Lawn Mower Help
 

help, my lawn mower is acting up!

started to mow today, and got ~5 min into it when it started to act as tho it was starved for fuel.

it started fine as always and after running great for several passes, it wanted to stall. in fact, i had to stop it since it would not cut out alone. it will continue(every time) to start strong and maintain for about 10 seconds before struggling to stay on.

just a little background and history...

fairly new spark plug
burns oil, so the plug and air filter(also fairly new) were cleaned and re-oiled respectively, after this issue started to no avail
oil level is fine
took the muffler off w/ same result
it is ~9 years old
carb connection is fine(my edger had starting issues because the carb hose was not fully engaged)

i do not want to take it to a mower shop(too much $$$), that's why i'm asking for your help. i'll sooner buy the reel mower i've been wanting.

i thought carb, but why does it start and stay strong for a short time, every time?

thoughts?

Sounds like fuel starvation. Check fuel filter, water in the gas/a piece of floating rust/crud blocking the main jet.

Does the carb have a float bowl? If so, remove it and see what's in there. Sounds like the gas is trickling in slower than the engine is burning it. When it dies, enough trickles into the bowl to get it full enough to immediately start again.

Also look in the tank to see if floating crud is blocking the tank outlet (where gas enters the line to the carb).

Another thought- loosen the gas cap and see if it runs better- if the cap is not venting right a vacuum can develop that keeps gas from flowing to the carb.

if the problem is water in the tank (and you suspect that it is) you can put some alcohol (IPA) in the tank and stirr it up. it will run like crap until the alcohol gets out of it but it should run the water through it.

Also check the choke. It may be sticking.

Since there's a lawnmower thread going already, I'd like to add my lawnmower question to it. If you don't care about my long background story, scroll down to find the actual question.

Background: I'm a complete idiot when it comes to lawnmowers, as I have use a reel mower for most of the time I've lived in his house (my lawn is about 10% larger than a postage stamp). Before this place, we lived in apartments. (As a kid, I was trusted to use the mower, but never to maintain it).

So, I have this 3rd hand mower I know next to nothing about. I was told it needed a new spark plug, but it would start if you used starter fluid with it. It worked fine for a season (with starter fluid), then I bought a reel mower (see above) when it ran out of gas. Now we are about to move, before selling this house, and I'd like to get the old mower going again, to minimize the time and effort required to maintain the old place, since I'm going to have to care for two houses at once (and I don't have a Pickup, so I don't want to be hauling a mower back and forth). I replaced the sparkplug a few days ago, but I haven't put any gas in it yet, because I need to know:

The actual question: How do I tell if I need to mix oil with the gas, and how much to use if I do? Also, can I just use stanard (or synthetic) motor oil for a car, or do I need to buy special lawn-mower oil? I have a couple of individual quarts of miscellaneous oil leftover from buying cases, so I figured if wouldn't cause serious problems, I'd just use that. (Not that I'll need two quarts for a couple gallons of gas, right?).

Also, do lawnmowers have oil that isn't mixed in to the gas? How often do you need to change that?

Here's the only other piece of info I have about the mower: It's a Murray.

P.S. Feel free to laugh at me for being completely ignorant of this stuff... :D

The first thing I thought of was a clogged air filter, but you said it has a new one. Have you tried starting it with the air filter removed? One way to find out if it is the fuel system or not is start it and when it starts to run rough spray some carb cleaner into the carb if it comes back running strong you'll know it's in the fuel system. It sounds like trash or water in the carb not letting it get the fuel it needs to run smoothly. I'd take the carb off and disassemble and clean it good with carb cleaner. If there's water in the gas you'll be able to tell when you take the bowl off of the carb.

If it's a Murray it most likely has a Briggs & Stratton 4 stroke which means it wouldn't need the gas and oil mixed. Also if it has an oil sump it doesn't need oil in the gas because that is what the oil in the gas does in a 2 stroke keeps the motor lubricated. Most lawn mower manufactures recommend using straight 30 weight motor oil. Multi viscosity motor oils will cause them to use more oil. Most push type mowers with 3-4 HP engines hold about 20 oz of motor oil and the recommended change interval is 25 hours or at the end of the season whichever comes first.

it does sound and act just that way. but, what do you do with an auto choke?

Erik, Beef, and Ford Man,

thanks, i'll try looking @ the carb and fuel. not being good w/ this type of thing, if i tear the carb apart and can't get it back together, the new reel mower search will be on!

ok, just took the air filter off and put the throttle wide open...

i could see the throttle moving back and forth by itself w/out the filter before i manually "got on it."

