Lawnmower hard cold-start - works fine otherwise. How to fix?

[mazzgolf]

Have a 15 or 20 year old lawnmower. Past few years, it has been getting harder and harder to cold start. This year it's worse than ever. Press prime bulb three times, pull several times, nuttin. Prime it some more, pull several times, nuttin. Rinse, repeat. After a few attempts like that and getting nowhere, I spritz a little starter fluid directly into the carburetor (take the air filter off, spritz in the intact there, put air filter back on), and magically it starts on the first or second pull. Had to do this twice already this year (first two times using it this spring, had to do starter fluid thing once last year, too).

After that, it works fine. Hot engine starts fine on first or second pull. Engine runs perfectly normal - no sputtering, and no weirdness like that. Runs like a charm.  But put it away, take it out next week, and the process starts all over.

Things I've done already:

* I never leave gas in the mower over the winter. I always burn it all out (run mower till it stops).

* I have taken this mower to an engine shop every other year for the past few years to get a "tune up" - new plug, new air filter, etc. So the plug should be fine. Air filter is a little dirty now but, I don't think that's it.

* Last year when I was having this problem, I took the carburetor off and cleaned it completely, reassembled back on the mower. Kinda helped but not really, obviously since it still happens.

What should be my next step to figure out how to solve this problem? (aside from buying a new mower which I thought about, but the thing works absolutely fine once I get it started the first time!).

I can't think of what it could be.

[Yobuck293]

20 years old?  Mower owes you nothing.  Buy a new one and retire it.  

[CJ3a]

I would start with a new plug.   It will probably be fouled after the failed attempts to start. 

[mazzgolf]

1 minute ago, CJ3a said:

I would start with a new plug.   It will probably be fouled after the failed attempts to start. 

Wouldn't a fouled plug cause sputtering while running? Or hard-start even with a warm engine? I thought if the plug is fouled, the spark will be bad and that would affect everything - starting and running.

[BCsaw]

Carb adjustment

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[Greg]

Carb aint happy. Starting right up on fluid indicates fuel issue.

Give it a good cleaning in an ultra sonic parts cleaner. Pull the main jet and the tube behind it. Crud will also get into the passages for air mixture screw which will be higher up on a side, just count your turns out to reinstall. Also use new intake gaskets. At 20 years old they gotta be beat if not replaced and should be replaced every time carb is removed. Old as it is can try and find carb rebuild kit if still available, only rubber/seals will be in/on the inlet valve and bowl, but if they where bad you'd be flooding out and leaking out of bowl gasket.

 

I've had a couple carbs at work that had to be cleaned a couple times to straighten them out.

Edited April 23, 2022 by Greg

[username]

+1 on the carb.  Have you fiddled with it while cold and trying to start?

Also, I do the same - draining gas.  However, I leave the cap off for a few days and tilt the mower/blower/generator in a few different directions each day.  If all you do is run it dry, there's still some gas left which is more than enough to gum up some incredibly small gas throughputs.

Before I do anything, I try seafoam.  My lawnmower is a dozen years old and started on the first pull this year.

Edited April 24, 2022 by username

[Coyoteslayer]

Had the same issue when my daughter poured bubble solution in the gas tank!! Got it to run but never was the same. Next year got the ego 60v mower. Wish I did it sooner. No more carb to mess with or bad gas lol.

[CJ3a]

A bad plug will cause hard starting but may not cause it to run bad.   If it will idle,  throttle up and run under load the carb is fine. 

[Greybeard]

Carbs wear down over time.  Rebuild it or it may be cheap to get a new carb online.  After 20 years I'd be looking to get a new mower.  Use your man card, now's your chance.

[Bucndoe]

Seems like a carb issue. Take it completely apart and throughly clean it. The smallest piece of grit in one of those small openings can cause an issue. Is your fuel tank clean ? If you can take a carb completely down, clean, and replace it you don't need to waste your money at a mower shop

Edited April 23, 2022 by Bucndoe

[mazzgolf]

I took apart the carb last year and thoroughly cleaned it. I did see some gunk in the small holes I remember cleaning out. I had that carb looking pretty good when I installed it back on the mower.

The fuel tank - as much as I can see inside of it, it looks clean to me.

I often wonder about when running it dry where the gas in the carb goes. I assumed running it dry will blow out the gas in the carb, too.. maybe not? Maybe I'll take the carb apart again and look at it.

But it is just weird to me that it happens on cold-start only. Runs fine, and starts fine when hot. But I'm a computer guy - when it comes to actual physical moving machines and parts, I know very little. 

[hunterbob1]

4 minutes ago, mazzgolf said:

I took apart the carb last year and thoroughly cleaned it. I did see some gunk in the small holes I remember cleaning out. I had that carb looking pretty good when I installed it back on the mower.

The fuel tank - as much as I can see inside of it, it looks clean to me.

I often wonder about when running it dry where the gas in the carb goes. I assumed running it dry will blow out the gas in the carb, too.. maybe not? Maybe I'll take the carb apart again and look at it.

But it is just weird to me that it happens on cold-start only. Runs fine, and starts fine when hot. But I'm a computer guy - when it comes to actual physical moving machines and parts, I know very little. 

When storing for the winter do you have an inline fuel shut off if not get one they're cheap you can do it you can keep the gas in the tank put some stabil in it run it  then shut off the petcock only takes a minute when it's starting to die manually put it on choke that'll empty the carburetor bowl.When it's cold how many times do you press the primer bulb do you do it till gas comes out the carburetor.After it's hot and it's shut down do you still have to press the primer bulb to start.

[mazzgolf]

6 minutes ago, hunterbob1 said:

When it's cold how many times do you press the primer bulb do you do it till gas comes out the carburetor.After it's hot and it's shut down do you still have to press the primer bulb to start.

I press the bulb anywhere from 3 to 5 times before attempting to pull. After pulling my shoulder out of its socket pulling several times, I repeat the cycle again  After priming/pulling 3 or 4 times, I spritz with the starting fluid and it starts up fine after a couple more pulls.

After the engine is hot, I never have to press the bulb to start. Usually one or at most two pulls (without priming) and it starts right up.

Oh, one only thing I remember now. The reason why I took apart and cleaned the carb last year was the mower was cutting out/shutting off after running only a few minutes. I would get it to start, then it would shut down soon after. When I took the carb off and cleaned it up (and when I say I took the carb off, I only mean I took the bowl off), a lot of gunk got cleaned out of that little hole on the main jet/bowl nut. Cleaned the bowl, too, then put the carb bowl back on and it ran fine (like it is now). But even before that, the hard cold-start was still a problem.

The carb float was operating fine, BTW. I don't see any problems with the float. I did not change the o-ring gasket around the bowl.

This is pretty much how I cleaned it minus the replacement of the gasket: 

 

[hunterbob1]

When it was running and shutting off, chances are the float was sticking, or that tiny looking square pendulum thing but you cleaned it and got it free so that solved that problem. If the carb bowl is not leaking you don't need to replace the gasket. Is the bulb attached by a 3/8 bolt or a with a threaded bolt needle with a spring. By the way what make mower in engine.