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TroyBilt TB22EC String Trimmer - No Start

#1

R

RVII

I have a string trimmer that had been sitting for a long time, and I thought I would try to get it running. I did the usual: cleaned the fuel tank, replace the fuel lines and filter, replace the carburetor, and fill with fresh gas/oil mix, but still no good. I pulled the engine to look at the piston, and sure enough, the cylinder was pretty scored up. I replaced the short block with a new assembly. The new assembly came with a new spark plug and coil pack. I set the coil spacing with my brass feeler gauge. I verified spark was good at the plug, and the compression built up to about 120 PSI, after 4 or 5 pulls on the recoil rope. Oh, I also verified that my primer bulb circuit was flowing a nice stream of return fuel to the tank. After all this, I am still unable to get this trimmer started. I started with the customary 1 1/2 turns out from seated on the low and high speed jets, but still no signs of life. So, I have spark. I have fuel. I have compression. And . . . the fuel mix that I am using works in my Echo leaf blower. Any thoughts on this?
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#2

StarTech

StarTech

Have you tried to see if it will even hit with a little fuel added directly to the cylinder? Might be a flywheel to coil timing issue.


#3

R

RVII

I have not (yet). I will try that, once everyone finally wakes up. My new short block came with the flywheel already installed. I can't imagine it would be out of time, but who knows these days . . .

What are your thoughts on the premixed cans of fuel/oil?

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#4

StarTech

StarTech

Never tried them but I am cheap and mix my own shop fuel mix here. I was out yesterday cleaning one of my customer's Dingos with it.

I let others voice their opinions on it as I kinda see it as marketing scheme myself, just for very lazy people but that is just my opinion.


#5

R

RVII

Understood. I will try my current mix, directly into the cylinder and see if it wants to start. More to come . . .


#6

R

RVII

StarTech said:
Never tried them but I am cheap and mix my own shop fuel mix here. I was out yesterday cleaning one of my customer's Dingos with it.

I let others voice their opinions on it as I kinda see it as marketing scheme myself, just for very lazy people but that is just my opinion.
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I tried putting my 2-cycle gas mix directly into the cylinder, but had no luck getting the thing to fire off. I double checked my spark and checked my spark plug gap. All good.

Below are some images of the short block I removed. I compared the location of the piston in its stroke to the feel of the permanent magnet passing the coil, and both the new engine and the old engine seem to be showing the same resistance, in the same cycle position, when the permanent magnet passes the coil. I am at a loss . . .

1673188784070.png


#7

R

RVII

RVII said:
I tried putting my 2-cycle gas mix directly into the cylinder, but had no luck getting the thing to fire off. I double checked my spark and checked my spark plug gap. All good.

Below are some images of the short block I removed. I compared the location of the piston in its stroke to the feel of the permanent magnet passing the coil, and both the new engine and the old engine seem to be showing the same resistance, in the same cycle position, when the permanent magnet passes the coil. I am at a loss . . .

View attachment 63163
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Other than sealing out debris from the crankcase, does the rear cover o-ring (#4) provide any sealing properties that require a tight seal? Fuel delivery is created by the downward stroke of the piston, correct?
1673190059482.png


#8

StarTech

StarTech

This is a two cycle engine and crankcase is part of the intake system so yes that cover requires a tight seal.

With fuel directly introduced it should had hit if the timing is correct even with the crankcase partially unsealed.

I'm not there to look for myself but something is definitely not right.


#9

T

Tbone0106

RVII said:
I have not (yet). I will try that, once everyone finally wakes up. My new short block came with the flywheel already installed. I can't imagine it would be out of time, but who knows these days . . .

What are your thoughts on the premixed cans of fuel/oil?

View attachment 63162
Click to expand...
I use this stuff, but not all the time. I like to run regular pump gas through most of the season, when I'm using the machines regularly. Then I switch to this stuff around the first of September. The ethanol in the pump gas will do bad things while everything sits over the winter, so I wean my 2-strokes onto the canned fuel before the snow flies. That way, they're ready to go in the spring. (My little snow-thrower is an exception; I use the canned stuff exclusively in that.)

Where I live, the nearest non-ethanol gas is 35-40 miles away, out on a marina fuel dock. The canned stuff is pretty pricey, but so is driving my truck 80 miles to fetch pure gas (at a premium price).


#10

R

RVII

Tbone0106 said:
I use this stuff, but not all the time. I like to run regular pump gas through most of the season, when I'm using the machines regularly. Then I switch to this stuff around the first of September. The ethanol in the pump gas will do bad things while everything sits over the winter, so I wean my 2-strokes onto the canned fuel before the snow flies. That way, they're ready to go in the spring. (My little snow-thrower is an exception; I use the canned stuff exclusively in that.)

Where I live, the nearest non-ethanol gas is 35-40 miles away, out on a marina fuel dock. The canned stuff is pretty pricey, but so is driving my truck 80 miles to fetch pure gas (at a premium price).
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Good to know. I am still getting my butt kicked by this trimmer. New engine, new carb, new coil, new spark plug, new fuel lines and filter - No start . . . Frustrating, to say the least. Replacing the carburetor insulator and o-ring style gaskets on this part and the rear crankcase cover next. It's got to be something simple . . . I have compression, fuel, and spark.


