Any of you boys ever work on a Stihl TS760 ?

[ZeroJunk]

I spent too much time on one this morning. Just would not take the fuel. Funny thing is you could see it coming in the main nozzle and then just stop.
It is basically an 076 conversion. I had worked on one before that came from cutting steel at the world trade center post 9-11 . That one just had a piece of channel attached.
This one is different. So, I rebuilt the carb, replaced the top fuel line, impulse line. Pressure tested the bottom in tank hose. Same thing.

Well, as a last resort I looked at the IPL. What they did on this creation is convert the front oil tank to a separate fuel tank with it's own line and filter.

I have decided that it is pulling air in that front fuel line.

Question is , how do you get in there. The front what would be oil cap appears to be a glued in plug.
The second fuel line going from the top of the rear tank has a sheath around it and then disappears above where the impulse nipple comes out and enters the repurposed front tank.

So, how do you get in there? Or, is there a tech bulletin on replacing that front oil fill hole plug ?

Beats me. I suppose I could just block that whole mess that goes to the front.

I don't even understand how the fuel gets up there.

Bare with me . I am not particularly Bright.

 

[ZeroJunk]

I have been on this forum for a while. You have to wonder what happened to it.

On the bright side, I will figure this all out some time tomorrow. And, it may be of some value to somebody down the road.

 

[Chevboy0167]

It should be like the TS510 I reworked last summer.... maybe???

That front CAP is removable and is just snapped on there. Then Stihl used a plastic female hex plug for the tank cap that can be removed using a bolt with the correct hex.

 

[Chevboy0167]

https://www.ebay.com/itm/2325240694...044&customid=4c60a737ba0a1f39d073c01c421ec1e8

 

[ZeroJunk]

Thanks, that is the part of the puzzle that I was struggling with.

 

[Chevboy0167]

Yeppers. Took me a bit struggling too!

 

[ZeroJunk]

I hate to say it, but this thing may beat me.

The machine will run for a few seconds and you can see a strong stream of fuel coming out of the main nozzle. Then it just dries up.

Withe the advice of Chevboy I have replaced every fuel and impulse line. Both filters. And ,rebuilt the carb.

Does the same.

Now, I tried to blow through the impulse line by mouth , and it seemed to be clogged. Squirted some carb cleaner through it and it cleared up. Ran for a few seconds and quit. Same. You could see the fuel decrease and stop from the main nozzle.

So, is there or can there be enough gunk in the crankcase to clog that impulse line back up ?
Could there be a crack in the nipple where the lines attach to the sump line in the tank ?
Something stopped up in the carb ?

This is the Tillotson that has three nipples. One for impulse, one for fuel, and another that vents off of the metering diaphragm back in to the intake.

Appears to be nothing like it still available.

It galls me to give up on anything. But, this thing might get me.

 

[pioneerguy600]

alexcagle is sort of an expert on the cutoff saws, lets see if he is around,@alexcagle

 

[Chevboy0167]

To me it sounds like the tank elbow fitting is venting air into the fuel supply side maybe??? Stihl calls it tank vent.

 

[cookies]

I hate to say it, but this thing may beat me.

The machine will run for a few seconds and you can see a strong stream of fuel coming out of the main nozzle. Then it just dries up.

Withe the advice of Chevboy I have replaced every fuel and impulse line. Both filters. And ,rebuilt the carb.

Does the same.

Now, I tried to blow through the impulse line by mouth , and it seemed to be clogged. Squirted some carb cleaner through it and it cleared up. Ran for a few seconds and quit. Same. You could see the fuel decrease and stop from the main nozzle.

So, is there or can there be enough gunk in the crankcase to clog that impulse line back up ?
Could there be a crack in the nipple where the lines attach to the sump line in the tank ?
Something stopped up in the carb ?

This is the Tillotson that has three nipples. One for impulse, one for fuel, and another that vents off of the metering diaphragm back in to the intake.

Appears to be nothing like it still available.

It galls me to give up on anything. But, this thing might get me.

sounds like you should pull the cylinder and rinse out the crank case to check for loose rubber bits, pebbles, gasket material etc

 

[ZeroJunk]

To me it sounds like the tank elbow fitting is venting air into the fuel supply side maybe??? Stihl calls it tank vent.

View attachment 1217402


View attachment 1217403

There are three parts to that contraption. I think 33,34,35 on the IPL.

The line that tees off in the tank has an insert, and a grub screw. And goes in the side of the fat part of the in tank fuel line that the part in your photo pushes in to.

If it is sucking air that would do it. I don't see any cracks. But, those little nipples are there for some reason.

I don't exactly understand how it functions.

 

[ZeroJunk]

To me it sounds like the tank elbow fitting is venting air into the fuel supply side maybe??? Stihl calls it tank vent.

View attachment 1217402


View attachment 1217403

It will be next week probably. But, since the fill cap is on top I will take a filter and a piece of fuel line and just drop it straight in the tank through the fill cap. If it runs that way we will know it's leaking there somehow.

 

[ZeroJunk]

OK. I took a piece of Tygon and stuck a filter on it, put it on the carb inlet, stuck it in the fuel tank fill opening, and the saw runs fine.

So, I ordered the tank vent fitting and the in tank hose.

See if they have them somewhere.

I still don't know how that tank vent is supposed to work.

 

[Chevboy0167]

I'll have to look for the old one I replaced and see if I can destruct it. I know I kept it but now I gotta find it!

 

[ZeroJunk]

I'll have to look for the old one I replaced and see if I can destruct it. I know I kept it but now I gotta find it!

Well, if you look at the IPL for the TS-760 there are two versions.

This one the tank vent with the insert and grub screw are actually inside the tank. Then you have the two nipples on the other side of the plastic assembly that go to the front and back tank.

First off, the front tank vent dumps right in to the metal air filter holder internal to the air filter. Why do you even need another ? And, how does the main tank vent vent inside the tank ?

Beats me.

 

[stihltech]

What happens when you cut metal- sparks.
What happens when you get fuel fumes near sparks-fire.
Hence the need for the fancy venting.
When they do burn (especial the old TS08 and TS350, makes a mess and gets exciting fast.
Fix the vent correctly.
Oh and if you say you only cut concrete, I hope there is no rebar in it. Concrete, asphalt, etc will plug and open vent.

 

[ZeroJunk]

What happens when you cut metal- sparks.
What happens when you get fuel fumes near sparks-fire.
Hence the need for the fancy venting.
When they do burn (especial the old TS08 and TS350, makes a mess and gets exciting fast.
Fix the vent correctly.
Oh and if you say you only cut concrete, I hope there is no rebar in it. Concrete, asphalt, etc will plug and open vent.

I hear you clucking, but I can't find your nest.

 

[ZeroJunk]

Really. You either understand the physics behind how that in tank tank vent is supposed to work. Or, babble some platitudes . Take your pick.

 

[stihltech]

Just what I see in the shop. No platitudes. Just saw repair.

 

[stihltech]

Maybe this will help