Dang, Tillotson/Homelite has me stumped and mad!

[Modifiedmark]

I made a deal to sell my SuperXL925 to another member and assured him that the saw had been gone through with alot of new stuff and was a good one.

The saw has set some in the last year but never had stale fuel in it and got started now and then. Pulled it out a few weeks ago when I had made up my mind to sell it and fired it up and made a few cuts with it. It ran perfectly like it always had.

Fast foreward a couple weeks and the deal was made and I made ready to ship the saw. I was going to double check that all was good and started the saw one last time before I drained it to package it up.

Well guess what? It now ran like crap! The thing was running bad rich and idleing wierd.

I could not get the carb to adjust out right and it would burble around in the cut with the H needle only 1/4 turn out.

I thought maybe it was a governor problem with the Tillotson HS151B carb since I had never blocked this on off, so I pulled it and blocked it off.

No change. Checked the carb with a fine tooth comb, changed out the inlet lever, needle and metering diaphragm without any more luck with it.

Checked everthing over that I could, ign, fuel plug and whatever I could think of. Nothing helped.

I thought since I promised the buyer a good saw that I would just order a new carb for it but found them to be NLA.

It then dawned on me that unlike most of the HS carbs that I have delt with that this one used a main nozzle with a check valve in it and thought that this could be my problem.

Also looking at the main nozzle I could see light all the way through the nozzle so I thought the check valve might be bad so I went ahead and orderd a new nozzle and governor for it.

Got the parts, installed them and it runs the same! I blocked the governor off again and got the same results!

This saw will only run well with the H screw turned all the way closed...

Where is the fuel coming from to even make it run?


I'm contacting the buyer and letting him know I just wrote the check to send him his money back as I don't feel right with this saw to send to him.

Anyone got any ideas how to fix this carb? I guess I don't know anything about them.

 

[Bowtie]

I have had that problem with other carbs Mark, sadly only fix I found was replace the carb...

 

[pioneerguy600]

Mark, would the welch plug be leaking, that is one thing that can supply fuel even though the H needle is turned all the way in.
Pioneerguy600

 

[Modifiedmark]

I have had that problem with other carbs Mark, sadly only fix I found was replace the carb...

I would gladly do that if I could have gotten one in a fair amount of time.

Mark, would the welch plug be leaking, that is one thing that can supply fuel even though the H needle is turned all the way in.
Pioneerguy600

No, I replaced the only welch plug in it and its over the idle ports. This one dont have a welch plug over the main check valve nozzle.

This new nozzle will show light all the way through it, that shouldnt be should it?

I mean that would let fuel from the metering chamber go right through it/

 

[pioneerguy600]

I would gladly do that if I could have gotten one in a fair amount of time.



No, I replaced the only welch plug in it and its over the idle ports. This one dont have a welch plug over the main check valve nozzle.

This new nozzle will show light all the way through it, that shouldnt be should it?

I mean that would let fuel from the metering chamber go right through it/

A new nozzle should be in the closed position and only open on higher vacuum when the throttle opens, no light should pass through if it is closed. Defective nozzle maybe?
Pioneerguy600

 

[Modifiedmark]

A new nozzle should be in the closed position and only open on higher vacuum when the throttle opens, no light should pass through if it is closed. Defective nozzle maybe?
Pioneerguy600

It was brand new in the Tillotson package, but it would be my luck that 1 bad one in a thousand would end up here.

Thats exactly what I was thinking though, that the nozzle should not allow you to look straight though it. The one I took out you could and thats why I figured it was bad.

Then I had a bad feeling that when I looked at the new one that it wouldnt solve my problem and it didnt.

To be honest though, I never had a nozzle problem before but I have done lots of Tilly HS's without that check valve nozzle and never had this type of trouble with one except one with a bad governor which acted the same way except that it idled fine.

By first installing a new governor then blocking it off I think I have eliminated that from the problem.

Just looking for some confirmation that I shouldnt be able to look through the new check valve nozzle.

