Hello folks. I have a 5 yr old, gently used Stihl line trimmer. This one comes pretty close to being the model I own.
It seems like it has been pretty temperamental towards starting and staying running, but I can usually get the job done by tweaking the choke and playing with the throttle. However today it has become pretty much unusable. I put the trimmer on the start throttle setting with the hand control. Then I full choke it. It starts up on about the second pull. After playing with the throttle and barely moving the choke a bit (from full choke) I can get it to run fast and it sounds good.
But in spite of it being totally warmed up it still requires what appears to be 95% choke on the knob.
Full choke:
Optimal choke after full warmup:
You can hardly tell I have moved the knob but this subtle difference makes the thing run well. Moving to full open or even a bit more open kills the engine at any throttle setting.
You might think "Just leave the knob in the mostly choked position". However, since the knob is so close to the closed position, it snaps to full closed if I let it go, thus I need one hand on the choke to keep it running well and that's not practical. I have taken the thing apart as far as I dare. I removed the plastic piece that houses the air filter. I suctioned, with a syringe, fuel through the fuel intake line and it free flows. The pump bulb needs replacement (has a small crack) but once primed that should not (I guess) present a problem.
I even ditched the old oil / petrol mixture in the tank and put in new fuel / oil, but no difference. What could cause the need for a 95% choke? Could the damaged primer bulb be causing an air leak and starving the fuel flow? Perhaps the added choke adds extra suction and overcomes the air leak in the bulb (I'm just now thinking this through. It does lift the fuel through suction and the damaged pump bulb might be reducing it. I'll order a new bulb).
Any thoughts?
Thanks for reading!!!
It seems like it has been pretty temperamental towards starting and staying running, but I can usually get the job done by tweaking the choke and playing with the throttle. However today it has become pretty much unusable. I put the trimmer on the start throttle setting with the hand control. Then I full choke it. It starts up on about the second pull. After playing with the throttle and barely moving the choke a bit (from full choke) I can get it to run fast and it sounds good.
But in spite of it being totally warmed up it still requires what appears to be 95% choke on the knob.
Full choke:
Optimal choke after full warmup:
You can hardly tell I have moved the knob but this subtle difference makes the thing run well. Moving to full open or even a bit more open kills the engine at any throttle setting.
You might think "Just leave the knob in the mostly choked position". However, since the knob is so close to the closed position, it snaps to full closed if I let it go, thus I need one hand on the choke to keep it running well and that's not practical. I have taken the thing apart as far as I dare. I removed the plastic piece that houses the air filter. I suctioned, with a syringe, fuel through the fuel intake line and it free flows. The pump bulb needs replacement (has a small crack) but once primed that should not (I guess) present a problem.
I even ditched the old oil / petrol mixture in the tank and put in new fuel / oil, but no difference. What could cause the need for a 95% choke? Could the damaged primer bulb be causing an air leak and starving the fuel flow? Perhaps the added choke adds extra suction and overcomes the air leak in the bulb (I'm just now thinking this through. It does lift the fuel through suction and the damaged pump bulb might be reducing it. I'll order a new bulb).
Any thoughts?
Thanks for reading!!!
