Lawnmower hard to start

[BigNick]

We have a 19-year-old Honda 4-stroke lawnmower. I maintain it (change oil, clean air filter, sharpen blade, brush spark plug clean and check gap) every year.

It works great, but lately it has been hard to start (pull-cord). It takes many tries to get it going. Once it's started, it runs without a hitch.

I was thinking it might be the spark plug, which is as old as the mower, but I sort of imagined that if that was the problem, that there would also be problems when it's running.

Any ideas ?

 

[Dimsumkid]

Probably a sticking choke or your carburetor needs to be overhauled/cleaned. A new spark plug can't hurt since it's the original.

You could also try some carb cleaner, starting fluid or seafoam to try and clear it out.

 

[frayne]

Low compression, piston rings ?

 

[travelover]

I'd try squirting a little gas into the air inlet. If it starts right up, your choke may not be engaging fully.

 

[ERD50]

At 19, that spark plug is WAY over due (check your manual). It may not be the main cause, but it sure would not hurt to replace it.

My manual says change each year, but I don't. When it was running rough, I pulled the plug and it looked fine, perfect in fact. But I put in a new one anyhow, since it was 4 or 5 years old, and it immediately ran better.

-ERD50

 

[Midpack]

I'd try squirting a little gas into the air inlet. If it starts right up, your choke may not be engaging fully.

+1. Usually my first option too. Good luck, sounds like my 22 year old John Deere...

 

[Telly]

Honda will want that spark plug for their museum

.....I was thinking it might be the spark plug, which is as old as the mower, but I sort of imagined that if that was the problem, that there would also be problems when it's running.

Well, not quite a valid comparison. IIRC, typical lawn mower engine's governed speed is about 3600 RPM, so with the magneto running at that speed, spark output is high. But your pull-start cranking speed is very low, so the magneto output will be low, so spark output will be low. And this is at starting, a time when everything is less than optimum.

One solution is to pull that cord a LOT LOT faster!

Seriously, a recent spark plug in good condition and properly gapped will sure help.

 

[73ss454]

Ethanol in the gas is causing most of the starting problems in these small engines.
When the gas sits in the tank, carb and hoses it destroys them. You need to clean out the carb and get some fresh gas.

 

[Birdie Num Nums]

I agree with the "get fresh gas" suggestion. I had a similar problem two years ago with my John Deere. After searching around on the Internet, I saw that suggestion, tried it, and it worked. (I had 5 gallon gas can in the shed in which I stored my gas, and the gas must have been 2 to 3 years old by the time I got to the bottom of the can, before I got some fresh gas.)

 

[eytonxav]

A spray of ether can also help start engines, but you have to use it very sparingly or kaboom.

 

[youbet]

I agree with the "get fresh gas" suggestion.

Me too.

A couple of times per year, I put any residual gas from the mower/snow blower supply into my car and refill the can with fresh fuel.

Also agree about putting in a new spark plug.

 

[Birdie Num Nums]

Here is where I found the "try fresh gas" suggestion:

· Dirt in fuel system or fuel is old. Replace fuel with fresh stabilized fuel. Obtain fuel from another supplier before suspecting machine problems. [Emphasis added.] Suppliers blend fuels differently and changing suppliers will generally solve any performance problems.
· Fuel blended with alcohol or ether may contribute to performance problems by causing gum and varnish deposits, especially if fuel is stored for several weeks or more. Obtain fresh fuel.​

 

[BUM]

After years of messing around with domestic internal combustion engine problems, I found that using hi-test gas in all my mowers, trimmers, saws, etc. works very well. Try it you'll like it.

 

[W2R]

My solution to a similar problem with my Honda 4-stroke lawnmower was to hire a lawn guy. Although I must pay him each time he mows, I got a month of free mowing in exchange for my lawnmower (after I had a repair shop fix the problem and renovate it). Then it was not my problem any more.

 

[Payin-the-Toll]

I'm with ERD50--quit posting and change the darn plug already. 19-yr old plug---jeesh!!

 

[BigNick]

That's interesting about the gas. It's from last season, and it's our European "regular" grade (95 RON, 86 MON) which has about 10% ethanol in it. I'll get some 98 RON "premium", which should help on several fronts (fresh, high octane, no ethanol). And change the plug. I'd rather not disassemble stuff unless I have to.

 

[73ss454]

Nick, get the gas without the Ethanol and most of the problems will be solved.

 

[ducky911]

I get ours tuned every mothers day. It breaks my heart to see dw having a hard time starting it.

 

[pb4uski]

Nick, get the gas without the Ethanol and most of the problems will be solved.

I agree - I use non-ethanol fuel when I can find it but it is getting harder to find in many parts of the US. When I can't find non-ethanol gas, I use an additive that allegedly helps avoid the problems that ethanol gas causes.

Whereas I used to store motorized things for the off-season full of fuel with stabilizer, now my mechanics suggest draining the fuel tank.

For OP, I suggest a new spark plug (one could suggest you are taking LBYM to an extreme ) , cleaning the carb with some carb cleaner and a fresh tank of high test (wiht additive if you can't find non-ethanol high test). I would think that would make a major improvement in the starting.

 

[bld999]

"Whereas I used to store motorized tings for the off-season full of fuel with stabilizer, now my mechanics suggest draining the fuel tank."

I try to drain tanks and run till it quits any more. I spoke with a marine mechanic about it, his comment was they saw just as many fuel-fault issues with sta-bil etc, as without it.

 

[ls99]

Stabil is good for several months if added to gas tank. Other wise a squirt of starting fluid works every time.

 

[Sarah in SC]

We are cursed with hard to start small engines. If and when some of them that include a push mower, a chainsaw, a power washer, and the mini-bike start running again, I swear we are going to buy all our gas at the marina (no ethanol). Oh, and that reminds me of the other non-working small engine-the dinghy motor! Finding a local repair guy that isn't backed up 3-4 weeks is a recurring dream around here. That is the job I really want DH to create for himself when he quits the current one.
But I think running non ethanol and running engines completely dry seems to be our best bet.
good luck!

 

[2soon2tell]

Try spraying some cleaner directly into the carburetor. In addition add some Sea Foam or Gumout Regane to the gas tank and most importantly install a new sparkplug. I have used E3 plugs in the past and they have made my engines easier to start.

 

[travelover]

Definitely get a new spark plug and run engines dry before storage. I've had good luck with Stabil in the past, but that was before ethanol in the gasoline.

 

[Walt34]

I was thinking it might be the spark plug, which is as old as the mower...

LBYM and frugality are wonderful characteristics but sometimes ya gotta just live large, bite the bullet, and blow a wad of cash.

Buy a new spark plug. That one has long since deserved ER.