 

[pioneerguy600]

Hope some of the real techs can confirm the nozzle operation for sure, my understanding of them is that they are closed until the saw requires more fuel to run WOT and that is when the nozzle opens and delivers extra fuel. If the nozzle is open at idle then the saw would run so rich it would be flooding.
Pioneerguy600

 

[Modifiedmark]

Hope some of the real techs can confirm the nozzle operation for sure, my understanding of them is that they are closed until the saw requires more fuel to run WOT and that is when the nozzle opens and delivers extra fuel. If the nozzle is open at idle then the saw would run so rich it would be flooding.
Pioneerguy600

Not necessarily as when the throttle is closed your only running off of one of the idle circuit nozzles so you it wouldn't flood it out, but it is making the idle uneven and erratic.

 

[pioneerguy600]

Not necessarily as when the throttle is closed your only running off of one of the idle circuit nozzles so you it wouldn't flood it out, but it is making the idle uneven and erratic.

Hope you get it sorted out, I got a couple of those 925`s in a truckload of saws a while ago, have not looked them over as of yet.
Pioneerguy600

 

[Modifiedmark]

Oh I think I'll get it sorted out, sooner or later. I could look and try to find a carb, but then I get stubborn and want to fix this one!

The is just no other reason that I can see for it to be screwing up but for this main nozzle, everything else should be good to go.

Still trying to figure how it could be running good one minute and then run bad the next.

Bad thing is missing out on the sale, but the good thing is that it went to heck before I sent it and have it mess up on the buyer after I promised that it was all good.

 

[Wildman1024]

Pretty much the same thing was going on with my 925. It would start and idle great but as the saw warmed up and the more you ran it you had to continually lean the H out. After making a few cuts with the saw you would go from 1-1/8th out to only 1/2 out on the H to keep it from being overly rich. It was really weird and i could never figure it out. I cleaned and went threw the carb 100 times.

 

[FamilyTradition]

My experience.......

Mark, I have a super clean SXL 925. I had a similar problem and was ready to throw in the towel and make her a shelf queen. I decided to go through the carb one more time and found dust and debris in the screen and elsewhere. Not the same problem as you're experiencing except for the frustration. There were some threads on here that really helped me, possibly written by Gary. Maybe that was for another saw, I don't know. You will figure it out. Step away for a few days and clear your head, and that may help. Good luck and keep us posted. Best, Max.

 

[roncoinc]

I also have been having a problem with an HS carb.
never ran the saw enough to have adjustments degrade but trying to tune the hi end it was cutting out WAY to soon so i blocked the governor,that wasnt it.
rebuilds did nothing.
carb has been living in the USC for about a week now turn it on everytime i walk by.
hope to get to it today and see if problem solved.
will take a look and see if i can see light there.. then see if saw runs good.
Mark,you dont have another carb to put on there ?
didn't i send an HS ?

 

[chainsawlady]

925 Carb

I made a deal to sell my SuperXL925 to another member and assured him that the saw had been gone through with alot of new stuff and was a good one.

The saw has set some in the last year but never had stale fuel in it and got started now and then. Pulled it out a few weeks ago when I had made up my mind to sell it and fired it up and made a few cuts with it. It ran perfectly like it always had.

Fast foreward a couple weeks and the deal was made and I made ready to ship the saw. I was going to double check that all was good and started the saw one last time before I drained it to package it up.

Well guess what? It now ran like crap! The thing was running bad rich and idleing wierd.

I could not get the carb to adjust out right and it would burble around in the cut with the H needle only 1/4 turn out.

I thought maybe it was a governor problem with the Tillotson HS151B carb since I had never blocked this on off, so I pulled it and blocked it off.

No change. Checked the carb with a fine tooth comb, changed out the inlet lever, needle and metering diaphragm without any more luck with it.

Checked everthing over that I could, ign, fuel plug and whatever I could think of. Nothing helped.

I thought since I promised the buyer a good saw that I would just order a new carb for it but found them to be NLA.

It then dawned on me that unlike most of the HS carbs that I have delt with that this one used a main nozzle with a check valve in it and thought that this could be my problem.

Also looking at the main nozzle I could see light all the way through the nozzle so I thought the check valve might be bad so I went ahead and orderd a new nozzle and governor for it.

Got the parts, installed them and it runs the same! I blocked the governor off again and got the same results!

This saw will only run well with the H screw turned all the way closed...

Where is the fuel coming from to even make it run?


I'm contacting the buyer and letting him know I just wrote the check to send him his money back as I don't feel right with this saw to send to him.

Anyone got any ideas how to fix this carb? I guess I don't know anything about them.

