Is it smoking when running? Does it sound like it is misfiring?
Sounds like it is starving for fuel. Check fuel filter.
It can't hurt to change the plugs.

MU

 

Check plugs, and fuel filter. Also may have a clump of something in the carb.

 

Yes ...i was thinking that i should probably change the plugs anyway. Didnt think about the fuel filter. Anyone know where the fuel filter is located on this machine? It it located near the carb?

I read another forum where carbon can also be a culprit. I'll start with plugs and a fuel filter .... and then look at cleaning up the carb if that isnt the problem. Might not be able to get to this today but will follow up.

 

Carbon won't do any but engine need 3 things is spark, compression, and gas so I am think it carb got varnish in it.

Look on gas line and see plastic stuff that is fuel filter. If it not then carb need clean.

 

Actually, a flake of carbon stuck under a valve seat will do that.

 

When you said your mower "suddenly" lost about half it's power, I'm thinking your 2 cylinder motor became a one cylinder motor. I hope I'm wrong.

 

I actually thought the same thing. I hope you are wrong too (unless of course it's the spark plug)

 

My first thought was the same thing bontai Joe just said. I don't know about the ignition on that engine, but would imagine it fires both cylinders everytime. Kinda hard to loose just one cylinder due to ignition in that case. Maybe a plug wire came loose, or possibly melted on something and is now grounded to the block.

 

Sounds like your coil died.... Or plug...

 

update:

I didnt have alot of time last night since the wife had other projects for me. I did manage to run to my local Home depot and pick up two new plugs, air filter and a fuel filter. I replaced them last night but was unable to start the machine because it was too late and I didnt want to upset the neighbors or wake my 11 month old twins.

This morning, i fired her up. She seems to be running better but still not at full strength. Im sure the old fuel filter was somewhat clogged so that probably helped. I mentioned that prior she was running at about 50%. I would say that she is up to about 75% power. It's better but not good enough to get those blades spinning fast. I must mention that there appears to be occational missing so im wondering if there is some spark issues?? What causes some misfiring ....bad coil? Anyone know where the coil is located? I might have to pull off the covers that hide the plug wires. Also, I havent yet dug into the carb. I will try to follow up in between work and infants

 

Before you dig into the coil you can do a qwik test that has worked for me before. It will sound crude but works.
With tractor running spray plug wires with water. If the wires arc and engine misfires even more than the wires may be bad along with coil. Or if that is not to your liking, You can also use a test light (sharp pick type) to ground out each cylinder to verify which one is bad. Maybe you'll get lucky and only have 1 bad wire.

If you eliminate the electrical system, I would remove and clean the carb.

MU

 

how much water.....a mist or a direct stream? I only see about 1 inch of wire before the boot that goes on the plug. Can i spray the water on that very short piece of plug wire?

 

Just a steady mist. You want to make sure the water shorts it out if that is indeed the problem. You'll also have better luck if you do it in the shed or garage, or at night so to see if indeed there is an actual arc from a short. Leave the door open!

Like I said if that seems crude you can short them out using a pick with a wire attaced to the shaft. Attach the other end of the wire to the frame for a good ground. If you don't have a pick / test light you can butcher an old phillips screwdriver sharpen to a point. Stab the tip right through the boot. If the engine runs (check both sides) the same then obviously there is no short in the wires.
Most important,make sure you not to touch the metal shaft (srewdriver etc) when doing this or you will get a charge!

MU

 

Ok ...had a few minutes before rushing to work.

I ran the mower for about 2 minutes this morning and turned it off. RIght before leaving for work, I popped open the air filter casing and removed the new filter. It was soaked in gas. the bottom of the air filter housing had a layer of gas. At the bottom of the air filter housing (once the filter was removed) there was a flat metal plate about 3 inches long held by screws. I took off these two screws and noticed what appears to be the carb float on one end and a small hole (gas line). It appears that the gas comes up under this plate and tunnels into this hole (that I believe is the carb) I've never dealt with a small engine and it's been several years since i've even messed with a carb on a car. There appears to be a carb float completely open (looks about the size of a quarter). I tried to move the float and it wont budge.

First, Im not sure that this is indeed the carb float and whether or not it should open and close. From what I recall (back in the day) the float on a automobile carb should open and close fairly easily. DOes the same apply to a garden tractor?

Also, I have no idea why everything was saturated in gas??

 

Oh you got some dirty in jet where carb's valve cause stuck make hard to move float. Well you have no choose well you need do carb clean now.:sorry1:

 

You mention something about a part the size of a quarter. That sounds like a butterfly valve to me. Probably brass colored, and slightly thinner than a quarter. I'm betting it's your choke.

A stuck intake valve can cause fuel to be blown out of the carb, but it sounds like you have a lot of gas in the air cleaner. More than likely the carb is flooding over.

