Leaf Blower-NEW ignition coil & still won't start?

[CharBaby]

25cc Craftsman leaf blower about 8yrs old
Was giving me issues starting so, I narrowed it down to the ignition coil - NO SPARK(sometime there, most of the time NOT).
The coil reading K ohms 4.85(spec 2.5-5.0). So, I determined that I needed a new coil. *BTW, spark plug is relatively new and I have other known good plugs to test with.

New coil arrived and tested K ohms of 3.6...good to go?

Installed new coil and adjusted with standard business card/cereal boxtop.
STILL NO START.

Carb is getting fuel. Primer bulb working fine and cylinder is getting gas(40:1). I pulled apart the carb and cleaned/reinstalled. Wasn't dirty!

OK I NEED HELP! WHAT AM I MISSING? Incorrect gap? Spark seems weak but it's present.

I'm not a small engine repair guy but, I can learn.

 

[dlundblad]

Faulty kill switch wiring?

 

[Kamele0N]

Clogged muffler...

 

[Kamele0N]

Plus...when you will remove muffler...check piston trough the exhaust port...if its scratched you might dont have sufficient compresion (carb was set to lean in the past)

 

[Lubener]

I'm with the possibility of kill switch/wiring. Your old coil was still at specs. I don't know why others suggest messing with fuel or muffler when there is a spark issue. Assuming the air gap is set correctly, you could have a rare situation where the flywheel magnets have "weakened" where they are not pulsing the coil sufficiently. You should consistently have a thick blue spark.BTW- you should use a flat feeler gauge to set the air gap. It is very critical and a piece of card stock may be too thick.

 

[wag123]

Originally Posted By: Kamele0N
Plus...when you will remove muffler...check piston trough the exhaust port...if its scratched you might dont have sufficient compresion (carb was set to lean in the past)

+1

 

[CharBaby]

Originally Posted By: dlundblad
Faulty kill switch wiring?


I did disconnect the KILL switch prior to changing the coil and still won't start. And again, I disconnected the KILL switch with the new coil in place...NOTHING! The engine does seems to have compression.

Prior to the no start, the leaf blower ran fine the time before it decided to, "not start"! It's been over a week now that I couldn't get it started. And although it was giving me hard starting issues, when it did start, it ran unbelievably well/strong & no hesitation.

 

[CharBaby]

Originally Posted By: Lubener
I'm with the possibility of kill switch/wiring. Your old coil was still at specs. I don't know why others suggest messing with fuel or muffler when there is a spark issue. Assuming the air gap is set correctly, you could have a rare situation where the flywheel magnets have "weakened" where they are not pulsing the coil sufficiently. You should consistently have a thick blue spark.BTW- you should use a flat feeler gauge to set the air gap. It is very critical and a piece of card stock may be too thick.


The magnets are quite strong. When using the business card, the magnets still pulled the coil right to themselves. I may in fact have the incorrect air gap(too close) although there is no hitting that is causing hard pulling of the start cord. I am not sure of the exact gap as I can't seem to find that spec in order to use my feeler gauges.

 

[CharBaby]

Originally Posted By: wag123
Originally Posted By: Kamele0N
Plus...when you will remove muffler...check piston trough the exhaust port...if its scratched you might dont have sufficient compresion (carb was set to lean in the past)

+1


I will give this a shot! I will look for anything right now however, when the blower was running, it had strong exhaust flow from the muffler. Maybe the exhaust valve???

 

[vwmaniaman]

Does it have a condenser under the flywheel? My umpteen year old Lawn Boy mower had the condenser go belly up this spring and it was a leaky condenser. Put the new one on and now has a hot spark.

 

[Cujet]

If it's a two stroke, and has a reed valve, maybe the reed valve is not sealing/broken/cracked. Preventing fuel/air from reaching the cylinder.

 

[CharBaby]

Originally Posted By: vwmaniaman
Does it have a condenser under the flywheel? My umpteen year old Lawn Boy mower had the condenser go belly up this spring and it was a leaky condenser. Put the new one on and now has a hot spark.