Its fine if the throttle plate moves on its own- its hooked to a governor that automatically opens the throttle when the engine is running slower than it should.

It could be that you saw the choke valve- it should close when the engine isn't running and open when the engine is running.

What I did on my mower was move the spring on the govenor to a hole higher up, it allowed the motor to run faster so it would not stall out.

-Jay

thanks! looks like i got a lot to learn about mowers.

taking a break right now(dinner). but, i've torn it apart, cleaned the carb, and emptied the gas tank. let's see if i can put it back together...

I'm just curious- was there any junk or water in the carb bowl or tank?

Dinner @ 4:05? You certainly are on Florida time! I just got back from Lunch here in Virginia. ;)

-Jay

The only two problems I have with small engines are water and crud in the carb jets.

The water can be drained from the bowl or gas tank, depending on the model.

The crud manifested itself by surge-die-surge-die-etc. I wound up pulling the paper off a bread tie wire and reaming out the carb jet(s). I've used Sta-Bil ever since and never had that problem again.

Once in a while my dad would remove the needle valve and spray it down with carb cleaner. He never used Stabil, but the last time he used the mower in the fall he would let it sit and idle until it ran out of fuel, then put it away for the winter. - this way there was no old gas left in it to create varnish over the winter.

-Jay

If the mower has been sitting for several months with gas in it it is very possible that the gas has gummed up the carb, but the carb cleaner should take care of that if that's the problem. Stabilizer is a good idea if you're going to leave gas in it between seasons. I always fill my motorcycle up with gas in the fall and put stabilizer in it then run it a few miles to get it all throughout the fuel system. Usually that tank will last for what little riding I do during the winter months, but if I need to refill I just add more stabilizer.

there was a bit of build-up in the carb. now, the good, the bad, and the ugly...

the good: got it going and finished mowing. runs like a champ; thank you, one and all! :thumbup:

the bad: don't know how i fixed it...besides cleaning the carb, i fooled around with the linkage during re-install. which fixed it?

the ugly: there will be no shopping for a reel mower, at least for now.

https://smiliesftw.com/x/big_rofl.gif

Ok, now that that's out of the way, someone else mostly answered your question. To rephrase and add a little...

- If it's a 4-stroke engine (most likely) you don't mix oil into the gas. Look for a tag with the model and serial number to look it up and find out if it's 2 or 4 stroke. Look for an oil plug/fill hole, maybe near the bottom of the engine; if there is one then it's probably a 4-stroke engine. Change the oil, it's probably awful by now.

- If it's a 2-stroke engine (possible), you probably will have to mix oil into the gas. You must use oil made specifically for the purpose. You'll have to find out what ratio to mix it at; that same model number you looked for as I suggest above could help, or it may be marked on the gas tank, or it may be a mystery. The nice thing is that if you know the ratio, you may be able to buy 2-stroke oil that's prepackaged in measured bottles so you just dump a whole little bottle of it into a gallon of gas.

- If it's a 2-stroke engine that mixes the oil automatically (highly unlikely), you'll need to find out exactly what type of oil to use with it.

Cleaning the carb almost certainly did the job.

Oil mix 2 strokes have the carb attached to the crankcase. Four strokes have an oil sump and the carb feeds to the valves in the cylinder area.

regards
gary

Bowtie, it's very likely that there was some sediment in there somewhere. We had virtually neverending problems with this on our previous mower because it simply didn't have a filter. We got so frustrated with it in general that we replaced it with a better one. (Although now we are wishing we went with electric rechargeable instead of gas.) Anyway, if there isn't a filter in the tank, be sure to install one inline.

The neighbor lady asked me to look at her mower since it had died in the middle of mowing and wouldn't restart. I do all her mower work (and the lady on the other side, too) and sharpen the blades when they need it.

Her mower's spark plug was COVERED in soot. I've never see one so bad. I wire brushed it clean and reinserted.

Looking upstream to see what did that found an air filter that hadn't been cleaned in four years. It wasn't passing any air. Her comment: "These things have air filters?"

A cleaned plug and cleaned filter...started on first pull.

Blade was still sharp from last time. Back in service.

Another job well done.

fantastic idea! thanks.

had some carb issues a while back with my wife's 86 Z28. the tiny carb filter is apparently pathetic, so i installed an inline filter just before the pump. much better since.