Chainsaw won't start

kcult

kcult

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I haven't begun to investigate yet, but Dad dropped off his Homelite i4550b (might be 20yrs old) because it won't start.

Just for poots and grins, I checked the fuel tank. No gas. He thought there was gas in it, but I told him there was none in it and I didn't have two stroke gas here. A couple days later, he brings me a jug of gas.

He says it's getting spark and the neighbor (a small engine shadetree) rebuilt the carb.

I may get on it today, but I'm looking at that jug of gas. I'm feeling I can't trust it and I'm considering getting some premixed.

Does that seem like a logical approach?
 
Yes, you‘ve already got too many variables. Neighbor rebuilt the carb but didn’t fire it up? The problems may run deep.
 
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I had my mower not start last year. couldn't figure out why and had to drain the gas, open it up, pull the carb, clear it all out. let the lines dry. then put it all back together. got it running with fresh gas...
THEN came the question of "is the gas i was using before any good?"
so i put that gas in the mower to test... it stopped running.
had to drain the gas, open it up, pull the carb, clear it all out, let the lines dry, then put it back together. got it running with fresh gas

I now have a full 5gal jug (combined a few lots of old gas) that i just won't touch and i need to get disposed.

Moral of the story - gas is is cheaper than time spent with that extra variable messing things up. get fresh gas.
 
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DrScaryGuy said:
I had my mower not start last year. couldn't figure out why and had to drain the gas, open it up, pull the carb, clear it all out. let the lines dry. then put it all back together. got it running with fresh gas...
THEN came the question of "is the gas i was using before any good?"
so i put that gas in the mower to test... it stopped running.
had to drain the gas, open it up, pull the carb, clear it all out, let the lines dry, then put it back together. got it running with fresh gas

I now have a full 5gal jug (combined a few lots of old gas) that i just won't touch and i need to get disposed.

Moral of the story - gas is is cheaper than time spent with that extra variable messing things up. get fresh gas.
Click to expand...
The best way to dispose of such gas is to put it in a can you don’t like, put the can in the back of your pickup truck, and then go shop at walmart for an hour.
 
GymB said:
The best way to dispose of such gas is to put it in a can you don’t like, put the can in the back of your pickup truck, and then go shop at walmart for an hour.
Click to expand...
i don't have a pickup truck, or else i would have done that already just for the lulz. my neighbor across the street works at a repair shop and said he'd take it and put it with their stuff. I just haven't taken him up on that yet.
 
I've had good luck with this


in 2 cycle engines. Drain any old gas. Put this in and try to start it. You'll want to get it completely through the carburetor. Let it sit for a week. Dump it out and fill with fresh gas. I've always had them start right up.

Only thing I'll use now is ethanol free
 
kcult said:
I haven't begun to investigate yet, but Dad dropped off his Homelite i4550b (might be 20yrs old) because it won't start.

Just for poots and grins, I checked the fuel tank. No gas. He thought there was gas in it, but I told him there was none in it and I didn't have two stroke gas here. A couple days later, he brings me a jug of gas.

He says it's getting spark and the neighbor (a small engine shadetree) rebuilt the carb.

I may get on it today, but I'm looking at that jug of gas. I'm feeling I can't trust it and I'm considering getting some premixed.

Does that seem like a logical approach?
Click to expand...
You need to turn your bucket over and set the saw on it to ground it. 😝
 
LOL. A few observations.

First, ”most” homeowner mixed chainsaw mixes are only good for a month. After that the oil starts to break down and the fuel mix can damage a 2-cycle engine. I use up my out of date mixes in the closest gasoline vehicle. The tiny bit of 2-cycle oil is not going to hurt anything when mixed into a 15 gallon or larger tank.

Second, what I would do to troubleshoot is to pull the spark plug, spray in some starting fluid into the cylinder, reinstall the plug and then try to start it. If it “pops”, it means that you have spark. Next step would be to put in a few oz of fresh fuel mix and try to start it. If it starts and runs, you’re good to go. If it doesn’t, you need to evaluate the carb and fuel system. If it does not try to start briefly with the starting fluid, you have an ignition issue.

