066 RPM's creep up at WOT, ? about fuel filter

[Man of $tihl]

I am having the same problem with my 440. I have a carb kit, fuel line, and fuel filter on the way. Idles fine but when in the cut for an extended amount of time. It leans out and over revs. I was hoping the diaphragm was stiff and not letting enough fuel in. So I'm going that rout first. Hopefully we can figure something out here.

 

[sachsmo]

Back in the days of carburetors, most had a kind of compressed brass nugget type of filter on the inlets.

They still use this type of brass on air mufflers., Wonder if one of those could be mated to a barb and used as a filter?

Dunno if it would catch that fine stuff or not. Sure sound like you have a fuel starvation issue.

 

[J.W Younger]

Back in the days of carburetors, most had a kind of compressed brass nugget type of filter on the inlets.

They still use this type of brass on air mufflers., Wonder if one of those could be mated to a barb and used as a filter?

Dunno if it would catch that fine stuff or not. Sure sound like you have a fuel starvation issue.

Ohyea, those sintered bronze filters would stop it allright.
Then the fuel pump pressure would push the spring behind em back and trash would get under the needle valve and you had a flooded eng.
I dare you to find and old holley without dents in the float bowls from being beat on.

 

[sachsmo]

How about the old Rochester Quadrajet?

Burned up a pretty nice Oldsmobile back in the day.

 

[mtngun]

How about the old Rochester Quadrajet?

Yep, I had to make brass bushings for my Q-jet's throttle shaft.

 

[J.W Younger]

How about the old Rochester Quadrajet?

Burned up a pretty nice Oldsmobile back in the day.

same thing, only answer was pull it out and put an inline in.

 

[spudulike]

Possibly worth checking the height of the needle arm and the condition of the diaphragm, it is possible there isn't enough fuel in the metering section of the carb on a long run of WOT. It may be worth increasing the height a little to get more fuel in to this part of the carb and retune the carb.

 

[mtngun]

Carb inlet screen from my 084. It has roughly 6 tanks of fuel through it. Was using the same aftermarket fuel filter as the 066.

It's not totally plugged up, but it was getting there.

 

[shawn022]

The inside of the stihl filter is a ceramic type cylinder. I just had an 023 come back from a friend. It wouldn't stay tuned at WOT. It turned out to be a small air leak between the clam shell halves. I had replaced the filter before with a Baileys filter. This time I decided to replace the fuel line as preventive maintance. The Baileys filter came apart when I removed it from the line and I saw that foam center. Needless to say it went into the trash and was replace with OEM.

 

[RiverRat2]

Carb inlet screen from my 084. It has roughly 6 tanks of fuel through it. Was using the same aftermarket fuel filter as the 066.

It's not totally plugged up, but it was getting there.

That fuel inlet screen looks knarley for 6 tanks,,,

Hey Do you live over by Booker dog???

 

[Man of $tihl]

I tore my carb apart again and found a semi plugged inlet screen also. I then took my fuel filter off and its an after market orange one with foam inside. Hmmmmm. I'm seeing a pattern here.

 

[mtngun]

Hey Do you live over by Booker dog???

I'm in Idaho, not really close to anyone on AS. There's maybe a half dozen AS members within 100 miles of me that I know of.

Update on the 066 "ghost" problem. I took it to the woods this afternoon, made about 9 passes on a 12 foot log. I checked the WOT at the end of almost every pass. It's still creeping up, though not as bad as before. I tried to keep it tuned to 11,000 - 12,000, to avoid frying another top end. So maybe taking out the clogged inlet screen helped, but I'm not convinced it's the whole story.

Also, I had to increase the idle speed several times over the course of the day. That didn't seem right.

H needle is about 1 1/2 turns out, which doesn't seem right. Seems like 3/4 - 1 turn is more typical for this saw ?

New stuff to check:

-- welch plug. Haven't done it recently because 1) I did it last year and 2) welch plug is for the idle circuit, and I hadn't noticed an idle problem until today. But...... the idle circuit contributes to the high speed mix, and what with the crap aftermarket fuel filter, I wouldn't be surprised to find the idle circuit plugged up.

-- I'll check those throttle shafts, as someone suggested.

-- I'll do yet another leak test, even though it's been leak tested over and over again.

