Stihl 661 mtronic not pulling fuel

[joe25DA]

And this is AFTER the mtronic service kit. Runs off a prime then dies. Must be missing something

 

[cscltd]

If it ran ok before doing kit, then I would suspect that something was not put back correctly??

 

[joe25DA]

Nope did not, it ran after I did the kit. I drained the fuel and she sat for about 9 months. Don’t use a 30” saw often around here.

 

[cscltd]

Drained and ran dry?
pull carb and check diaphragms. Fuel line

 

[joe25DA]

Doubtful, not impossible. The carb was kitted, and I’ve had saws sit for years dry and draw fuel. I think this might be an electronic problem

 

[Kodiak Kid]

Doubtful, not impossible. The carb was kitted, and I’ve had saws sit for years dry and draw fuel. I think this might be an electronic problem

Did you conduct the throttle sequence that's required when new?

 

[Kodiak Kid]

Nope did not, it ran after I did the kit. I drained the fuel and she sat for about 9 months. Don’t use a 30” saw often around here.

If I have a power saw that's going to sit fir a bit. I'll STIHL fire them up to clear the carb jets of old gas. I do this about every two or three weeks.

 

[cdherman]

Doubtful, not impossible. The carb was kitted, and I’ve had saws sit for years dry and draw fuel. I think this might be an electronic problem

Ain't electronics if it runs for a while after being primed, then dies. Its either something in the fuel pump diaphragms of the carb, or the impulse setup (does 661 have the painful Stihl impulse line?) or the crank seals are perhaps dry and allowing air to get into the crank and ruining your vacuum impulse.

If it starts with the primer bulb, then its not getting ongoing fuel for some reason.

 

[Kodiak Kid]

Ain't electronics if it runs for a while after being primed, then dies. Its either something in the fuel pump diaphragms of the carb, or the impulse setup (does 661 have the painful Stihl impulse line?) or the crank seals are perhaps dry and allowing air to get into the crank and ruining your vacuum impulse.

If it starts with the primer bulb, then its not getting ongoing fuel for some reason.

Do some 661's have primer bulbs? I have a 661M-tronic, as well as a manual 661. Neither have a primary bulb.

 

[ballisticdoughnut]

Do some 661's have primer bulbs? I have a 661M-tronic and as well as a manual 661. Neither have a primary bulb.

They never had purge bulbs.

 

[Kodiak Kid]

They never had purge bulbs.

I didn't think so.

 

[cscltd]

It is possible that it could be wiring harness, but they usually give intermittent firing usually under load.

 

[stihltech]

It is just a carburetor. Take it apart and check for corrosion and contamination. Stiff metering diaphragm, sticking flap valves on pump side. Inlet valve and lever free. Pulse passage open an motor also. High speed nozzle check valve sticking. All the est of the fuel system also.
Seen a lot of pulse hoses pulled off.

 

[joe25DA]

Did you conduct the throttle sequence that's required when new?

I know I didn’t cut with it. I have seen the sequence since then, rev, idle and shut off. No I didn’t then

 

[joe25DA]

Ain't electronics if it runs for a while after being primed, then dies. Its either something in the fuel pump diaphragms of the carb, or the impulse setup (does 661 have the painful Stihl impulse line?) or the crank seals are perhaps dry and allowing air to get into the crank and ruining your vacuum impulse.

If it starts with the primer bulb, then it’s not getting ongoing fuel for some reason.

No start. Ran off prime. I’ll be pulling that carb off

 

[sean donato]

It is just a carburetor. Take it apart and check for corrosion and contamination. Stiff metering diaphragm, sticking flap valves on pump side. Inlet valve and lever free. Pulse passage open an motor also. High speed nozzle check valve sticking. All the est of the fuel system also.
Seen a lot of pulse hoses pulled off.

This right here is good advice. The carb is still a basic carb with the fuel solenoid on it. Holes in fuel lines, air leaks, clogged fuel pump ect all still apply.

 

[joe25DA]

found the problem when I was putting the saw in my truck and fuel was dripping out…That was new Stihl fuel line that split. It’s still soft, never had that happen before. It’s only been on there 8 months. Easy fix saw runs awesome and now it’s with its new owner.

 

[sean donato]

Always love when it's something simple.