The purpose of the starting fluid is to isolate between a spark issue or a carb issue, before you potentially wear yourself out trying to start it.
 
I may have it figured out, but please bear with me since this isn't my field of expertise and I'm sure I'm using the wrong names for things, but here goes.

Long story short, it looks like the locking mechanism for the trigger is worn and doesn't hold the throttle open all the way when trying to crank it.

After trying errthing, I decided to actually look at the moving parts and noticed when I pulled the trigger, the throttle was wide open. When I let go, it was closed. But when I pulled it again and used the locking mechanism, it let the throttle move back towards the closed position.

20230520_181704.jpg

20230520_181839.jpg

20230520_181942.jpg

I ziptied the trigger, mimicking me holding it closed and...



There may be more involved, but it wouldn't start at all, even after the carb "rebuild."
 
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Tailhunter said:
When he “rebuilt” the carb, where did he set the high and low jet?
Click to expand...

I don't think it was rebuilt. It looks way too clean.

I'm thinking a Chyna swap happened.

Once I figure out how to unwear this trigger lock mechanism, I'll look deeper into that.
 
Hit the open of the carb with a little shot of carb cleaner or starting fluid - just to see if you can hear it try to start , if it doesn’t pop and run for a second - you have other issues than that carb
 
kcult said:
I may have it figured out, but please bear with me since this isn't my field of expertise and I'm sure I'm using the wrong names for things, but here goes.

Long story short, it looks like the locking mechanism for the trigger is worn and doesn't hold the throttle open all the way when trying to crank it.

After trying errthing, I decided to actually look at the moving parts and noticed when I pulled the trigger, the throttle was wide open. When I let go, it was closed. But when I pulled it again and used the locking mechanism, it let the throttle move back towards the closed position.

View attachment 620282

View attachment 620285

View attachment 620286

I ziptied the trigger, mimicking me holding it closed and...



There may be more involved, but it wouldn't start at all, even after the carb "rebuild."
Click to expand...



What do the parts circled do when you pull out the choke with no throttle applied?

.
 
Gator said:
What do the parts circled do when you pull out the choke with no throttle applied?

.
Click to expand...

The best I recall, nothing, but the flap in the far right of the pic opens and closes.

Because I think this is a new carb, I'm thinking the spring on ther circled part is too strong and is taking out all of ther slop in the trigger pin lock.

So, I think I gotta figure out how to reduce the slop or reduce the spring tension (doubtful).

I'm considering asking one of my machinist buddies to make a new pin from steel but with a slightly larger diameter where it fits in the handle.
 
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My last experience with a twenty year old two stroke engine that wouldn’t start, and there was no rebuild kit available, was to let it audibly hear me say it was going in the trash.

I gave it one more pull. Fired right up.

Don’t think for a minute they can’t hear you.
 
First off, I never use pre-mix. Too unreliable
Second, and this may or may not apply in your case but I had a saw a couple years back that I used all day, and at the end of the day it ran out of fuel. I put it up and next day wouldn’t start. Good spark, clean spark arrestor in the muffler, wouldn’t even pop on starting fluid.
Ran a compression test and it was showing like 40psi.
I had simply overworked it and the cylinder scored.
Of course I was cutting up an oak approximately 24” in diameter with a 16” saw.
Good news is I can get a piston, rings and a cylinder pretty cheap. Cheaper than a new saw anyway
If you don’t have a compression tester, take off the muffler and look into the cylinder for scoring.
 
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fieldgrade said:
My last experience with a twenty year old two stroke engine that wouldn’t start, and there was no rebuild kit available, was to let it audibly hear me say it was going in the trash.

I gave it one more pull. Fired right up.

Don’t think for a minute they can’t hear you.
Click to expand...
Deceptions. They are everywhere. Yesterday my wife told me the toaster was making noises, even unplugged. Thinking something had crawled in for a crumbfest I picked it up, opened the back door and as I was tossing it out in the yard I told her it was the decepticons again. She is now seriously concerned I am losing my marbles. I was proud of myself for not shooting it.
ETA. I can be a grumpy mf when something keeps me from getting my first mug of coffee.
 
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