#11

T

Tbone0106

RVII said:
Good to know. I am still getting my butt kicked by this trimmer. New engine, new carb, new coil, new spark plug, new fuel lines and filter - No start . . . Frustrating, to say the least. Replacing the carburetor insulator and o-ring style gaskets on this part and the rear crankcase cover next. It's got to be something simple . . . I have compression, fuel, and spark.
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A few thoughts.....

First, I've seen instances where the fuel lines on these little carbs are hooked up backwards. Some folks don't understand that the primer bulb on these things is designed to gently draw fuel to the carb by suction. The discharge (pressure) line from the primer bulb should run directly to the fuel tank, and the suction line should go directly to the "high" side of the carb. Getting these lines mixed up could bypass the carb completely or even pump gas OUT of the carb. Yeah, it's an amateur's mistake, but we're all amateurs until we ain't.

Second, I've seen instances where the primer bulb was overused, and the carb literally floods. Hell, it hasn't been that long ago when NOTHING had a primer bulb on it! They're made mainly to save you a few pulls on the rope; that's all.

Third, you might try backing the mixture screws out a half turn or even a full turn from the "customary 1 1/2 turns." That setting may be customary, but it ain't carved in stone. Many is the time I couldn't get a burp out of a little engine at 1 1/2 turns, but found success (or at least some burping) at a richer setting.

Good luck!


#12

B

bertsmobile1

There is a right way to do this job and there is a wrong way
Doing it the wrong way and your butt will hurt.
So now in place of finding out what the problem was in the first place you have added 8 new potential sources of failure .
So IMHO put it all back together as it was in the first place then methodically work your way through to locate the problem first before you start throwing random parts at it .
And if they were cheap amazon/ebay parts then very good chance some if not all of them were faulty parts that the QC section rejected in the first place .
Or methodically work your way through the trimmer as it is
You start by pressure testing the fuel tank & vent
Then you pressure test the crankcase
then you pressure test the carb
Unless your cylinder compression tester is specically designed for small engines ( $$$$$ ) then your PSI figures are meaningless
IF you have fuel compression & spark then the engine will fire .
The lazy way is to shoot a VERY VERY VERY short shot of carb cleaner ( starting fluid if you have no CC ) down the plug hole & try to start
No bang = timing out, low compression, bad plug or blocked exhaust
If that works then it is another short shot down the carb
No bang = bad crankcase seals or blocked exhaust or piston installed backwards ( yes it happens )


#13

R

RVII

bertsmobile1 said:
There is a right way to do this job and there is a wrong way
Doing it the wrong way and your butt will hurt.
So now in place of finding out what the problem was in the first place you have added 8 new potential sources of failure .
So IMHO put it all back together as it was in the first place then methodically work your way through to locate the problem first before you start throwing random parts at it .
And if they were cheap amazon/ebay parts then very good chance some if not all of them were faulty parts that the QC section rejected in the first place .
Or methodically work your way through the trimmer as it is
You start by pressure testing the fuel tank & vent
Then you pressure test the crankcase
then you pressure test the carb
Unless your cylinder compression tester is specically designed for small engines ( $$$$$ ) then your PSI figures are meaningless
IF you have fuel compression & spark then the engine will fire .
The lazy way is to shoot a VERY VERY VERY short shot of carb cleaner ( starting fluid if you have no CC ) down the plug hole & try to start
No bang = timing out, low compression, bad plug or blocked exhaust
If that works then it is another short shot down the carb
No bang = bad crankcase seals or blocked exhaust or piston installed backwards ( yes it happens )
Click to expand...
I appreciate the candid reply. I should know better from working in the automotive industry. I have the original carburetor, and I can clean that out and re-use. The replacement carb is aftermarket. The engine and ignition module (coil) are MTD. I will retrace my steps and see if I can get the engine to attempt to fire, then follow your suggestions. What turned out to be a free weed trimmer from my Dad has turned out to cost me almost more than the tool is worth . . . lesson learned.


#14

B

bertsmobile1

Well I am from OZ where we have sensible gun laws so we speak our minds without the fear that the other party will whip out a fire arm and remove our minds from our bodies .
The down side of forums like this one is every body has their "pet problem" the one that caused them untold grief which they subconsciously project onto every one else without taking the time to read through the posts properly ( and I do it too ).
As all of the full time techs will tell you the most difficult part is the diagnosis .
We live in a time when just about every thing will tell you what is wrong , plug in the machine and read off the diagnosis
Having to do the whole thing from scratch is a lot harder & takes a lot more experiance to get down pat.

Small hand held engines are a bigger problem because they are so sensitive and the slightest of problem will have them inoperable.
It is quite weird that mowers are lazy engines and will run ( badly ) over a massive range of mal adjustments
Small hand helds are working to their limit so any mal adjustment and they are non starters .
So we go from one extreme to the other


#15

R

RVII

Well, it finally started, and I was able to adjust the aftermarket carburetor to maintain a respectable idle and provide crisp throttle response to full throttle. I replaced the intake insulator and o-rings, and the crankcase o-ring, and the machine started. It only took a few pulls on the cord, and the machine was off and running.

I appreciate all the input from the forum members. This was a costly lesson, but hey, I basically have a new trimmer now . . . Thank you all.


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