I have an instruction sheet put out by Homelite about the HS151A carb.
I will send you a copy The last paragraph says "You may very well find that maximum power occurs with the HI Needle
almost closed or completely closed, because the carburetor is designed to meter the fuel for high speed operation automatically.
chain saw lady

 

[lesorubcheek]

Mark, is there any chance the metering needle isn't seating perfectly? Could be some small debris in the seat or a small amount of corrosion. May be worth a pop-off test to see if its holding at all. If its seeping, that may explain the problem. Sounds like you've covered most of the bases already. Sure you're gonna figure it out soon enough.

Dan

 

[cbfarmall]

I have an instruction sheet put out by Homelite about the HS151A carb.
I will send you a copy The last paragraph says "You may very well find that maximum power occurs with the HI Needle
almost closed or completely closed, because the carburetor is designed to meter the fuel for high speed operation automatically.
chain saw lady

Mark,

Joyce is on to something here. While just a Stihl, my 056 MagII has a semi-adjustable hi-speed circuit Tillotson. Check out the adjustment sticker on the cover. Why your carb's behavior has changed over the past year is anyone's guess.

Chris B.

 

[Modifiedmark]

I have an instruction sheet put out by Homelite about the HS151A carb.
I will send you a copy The last paragraph says "You may very well find that maximum power occurs with the HI Needle
almost closed or completely closed, because the carburetor is designed to meter the fuel for high speed operation automatically.
chain saw lady

Yes please do! It might keep my hair from getting more grey. It might make some sense out of it!

Maybe you could scan it and post it here, but if not and you send it to me I will do that for the benift of the rest of the members.

Mark, is there any chance the metering needle isn't seating perfectly? Could be some small debris in the seat or a small amount of corrosion. May be worth a pop-off test to see if its holding at all. If its seeping, that may explain the problem. Sounds like you've covered most of the bases already. Sure you're gonna figure it out soon enough.

Dan

No the needles holding pressure fine. Carb is clean and as tight as a new one.

I also have been having a problem with an HS carb.
never ran the saw enough to have adjustments degrade but trying to tune the hi end it was cutting out WAY to soon so i blocked the governor,that wasnt it.
rebuilds did nothing.
carb has been living in the USC for about a week now turn it on everytime i walk by.
hope to get to it today and see if problem solved.
will take a look and see if i can see light there.. then see if saw runs good.
Mark,you dont have another carb to put on there ?
didn't i send an HS ?

Yes you did but the older Poulan style 59A carbs are quite a bit differnt, needles spaced different and everything and they dont have the removable needle

Mark,

Joyce is on to something here. While just a Stihl, my 056 MagII has a semi-adjustable hi-speed circuit Tillotson. Check out the adjustment sticker on the cover. Why your carb's behavior has changed over the past year is anyone's guess.

Chris B.

Chris, maybe it has something to do with the fact that I never cut with less then a 28" bar on this in mostly big wood and it was pulling hard enough to clean its self out. The H needle has always set about 3/4 out which I thought was lean enough.

I know it was blubbering badly with a 20" in little wood.

 

[Wildman1024]

Mark,

Joyce is on to something here. While just a Stihl, my 056 MagII has a semi-adjustable hi-speed circuit Tillotson. Check out the adjustment sticker on the cover. Why your carb's behavior has changed over the past year is anyone's guess.

Chris B.

Now that seems crazy but maybe that's how the carb is supposed to be set o the 925. If need be just open it up a little to where you like it. Seems maybe 1/2 a turn out may not be to lean or the wring setting after all. Ceveryone thinks something is wrong but in reality nuttin is wrong and it's basically a fixed h carb that everyone wants to adjust like a normal carb

 

[roncoinc]

Yes please do! It might keep my hair from getting more grey. It might make some sense out of it! "

If you didnt work on dem pullon's you wount have so many grey hairs !

"Maybe you could scan it and post it here, but if not and you send it to me I will do that for the benift of the rest of the members. "

i would like a copy also.

"Yes you did but the older Poulan style 59A carbs are quite a bit differnt, needles spaced different and everything and they dont have the removable needle "

Was wondering if the carb was a bolt on replacement to see how it goes..
Just shave your head and dont wory about hair color it's over rated anyway..

 

[Modifiedmark]

If you didnt work on dem pullon's you wount have so many grey hairs !

Hey now watch it! LOL