My Stihl 028 AV Super just wont run! please help!

[SuperNate028]

I really feel F'd in the A. i've read close to 10 stihl 028 super forum posts about fixing the start up then die problem. basically memorized the illustrated parts manuel. spent hours taking it apart and cleaning everything i can get to and the sucker just wont idle or run for longer than a popcorn farts instant. Please Help.

This is what i've know. my coil's good (used 2 pieces of paper to measure gap) and i get a hell of a spark when i ran that test. compressions fine. changed the fuel filter, fuel line, impulse line, spark plug, rebuilt carb (twice...D'oh), 'tweaked' the exhaus t and when i took it off i took a peak at my cylinder through the exhaust and it looks smooth (or at least from what i saw on the site of bum cylinders it looked clean. i saw really small lines around it but it shined, and im guessing it'd look the worst towards the exhaust side. do top and bottom of cylinder matter to look at if sides look good?) it'll start up, rev way up and kill itself. i can keep it running by VVVRRRMMMing her hard at a fast pace, eventually it kills itself. I played night and day with the H/L and Idle Screw. white exhaust rolls right out. i've basically feel like it's some air leak i missed somewhere, or the cylinder is disguised as looking good, or the seals. Pretty dang close to bringin it to a local stihl fixer-upper for under $20, but i dont want to give in that easy and where's the fun in that anyway? i've put over 6 hours into fixing my stihl 028 super AVEQ and haven't been able to cut one gosh darn log! Someone PLEASE bust the wall i've ran into.

p.s. one more thing, seems to be spitting bar oil pretty generously out of the bar manifold, is there an oil adjustment screw on a stihl 028 super? i couldn't seem to locate it. my friends stihl 032 you can access it from the bottom.

 

[Moparmyway]

Did you change screens at the fuel inlet inside the carb ?

If you didnt, there is most likely some slime blocking the gas from passing through it and getting into the carb

White exhaust ???? Are you sure it isnt blue-ish ?

 

[SuperNate028]

it filled up my basement with smoke, may have been blue-ish? i remember replacing the screens. oh what mighty fun that was. i did notice a little bit of slime gunk type stuff in it but i put the carb cleaner to all the passages i could find. maybe it'd be worth a third revisit?

 

[revver6]

check fuel and impulse lines for cracks they can be an issue with a saw of that age if you have not already.

 

[SuperNate028]

i replaced all the lines, rebuilt carb, fuel filter, cleaned the coil and re-gapped it w/ flywheel. new spark. great compression. it has some some richer mix in it, but a friend who uses the stihl 032 said it shouldnt be what's causing the problem, though i've read this in many posts about the 028, and getting the mixture right for the fuel.

 

[SuperNate028]

the same friend that told me it's an air leak somewhere. but im really wondering if it has anything to do with the piston and cylinder, but piston looked smooth and shiney from the exhaust port. i've seen pictures of scoring and it didnt look like it had any of that.

 

[SuperNate028]

aint gunna put my tail between my legs and bring it to a stihl guy, heck no!

 

[timbrjackrussel]

How does it run with the air filter off of the saw?

 

[SuperNate028]

would it be any better than the brand new air filter on it? i'll check it out if so

 

[timbrjackrussel]

would it be any better than the brand new air filter on it? i'll check it out if so

If the little spring that holds the choke flap open is gone or not fastened the engine will suck the choke closed and flood it.

 

[SuperNate028]

would this spring be 1/8inch aprox. in diameter and 1/4inch in hight?

 

[SuperNate028]

i removed carb and have it in hand, the spring is attached and working as usual. the flap is shut unless i pull on the throttle arm (to pull it open)

 

[procarbine2k1]

It doesnt sound like an air leak to me. Could be wrong... You said you have rebuilt the carb twice, did you adjust the metering lever and if so per what specs? That small detail has caused me some aggravation in the past, that is for sure.

 

[Stevie-D]

i've got an old 028AVEQ Super. magnesium tank/handle assembly, no chain brake, 42MM piston, had points ignition that has been upgraded, etc... had the same problem with it. rebuilt the carb, tried a carb off a newer saw, made absolutely no difference. the only way i could get it to run was to turn the high screw out about 4 turns. had the same symptoms as yours- racing idle and would only run for 10 seconds max blipping the throttle. When i could get it to stay running for a few minutes, it would die out as soon as i started a cut. it would also shut off immediately when applying pressure to the dawgs or turned on its side for a cut. Seems to me the movement of the AV system allowed the saw to suck air through a leak that was not affected until it moved one way or the other.

The saw is currently completely stripped down. piston and cylinder both look new, fuel line and impulse lines were useable- no tears or cracks that i could notice. My bet is the crank seals are junk. In your case the easiest way to determine that is to have a pressure test done on the saw. If it holds, the problem is somewhere else. I skipped that step because i was tearing the saw down anyway to freshen everything up and planned on replacing all lines, bearings, seals, etc... With a saw that old, chances are if it's not broken now, it will be in the near future.

 

[SuperNate028]

ProCarbine - that's the piece that fits over the spring where the float connects to? it's sitting flush with the metal around it if that is it. I saw inlet lever and metering diaphram (which goes with the gasket above the float)

stevie D - That's the next adventure i plan to journey into. checking the seals and all that. could be my problem. almost everything else on this saw is brand new and the piston looks great.

 

[SuperNate028]

Thank you for all of your help, i really do appreciate the wonders of this forum.

Stevie D - Good compression. just like you said "if it's not that the problem is somewhere else" where on saw earth could it be? any ideas?

 

[Moparmyway]

it filled up my basement with smoke, may have been blue-ish? i remember replacing the screens. oh what mighty fun that was. i did notice a little bit of slime gunk type stuff in it but i put the carb cleaner to all the passages i could find. maybe it'd be worth a third revisit?

That slime gunk is from ethanol and water in your gas. It is now everywhere inside all of your little passages in the carb. You need to remove everything from the carb including any welch plugs and "deep clean" it, blow out every passage, put in new plugs, and re-assemble ........ and even then, sometimes its just best to get a new carb.


Do you live close to anyone that might have a carb you could just try to see if your saw runs well with a known good carb ?


Your symptoms dont really line up with an air leak, but more with just running out of the very small amount of gas thats in the carb. Somethings plugged up in that carb IMHO

 

[Fish]

ProCarbine - that's the piece that fits over the spring where the float connects to? it's sitting flush with the metal around it if that is it. I saw inlet lever and metering diaphram (which goes with the gasket above the float)

stevie D - That's the next adventure i plan to journey into. checking the seals and all that. could be my problem. almost everything else on this saw is brand new and the piston looks great.

Take your carb apart again and dis-assemble. Remove the needle/lever/spring and hold up to a light and look through the passage to
the screen on the other side, then blow out that passage and hold it up to a light again and visually verify that the passage is clear.
Reassemble.

 

[SuperNate028]

totally disassembled my carb, to the exact illustration on the walbro web site. spray a gracious amount of carb cleaner through every little hole i could find. took out the float, lever, spring, that passage looked clean but i sprayed it again, nothing seemed to change inside the passage. I have a buddy that just watched me do it and he said if you put the meter diaphragm on the block, THEN put the gasket on (walbro website shows the opposite order) it will fluxuate more efficiently.

tried firing it up, nothing. wouldnt start at all and now fuel's spewing from behind the muffler. Any thoughts or idea's on this?

Thanks for your time and answers all, 'wireless hospitality'

 

[Fish]

Float!!!!????

Did you read my last post??? Are you the one working onthis saw?