Weeeater Poulan XT20 T...help!!

[rbstern]

One more thing. I just figured out how to get a close up of your carb pic. I think that fuel bulb is missing lines!

The fuel bulb is normally plumbed inline with the fuel tank pickup line. The plumbing looks like this:

Fuel pickup in tank --> Primer bulb input barb --> Primer bulb ---> primer bulb output barb --> carb fuel inlet --> carb excess fuel outlet --> tank return line

When you push and release the bulb, it creates a vacuum in the line to the fuel pickup in the tank, which sucks the fuel into the bulb and forces it down to the carb fuel intake. There's a fixture in the carb that allows fuel to be siphoned off by the venturi created by the carb's air intake. Additional fuel under excess pressure from the bulb flows back to the tank via a return line.

 

[canucklehead]

I worked on one of those Inteks for my brother. It had a goofy electronic fuel solenoid on carb. Replaced it, it ran better but never seemed right. May have been complete carb with the solenoid attached to it. It still runs if you feather throttle just right, but doesn't seem right. It seems to lope or surge a bit.

I never adjusted the H&L screws and assume they were pre-set at factory. They also use a specialty screw with a splined shaft and I don't have the screwdriver.

I start it choked and it runs. It won't stay running choked or un-choked. I believe I take off choke then rev it. It goes 3-5 seconds and just dies. No cough or sputter...like you hit a kill switch. If I leave it to idle on choke, or no choke, same thing. I think it dies quicker on choke, but it's so short either way, tough to tell. I just spoke with local shop, they told me to look through plug hole to cylinder walls and if scratch marks visible, that would be my issue. Said it could also be coil. Most coil problems I've had are no start at all.

 

[canucklehead]

yes, I'm not seeing any fuel lines from bulb but i do see those little barbed spigots. Which side is suck and which side is blow on the primer bulb? I never removed any lines from it. Also, on this model the parts diagrams don't show any fuel lines from the primer bulb to the carb or tank, but they do show fuel lines from tank to carb.

 

[rbstern]

I worked on one of those Inteks for my brother. It had a goofy electronic fuel solenoid on carb. Replaced it, it ran better but never seemed right. May have been complete carb with the solenoid attached to it. It still runs if you feather throttle just right, but doesn't seem right. It seems to lope or surge a bit.

Yep. Got that little dooflickey with the electrical lead on the carb. Needlessly fussy. Also a killer of batteries, if you leave the switch in the run position.

I never adjusted the H&L screws and assume they were pre-set at factory. They also use a specialty screw with a splined shaft and I don't have the screwdriver.

I start it choked and it runs. It won't stay running choked or un-choked. I believe I take off choke then rev it. It goes 3-5 seconds and just dies. No cough or sputter...like you hit a kill switch. If I leave it to idle on choke, or no choke, same thing. I think it dies quicker on choke, but it's so short either way, tough to tell. I just spoke with local shop, they told me to look through plug hole to cylinder walls and if scratch marks visible, that would be my issue. Said it could also be coil. Most coil problems I've had are no start at all.

The problem may be something else, but I think you've got to adjust the idle screws to further diagnose what you are dealing with.

 

[rbstern]

yes, I'm not seeing any fuel lines from bulb but i do see those little barbed spigots. Which side is suck and which side is blow on the primer bulb? I never removed any lines from it. Also, on this model the parts diagrams don't show any fuel lines from the primer bulb to the carb or tank, but they do show fuel lines from tank to carb.

Don't remember which is which, but it's easy enough to figure out: Put your thumb over one of the outlets, press the bulb. If you get suction when you release the bulb, that's the fuel tank side.

I don't know enough about these machines to say how well they work with the bulb plumbed out of the system. It's entirely possible that by not having it plubmed, you're getting more fuel to the carb and creating a rich condition, even at factory mixture screw settings, simply due to less fuel lines, and the volume of the bulb being eliminated (less work for the engine to move more fuel through the shorter lines).

 

[canucklehead]

upon close inspection, the primer bulb assembly spigots are actually labelled "tank and carb". I also tried to feel for suck and blow but very hard to distinguish. glad it was labelled.

After setting that up right, no change. So i went and bought a new NGK BM4A plug. Not sure of the gap so i left it as-is out of the box. Wow, it will actually run now. I ran it for 15 minutes. BUT.... it will only run on 3/4 choked, and seems to rev okay, but not screaming the way it should. Full choke it dies, half choke it dies. I am taking it to my expert friend to tune the H &L. Need a special tool to turn those spline head screws.

 

[kebo]

Just a weird thought, since I don't know much about these small 2 strokers, but is it possible that it's just losing the spark after a few seconds? If the plug is wet, that would seem to indicate it was getting fuel, right? We all know that it takes three things for that motor to run and it just seems like it has air and fuel, and I would say you've pretty much eliminated everything in the fuel path, which would leave you with it not getting enough spark for the combustion. Good luck!

 

[canucklehead]

Yes, your theory is definitely a possibility. In fact, I spoke with our local repair shop and they said cylinder could be scored and when cold, it will start and run a bit, but as soon as it heats up a bit it would die (I assume it loses compression from the heat/expansion?).

The other thing they mentioned was as you suggest: coil is wonky so sometimes it sparks and sometimes it doesn't, or not sparking properly, etc....

This is the final outcome: Yesterday after it ran for 15-20 minutes with new plug on 3/4 choke, I figured I was getting close. WOO-HOO!! I took it to my 2-stroke specialist buddy today. He tweaked the H & L screws with special splined carb adjustment tool, and now it runs as good as it can possibly run. I think he said L screw was factory set at 1.5 turns and he tweaked it to 2 turns. He also tweaked H a bit and it is running strong for the time being.

FWIW I still think it's a POS and it was a complete waste of time and money to work on this. (***sigh** dam that OCD!!). Same friend told me any curved shaft Weedeater, Poulan, Ryobi, etc.... is a bic lighter when it won't run. Stihl, Echo older Husqvarna worth trying to fix. AND... I would recommend ALWAYS start by checking compression before you start chasing parts and throwing away money like I did.