I'd start it up with the air cleaner off and see if gas is being pumped or blown out of the top of the carb. It would look more like it's being pumped out if the carb is flooding. If that's the case you might give the carb a few love taps with a nylon hammer or a screwdriver handle. Don't beat the crap out of it, just smack it enough to kinda rattle it. Sometimes you can have a piece of crud in the needle and seat, and this helps knock it out of there.

 

You know, i was thinking that might be my choke right after I posted. Yes ...it is brass colored and thinner than a quarter. I'll move the choke lever to verify that it is indeed the choke. If so, how would i get to my carb? would I have to remove everything?

I like to think im somwhat mechanical but never messed around with carbs before. I'll try starting the tractor with the filter housing open and check for fuel "pumping". If it is ....perhaps I can have a mechanic look at it ....unless you have other suggestions

 

Was the choke funtioning properly? If it was stuck closed I think you found your problem.

 

If you short out one cylinder at a time, (you can pull the wires one at a time) you can tell which cylinder is giving you the problem. It will make the least difference in the way the engine runs. You may want to pull the covers off and take the heads off to check that the valves are seating properly.

 

Another thing you could do after you check everything is get some SeaFoam and put it in your gas tank and then run it. If there is something in there this might just fix your problem.

 

The choke is mounted right in the top of the carb. You probably still have the lower part of your air cleaner on. Take that off and you should be able to get to the carb easily.

Pulling plug wires as mentioned above is a great way to isolate trouble. Just be careful not to get shocked. I have a special pair of plastic pliers designed just for that purpose.

 

Im still at work so will try to do this tonight before it gets dark and before the twins go to bed.

1. I'll verify that the "quarter like" float is the choke. I believe it is and I believe it works good.

2. I'll run the motor with the air filter off and air cleaner casing open (looking for a pumping of fuel

3. I can try the spark plug test. Let me get this straight. Start engine. As it runs, pull one plug boot off spark plug ...listen to engine. Reattach and then pull the other one too....listen to engine. Is this correct? I have a nice pair of craftsmen vice grips with a thick rubber handle. Will this and a pair of dry gloves keep me safe from shock?

 

Here is the latest update:

This evening I verified that the quarter like float was indeed the choke and function correctly when I slid the lever up and down. With the engine off and with the choke wide open, I looked down and moved the throttle level. Everything seemed to function good and I was able to see the carb float moving.

I started the machine and it ran. at half throttle you could hear pops (about every other second), followed by a small puffs of smoke coming up through the carb opening as each pop occured. Not sure its considered backfiring. I didnt see any fuel coming out and the air cleaner tray remained dry throughout my test. As i increased the throttle, the pops would intensify and get much louder and faster (almost 2 every second) ....almost sounds like a 22 handgun. occationally i would see a little something pop out ....not sure if it was small pieces of grass or some type of ash. I turned off the mower and removed the air clean. Again, i started it up and it seemed to run fine ...except for these pops. It was extremely loud without the air cleaner on top ...so it was hard to judge the power of the mower. At half throttle ....it ran pretty decent except for occational popping. At full throttle, the popping, followed by small puffs of smoke grew much more intense. At times, they almost stalled the machine.

I couldnt perform the spark plug test but didnt want to try until i was sure i could do it without getting shocked.

Anyone know what might be causing this popping (possible misfire or backfire)?

 

Well we already have experiences with shock from spark plug it not hurt you but feel chill on arm.

Most strange feel was old 60's brigg 16 hp with pointer and I don't know I was hold spark plug during run for about 10 seconds until I feel weird.:fing20:

Well you need try switch spark plugs because too I was try mow it will keep pop then stall. I know what sound you talk about.

Can you change spark plugs?

 

I would think you would be alright with your with your pliers and gloves. I've seen guys do this with bare hands...never had much luck with it myself. At any rate, it sounds like that should be your next step. You're looking for a weak cylinder, so you want to see if one makes less of a difference when you pull the wire.

Somebody earlier mentioned carbon stuck on a valve. That's looking like a good possibility. Do you by chance own a compression tester?

 

Im thinking valve problem. Burned, a peice of crud, loose seat etc. Do a wire pull test to see what cyl, and then I would be pulling the head.

 

Keep your other hand in your pocket... The spark wont jump to you if you don't complete the circuit...
A bad plug will make the engine pop.
Also a valve seat that came loose will do the same...

 

Not sure that I can work on this today but I'll try the spark plug test tomorrow morning.

I've never really gotten down into valves and head removals before. Since the machine is dual overhead valves, can I just remove the two covers and check for problems or must the entire head come off? Once I indentify the problem cylinder, do you recommend I pull the covers off or shall I have a small engine repair person look at it?

Also, someone mentioned "seafoam". This is used to remove water and carbon buildup. Do you think this will help or shall I save my $6?

I really appreciate everyone's time and input