-- I'll order another fuel line, though this one is less than a year old and I doubt it is collapsing what with the non-restrictive aftermarket filter.

-- Haven't ruled out that the H needle is vibrating loose. It may need a fresh o-ring, or perhaps I can rig up some kind of temporary fix, just to rule out that possibility.

I've got a feeling the 066 is going to need another top end by the time this is all done, which is not a huge deal since I have a used BB jug laying around, just darned frustrating and humbling. :bang: But I'll put off the next top end as long as possible because I want to fix the ghost problem first ! :msp_mad:

Meanwhile, my 084 spun the flywheel side seal and red loctite didn't hold so it's going to have to come apart for a sleeve, I reckon. My 84cc kita refuses to start or even pop. I'm getting my butt kicked by saw problems. :hmm3grin2orange:

 

[NORMZILLA44]

Just caught the tail end of this thread, but anything with 066-660 in it catche's my eye. That suck's man, I hate chasing gremlin's, and basket case stuff. Been down that road before. How many new carb kit's has the carb seen? I have seen it before where carb's have to be replaced. I just replaced the filter, and line's in mine. The shop did a carb kit on my request. Still dind't get it, Eccentric say's impulse line. My shop agrees. My 2101 wouldn't hold a tune, and idle was high then low. When I first got it. The saw shop even tune'd it in wood right in front of me, ran beautifull. Went to use it 3 day's later it did a 180, and fast idle started to race. Help from guy's heere siad crank seal. My shop found it, and fixe''d it. Good luck man that stuff make's you want to pull your'e hair out.

 

[Justsaws]

Putting it out there because of two saws that I recently picked up described as "racked with gremlins".

1. One of the saws had a leak in the crank seals that only showed up at WOT and even then was just enough to influence a "creep" of RPMs. Saw would idle smooth forever, transfer from idle to high properly and run at WOT properly for short duration cuts, limbing etc. However, bucking was a different story, it would creep up everytime. Bearings felt great and it passed a pres/vac, already had new OEM seals and new P/C(damaged again) installed under warrenty.

Replaced bearings and seals, cleaned up P/C, problem solved.

2. The other had a "modified" carb and during WOT the screws would rotate the high in and the lo out.

Replaced carb, actually seven carbs but eventually found a good one. Very little needle movement but enough to cause problems. Some of the carbs the movement was very noticeable.

 

[mtngun]

Replaced carb, actually seven carbs but eventually found a good one.

Only seven ? :msp_tongue:

 

[7hpjim]

Hey mtgun, good news, I started the thread about the low hour 395xp with the same problem, SOLVED!!!!guess how!!

 

[NORMZILLA44]

Crank seal's can do word thing's, and cause alot of different problem's, for sure. My saw shop gave me a replacment filter from Stihl for the 660. It is smaller than what was in it. They said it is the standard replacement, and reassured me, when I asked about the smaller size. Should it be a concern?

 

[mtngun]

Update from Grande Dog on the fuel filters:

Hey mtgun, good news, I started the thread about the low hour 395xp with the same problem, SOLVED!!!!guess how!!

Glad the new carb fixed your problem. All it takes is money ..... :msp_tongue:

My saw shop gave me a replacment filter from Stihl for the 660. It is smaller than what was in it. They said it is the standard replacement, and reassured me, when I asked about the smaller size. Should it be a concern?

Dunno, Normzilla44. Don't suppose you have a part # ? As far as I know, the 3504 filter is still the latest and greatest for the big Stihls, but I don't have all the tech memos so maybe they did introduce a new one.

No progress on my part, things happen slow around here. :cool2:

 

[albert]

Maybe hold off running w/o the screen in the carb. I'd hate for you get something hung in a small carb passage and add to your trouble. Do you have access to a ultrasonic cleaner? I hope you get the Stihl filters soon. You'll find not much will get by them.

 

[mtngun]

Broke a clutch spring on the last outing, so it's down for parts, which is just as well till I get the ghost problem figured out.

As I predicted, the dealer did not have an OEM filter, but Grande Dog is sending me the supposedly good Bailey's filters.

I pulled the welch plug, and it was clean as a whistle.

Ultrasonic on order.

Throttle shaft seems to be a normal fit in the housing, no visible gap or play.

Will have to think about this some more as I'm out of brilliant ideas.