Well, I really don't know as this is only about 8 yrs old. Did they have condenser when this new(if we can call this new)? I'd have to pull the flywheel to find out.

EDIT:
-----------------------
I'm going to say NO. No condenser. Solid State Ignition.

 

[andyd]

OK, tool is too new to have points. Is it a 4 stroke or a 2 stroke ? Little 4 strokes are an unknown to me. This spring, I had a go 'round with my Mantis 2 stroke. No start. I had the yr old carb apart in a old cup on the bench beside where I was wondering what my next move was going to be. Clean as a whistle. I pulled the string. The stupid thing lit, marched down the bench and the cup went flying. I found nearly all the carb parts, except for the piece that holds the needle valve on the float. I needed another carb, but at least I knew I had spark. I had 3 plugs. None fired in the Mantis. I tried them in my chainsaw. After awhile all 3 worked in the saw. I'm guessing I had "gassed" the plugs and they needed to dry out. Anyway. The new carb works. it has new fuel hoses and a primer bulb. I have the carb set rich enough so it doesn't need the choke or prime to run. Both jets are set at 1 1/2 turns out. My understanding of magneto air gap is that it should be as close as possible without hitting the flywheel. A folded sheet of paper between the 2 is all I ever use. I would start with a known good plug, verified by working in another engine. With the carb on, I would pull the engine over without priming or choke. If it pops, I would try a few primes and 1/2 choke.. Good luck, please post a follow up

 

[goodtimes]

A sheet of standard 92 lb. printer paper is about .004". When I set my mower coil I looked up the spec and I used 3 strips of paper, giving .012', which is the middle of the spec. Have to look up the spec to be sure. Maybe the magnet pulls it down .001 more but I doubt it.

 

[WobblyElvis]

Test the ignition system for strength of spark by holding the lead a half inch or so away from the block while someone pulls the starter cord. See how big a gap the spark will jump. Compare this to a known good engine like your lawnmower. If you feel redneck enough you have the jolt travel through your hand to the block and again compare to your lawnmower. Don't do this with your car, beer may be required.

 

[CharBaby]

Yes, I can feel the spark but, it's not intense like on a lawn mower. I can hold the wire and pull the rope myself. Doesn't make me jump but, there's spark.

 

[WobblyElvis]

If it's not like the lawn mower I would say it's an ignition problem. Hold your thumb over the plug hole and pull the cord. Should blow your thumb off the hole as it has compression. Head bolts tight? Pour a little gas [few drops]into the plug hole, reinstall plug and give it a try. If it offers to go for a second and then quits, it's a fuel problem. The gap between coil and flywheel is important. The closer the better in my option. There has to be some gap as the flywheel expands with heat and rotational speed. Find the highest point of the flywheel and install the coil there with very little gap.

 

[Lubener]

Air gap is very narrow for the magneto. I recently changed out a magneto on a Tecumseh and the specs called for .007. You should be able to find your spec online. I would get the proper tool, do it right and not guess with pieces of paper which is a schmuck method..A good working ignition system should be able to generate a spark and jump a 1/4 inch gap. Get on of those adjustable spark checkers. Every DIYer should have one and feeler gauges.

 

[WobblyElvis]

Does anyone know the downside of to narrow a gap in this instance and why? I mean other than physical interference.

 

[CharBaby]

Yes, I have feeler gauges(2 sets) and I will check the gap again. It is quite close I must say!

I will check compression as well. It did(when working) quit once in a great while after starting but then started & stayed running on the next pull.
Originally Posted By: Lubener
Air gap is very narrow for the magneto. I recently changed out a magneto on a Tecumseh and the specs called for .007. You should be able to find your spec online. I would get the proper tool, do it right and not guess with pieces of paper which is a schmuck method..A good working ignition system should be able to generate a spark and jump a 1/4 inch gap. Get on of those adjustable spark checkers. Every DIYer should have one and feeler gauges.


Yeah, the spark in jumping across the spark plug gap but it just doesn't feel strong with my thumb test.