Weeeater Poulan XT20 T...help!!

[canucklehead]

I've been messing with my father in laws Weedeater/Poulan XT20 T weedeater. Unfortunately, I'm cursed with being somewhat handy and don't mind cleaning carbs, or monkeying a bit. I knew the moment this treasure arrived that I should have junk-piled it.

It will start, run for about 10 seconds, then die. Does this over and over. It's like it starves for fuel. Hard to start, then if I leave it, it starts easy, but dies the same way after 10 seconds or so.

First I cleaned carb with ultrasonic cleaner. No real change.Since then I've: replaced with new carb, new carb mounting gasket, new air filter, fuel filter, new fuel lines, tried to clean out exhaust pipe (brake cleaner and compressed air), AND it still runs like crap. . I have not checked compression. The fact it starts and seems to run, rev, but then die....??

I noticed it had a Champion RJ8 plug. I tried a new Champion CJ8 I had. According to web, the Poulan plug is no longer available and they only give a Poulan part number. The web says it uses a CJ14 plug, or NGK BM4A. Is a new plug going to fix these issues?

Whiskey Tango Foxtrot??

It is now an OCD overload that I have to see run properly. And I've thrown about $50 in parts at it so the obsession is only getting worse. Thanks for any help you can offer.

 

[eddie48]

I've been messing with my father in laws Weedeater/Poulan XT20 T weedeater. Unfortunately, I'm cursed with being somewhat handy and don't mind cleaning carbs, or monkeying a bit. I knew the moment this treasure arrived that I should have junk-piled it.

It will start, run for about 10 seconds, then die. Does this over and over. It's like it starves for fuel. Hard to start, then if I leave it, it starts easy, but dies the same way after 10 seconds or so.

First I cleaned carb with ultrasonic cleaner. No real change.Since then I've: replaced with new carb, new carb mounting gasket, new air filter, fuel filter, new fuel lines, tried to clean out exhaust pipe (brake cleaner and compressed air), AND it still runs like crap. . I have not checked compression. The fact it starts and seems to run, rev, but then die....??

I noticed it had a Champion RJ8 plug. I tried a new Champion CJ8 I had. According to web, the Poulan plug is no longer available and they only give a Poulan part number. The web says it uses a CJ14 plug, or NGK BM4A. Is a new plug going to fix these issues?

Whiskey Tango Foxtrot??

It is now an OCD overload that I have to see run properly. And I've thrown about $50 in parts at it so the obsession is only getting worse. Thanks for any help you can offer.

re: spark plug - CJ8 plugs don't seem to work well anymore with the new gasolines. CJ14 should be ok.
re: starving for fuel - sounds like that could be it. Is the tank vent/gas cap clear to allow air to enter?
If it starts and runs but then dies after a few seconds of high speed operation, I would also look at the height of the metering lever and try opening the high speed jet screw a quarter turn at a time.

 

[MoKelly]

I think the gas cap comment could be the issue. I had a weedeater blower that acted exactly like your trimmer. As it was dying, if I unscrewed the cap the machine came back to life. Easy check.

Good luck.

MoKelly

 

[canucklehead]

I wondered about venting too. I did notice gas drip out the cap when I had it turned upside down. I will try that again though.

MoKelly, I assumed they pre-set new carb at factory, including high idle jet and metering. The H & L screws have a splined top, so I need some sort of special splined screwdriver to tweak.

 

[canucklehead]

well I played some more. I think it vents fine as fuel drips out cap when upside down. It is a little charcoal filter with a rubber plug on it. I pulled plug off, pulled cap off... no difference.

So out came the compression tester. 95 PSI. I added a couple drips of oil and got 110-115 PSI. Is 95 too low to run proper on these?

 

[rbstern]

PSI sounds ok to me. It should run at 95psi.

Did you replace the fuel bulb? On every Weedeater and Ryobi 2 stroke I've owned, the fuel bulb eventually cracked and needed to be replaced. I imagine modern gasoline with the ethanol blend speeds up that process. If there is a pinhole or crack forming in the bulb, it will allow air into the fuel line and cause a lean condition, starving the motor for fuel.

 

[canucklehead]

this is a strange primer bulb as it's part of the plate that covers carb, and then air filter assembly screws onto the plate. There are no fuel lines on this plate or the primer bulb. the primer bulb must somehow push air to create vacuum to suck fuel (??). Here is a pic.

I thought 2 strokes are typically around 120 PSI, and 90 PSI is too low. My brother brought over his Echo GT2000 curved shaft weedeater and it won't run. This time I first checked compression. After 4 pulls it reaches 140 PSI.

 

[rbstern]

Two different models from two different manufacturers won't necessarily have the same compression. Even so, 95psi dry, and 115psi wet, while a bit low, is in the ballpark. It's certainly high enough for it to run. That fuel bulb's plumbing can't be open to the atmosphere, because it wouldn't create any air pressure. Gotta be air leaking in somewhere, causing it to go lean. Are you choking to start it? Will it keep running with the choke part way on?

If you can't track down the leak, don't pour good money after bad. That machine isn't worth the cost of a motor rebuild.

 

[canucklehead]

thanks rbstern,

I thought primer bulb's main purpose was to make cold start easier. But i see what you're saying...if it leaks and allows air in, won't run right.

I've tried priming by adding fuel through spark plug hole and it seems to just die after a few seconds. Same if I leave it choked. Spark plug is wet.

Would plug be the cause?? I have a new CJ8 plug which isn't the recommended plug.

you are way too right on your comment about don't waste time/money on this.... It's become an obsession. I've spent $40-50 on parts (carb, fuel lines, gasket, air filter). It's hard to walk away.... I keep hoping that now it's something cheap and easy.

 

[rbstern]

I understand the obsession issue. I am right there with a 8 year old Briggs Intek 18.5 that quit, and not quite sure where to go next with it (if go with it at all).

It's possible the plug is being extinguished by fuel/oil mixture. If so, it's rich, not lean, and that should be easier to solve. That could be compounded if the plug you have runs cooler than whatever the stock plug is. Not a great idea to troubleshoot without the recommend plug. Hard to understand what variable you might be introducing.

Have you tried adjusting the mixture screws? I remember working on a neighbor's model of that same Weedeater, and IIRC, the carb has both high and low idle screws. Is it dying at idle, or with throttle applied? You could try adjusting the appropriate mixture screw up or down to see if the performance changes. I assume, since its a new carb, you have them set at or close to the recommend number of turns? Have you adjusted to see if richer or leaner makes a difference?

 

[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.