side of the carb and pay attention to a change in idle rpm. I have a jred 670 with a worn throttle shaft. Carb cleaner sprayed on the left side throttle shaft would kill it. Remedied with a very tiny o ring

Have you seen what most carb cleaners do to black rubber?

 

[Duane(Pa)]

Have you seen what most carb cleaners do to black rubber?

Right....WD 40 is quite a bit more inert and proves the same leaks.

 

[kkemp]

Right....WD 40 is quite a bit more inert and proves the same leaks.

I've used the carb cleaner method on regular small engines . I only sprayed on the throttle shaft I hope none got on the impulse line . I've heard it takes quite a bit cleaner to hurt black rubber but it probably isn't a good idea anyway .