Interesting diagnosis id like to share.

[RED-85-Z51]

Got stumped last week by a trimmer. I mostly never work on disposable stuff but..i got talked into working on an older Troy Bilt 2cycle trimmer...the ryobi style with the muffler on the bottom.

Simple enough...fuel lines leaking at the tank, put on new lines. Ran great..but flooded upon shut off. Okay...pulled the carb and put a kit in it...still ran great but still flooded. Ordered a new carb...put it on, ran perfect...but fuel dribbled out 5 seconds after shut down. I put on another gas cap...still flooded.

Any guesses on what fixed it.. And why?

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[keegantimber]

I'm not sure how the fuel system is configured. Sounds like the tank was pressuring? Excess heat causing fuel to expand pressuring tank? Heat tape applied to gas tank ?

 

[RED-85-Z51]

I'm not sure how the fuel system is configured. Sounds like the tank was pressuring? Excess heat causing fuel to expand pressuring tank? Heat tape applied to gas tank ?

That was the diagnosis i chased and tank pressure was partly to blame but was not the cause.

Its a basic system, line from tank to carb, then carb to primer and from primer to tank...fuel is drawn thru the carb and returned to the tank by the primer

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[Ikeholt]

Glad you got it fixed. Next step for me would be flinging it across the parking lot.

 

[RED-85-Z51]

The issue was....the primer bulb. The tank, like any other tank..built a very light pressure when warmed up but it was not enough to blow the inlet needle off its seat. The primer was letting pressure back thru the return side of the carb. New primer...problem solved. The real kicker was he had put on the new primer recently so it was new...but defective

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[keegantimber]

Interesting thanks

 

[Cliff R]

Glad you got it fixed. Next step for me would be flinging it across the parking lot.

That's what I do with the "low end" stuff folks drag up to the shop, or at least that's what I want to do with it. Poulan plastic box-store saws top the list, followed closely by the "re-badged" Poulan/Husqvarna saws they marketed for a while. I absolutely HATE some of the fuel line set-ups they used on the bottom of the barrel stuff and can't stand any sort of leaks or "seeping" where they go thru the plastic tanks.

I'm with you on the "almost never" working on those sort of things as there are lessons in humility just waiting for you, typically with diminishing returns for your time spent pissing around with them. Even with over 20 years at this deal full time I still learn some HARD lessons as I just think I can fix anything, no matter how big of a POS it is.

Glad you got that one figured out........Cliff

 

[MacAttack]

Thanks for sharing this, I've found the cheaper string trimmers can be the biggest pain in the a$$ to make them run right. I have 2 freebie Weedeater Featherlites that I want to sell, I think they both need carb diaphragms. The one will start and run with NO choke, and NO priming, if I apply either it instantly floods. But then after it's running for a bit, it starts to run like garbage. I did throw it once... but onto a pile of branches so that I didn't break it, haha.