TroyBilt Primer Bulb Problem

[R4665]

Troy-Bilt String Trimmer Model TB22EC

Helping my son with his string trimmer. Problem: when the primer bulb is pressed, it stays depressed. Fuel seems to be getting "sucked" from the tank to the carb, but fuel is not flowing through the carb back to the tank.

What I've had him do so far:
1. Removed carb and disassembled. There was some dirt on the screen. I had him spray carb fluid in all of the holes on both sides of the carb. I did not have him remove the needle, but had him spray some carb fluid around the needle with it pressed open. Fluid flowed they the screen on the other side.
2. Sprayed carb fluid on both sides of the part the primer bulb attaches to.
3. Had him blow air through the fuel line the pickup is attached to. He was able to "blow bubbles" in the gas tank which would indicate that the fuel line is clear. Also had him blow air thru the return fuel line. It is clear.
4. When no fuel lines are attached, the primer bulb presses and releases like it should. The problem only occurs when the fuel lines are attached.

Ideas? Suggestions as what to do next?

Thanks. Robert

[bgsengine]

Troy-Bilt String Trimmer Model TB22EC

Helping my son with his string trimmer. Problem: when the primer bulb is pressed, it stays depressed. Fuel seems to be getting "sucked" from the tank to the carb, but fuel is not flowing through the carb back to the tank.

What I've had him do so far:
1. Removed carb and disassembled. There was some dirt on the screen. I had him spray carb fluid in all of the holes on both sides of the carb. I did not have him remove the needle, but had him spray some carb fluid around the needle with it pressed open. Fluid flowed they the screen on the other side.
2. Sprayed carb fluid on both sides of the part the primer bulb attaches to.
3. Had him blow air through the fuel line the pickup is attached to. He was able to "blow bubbles" in the gas tank which would indicate that the fuel line is clear. Also had him blow air thru the return fuel line. It is clear.
4. When no fuel lines are attached, the primer bulb presses and releases like it should. The problem only occurs when the fuel lines are attached.

Ideas? Suggestions as what to do next?

Thanks. Robert

Replace the fuel filter.

They clog up easily even if you can seem to blow air through them.

[KE4AVB]

Very good chance that primer base is plugged. WIth this carburetor being around 20 usd I would just replace it instead spending to much time and money on doing an R&R on it. Ultrasonic cleaner can unplug these usually but it take a few cycles as once they are plugged with old fuel thewy are nearly impossible to get working again.

[bgsengine]

Very good chance that primer base is plugged. WIth this carburetor being around 20 usd I would just replace it instead spending to much time and money on doing an R&R on it. Ultrasonic cleaner can unplug these usually but it take a few cycles as once they are plugged with old fuel thewy are nearly impossible to get working again.

Was my first thought, BUT.. then he writes:

4. When no fuel lines are attached, the primer bulb presses and releases like it should. The problem only occurs when the fuel lines are attached

[KE4AVB]

I miss that I was in hurry as two customers show when I was posting. They brought the 21HP rebuilt engine I had.

I would also suspect a bad tank filter or a pinched line first. I try it without the fuel filter on the line and see what happens.

[R4665]

I would also suspect a bad tank filter or a pinched line first. I try it without the fuel filter on the line and see what happens.

Replace the fuel filter. They clog up easily even if you can seem to blow air through them.

Thanks for the suggestions. I will have him remove the fuel filter and see what happens.