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Say fellas, I have a Weed Eater featherlite fl26 that won't start. I can prime and pull all day and not a pop or sputter at all from it. I have good fresh gas in the tank. A new plug that gives me a good, fat, blue spark. There is compression. Enough to blow my thumb off the plug hole. I tried starting fluid but nothing. What I'm wondering is.....could there be a timing problem like with lawn mowers where the flywheel key gets sheared off throwing it out of time. I've replaced many keys where the mower won't fire at all. Replacing the sheared key makes it start immediately. I've never had any experience with trimmers so I thought I would ask before tearing it apart. Gas is getting to the cylinder as the plug gets wet. Trying to start according to the directions on the engine does no good. Gas is moving through the hoses when I prime. It used to start OK until last week. I used it, shut if off and a week later no start. The three basics.... compression, spark and gas but no start. Any thoughts on this problem?. Thank you.

Timing or blocked exhaust.
Try removing the muffler.

Bad news is most micro engines cast the key into the fly wheel so it is generally a new fly wheel.

You need to get a true compression test. blowing the finger off the spark plug hole may not be enough compression for it to run. Poulan says 90 psi is the minimum for combustion. And second checking for a clogged muffler. Have seen more than one dirt dauber plug mufflers, as we as some will have a screen that can be removed and cleaned. Gets clogged with carbon. Some of the newer models have the screen internal, and cannot be cleaned. Just have to replace the muffler.

A easy and fast test is to remove the muffler and see if it will start and run.

Thanks fellas for your replies. Looks like I'm going to have to tear it down. I don't have a compression tester so I'll have to find someone that has one and check that out. No keys for the flywheel? I was hoping that might be the problem. Clogged muffler. I will definitely check that out. It just seems strange that it ran very well for my last cut and a week later...nothing. Thanks again for your help. Got some work to do on the machine.

Check and/or disconnect the kill switch and give it a try.

The Ryobi used a tapered flywheel hole with a cast in key. In the past 2 stroke guys have also suggested checking crank case pressure ( intact), gaskets. Check runout of flywheel and shaft looseness. Any contact scratches on flywheel?

logan01 said:

Check and/or disconnect the kill switch and give it a try.

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I have a good spark with the new plug but I'll give it a try when I tear it down.

Just unplug the wire from the switch. If it still doesn't work, with 2 people if necessary, wiggle the disconnected wire a bit while starting in case the wire is going to ground.

motoman said:

The Ryobi used a tapered flywheel hole with a cast in key. In the past 2 stroke guys have also suggested checking crank case pressure ( intact), gaskets. Check runout of flywheel and shaft looseness. Any contact scratches on flywheel?

Click to expand...

I disconnected the stop switch wires and took the covers off. The flywheel looks OK with no scratches. The magnet is strong. Tried starting with the stop switch wires disconnected but still not a sputter from the machine. One thing I noticed is that when the flywheel magnet is aligned with the coil the piston is positioned before TDC a bit. Checked that with a screwdriver in the plug hole. When the piston is at TDC the magnet is a tad passed the coil. Might that be like timing on a car engine at so many degrees before TDC?

It would be good if we could check timing with a light like on a car. The digging I have done shows that the little 2 strokes which work so hard and well at 7000 rpm do have up to 22 degrees advance at WOT, but I do not know if initial setting is BTDC. Unlike points operated stuff the mags put out a wave that peaks and is used by the circuit in the module to produce spark, so I think it would be hard to static time. But there are 2 stroke guys on this forum who may be able to comment.

Though from an unexpected source and more info than needed, this has an excellent discussion on timing. Beneficial read regardless. 2-stroke timing | Model Engineer

collieman said:

I disconnected the stop switch wires and took the covers off. The flywheel looks OK with no scratches. The magnet is strong. Tried starting with the stop switch wires disconnected but still not a sputter from the machine. One thing I noticed is that when the flywheel magnet is aligned with the coil the piston is positioned before TDC a bit. Checked that with a screwdriver in the plug hole. When the piston is at TDC the magnet is a tad passed the coil. Might that be like timing on a car engine at so many degrees before TDC?

Click to expand...

That is correct.
Ignition fires just before TDC

motoman said:

It would be good if we could check timing with a light like on a car. The digging I have done shows that the little 2 strokes which work so hard and well at 7000 rpm do have up to 22 degrees advance at WOT, but I do not know if initial setting is BTDC. Unlike points operated stuff the mags put out a wave that peaks and is used by the circuit in the module to produce spark, so I think it would be hard to static time. But there are 2 stroke guys on this forum who may be able to comment.

Click to expand...

Well actually you can if you want to.
Scribe a line on the flywheel at TDC, then measure the circumference from the mark, back to the mark.
Divide this distance by 360 and you have the amount of circumference equal to 1 deg.
Scribe a line at 5 deg increments
Use an induction timing lamp and away you go.

Start the engine with a battery drill on the crankshaft nut if there is nowhere you can mark the lines where they are visible with the pull start on.

However there is little point in this as the timing is not adjustable, unless you are checking that a substitute for a NLA module is firing at the right time.

Berts, I am still looking for the ref materials. I have (typically) misplaced them . Logan, I read your reference discussions and interesting they are.


Looking around I did find some "generic" timing curves for small , stock (not race) 2 strokes. At 1000 rpm about TDC-14 degrees BTDC , rising to about 22 degrees BTDC between 3000 RPM and 5000 RPM and then retarding slowly to 14 degrees BTDC through 10,000 RPM . It is interesting that on the small dia (trimmer sized) fly wheels only a small (.028" ) shift in the module position is worth about 8-10 degrees (double check , please). Earlier I had said 20 plus degrees at WOT which is not entirely accurate. Wonder if anyone knows the max RPM of a typical trimmer?. This suggests that any factory tolerance or error in location of the module screw holes can affect initial spark position and ...( not recommending necessarily), some light work elongating the holes could yield some static timing changes, maybe helping starting ?

The patents design of ref I misplaced include advance and retard by way of electronic parts , no points, vacuum or bob weights,