Mower won't start

[mike]

I have a Scotts 229630x8A mower with OVRM 120 engine.

Bought it used, so unknown history. Was difficult to start first season, but worked.

Now, it's extremely difficult to start, but runs fine if you get it started. If I shoot it with starting fluid, it fires once or twice. Does backfire thru the carb a little, that's why I checked for the sheared key.

If I can get to the priming pump fast enough, I can sometimes get it to run. Runs fine afterward. Starts first pull when hot. Back to not starting when cold.

Symptoms point to not getting enough gas.

Has spark. New plug. Fresh gas. New air filter. I've rebuilt the series 8 carburetor twice. Yes, I put in the float valve seat the right way. Checked valve adjustment. Took off the flywheel nut to verify the key is not sheared.

I haven't checked compression...this is the first OHV lawnmower engine I've tried to fix. The compression release probably affects the compression measurement anyway???? I don't know what to expect.

I like this mower because it mulches the grass very well. I'd like to make it run.

Suggestions?

[bob_villa]

It is fairly common to have the wrong key..."Scotts" doesn't tell us the motor brand? There is one on Youtube and it's a Tecumshit motor...you might have to get the model and serial and make sure you have the right key for the fly.

[Tony Hwang]

Sounds like fuel delivery problem to me. carb. or fule passage. I just plug up the spark plug hole with chewed up paper ball and if it pops when I pull the cord. That is good for me for compression. I have an old John Deere mower, first start at the start of season it takes about 10 pulls to start. after that 3,4 pull starts it always. To store it at the end of season I run the engine until fuel tank goes empty.

[Stormin Mormon]

My first two thoughts are leaky intake valve, and bad carb to engine gasket. Possibly also choke not closing. Well, that makes three.

- . Christopher A. Young learn more about Jesus .

. .

[bob_villa]

It doesn't have a choke, it has a primer...and you always say a leaky cab gasket. I've never seen that...I'm sure it does happen, but not as often as you think. Tecumseh Engine Model: OVRM120 FAMILY: YTPXS.1951AA Displacment: 195

[trader_4]

Does the priming bulb inject fuel into the carb throat when it's pushed?

[clare]

Dose the fuel with sea foam to clear the carb and put in a new spark plug. Run a tank full of fuel with heavy dose of sea foam.

If at all possible run ethanol free (here in Canada shell premium is ethanol free)

[clare]

It's a non-adjustable carb - set on the lean side to start with for emission reasons - leaned further by ethanol mix, and even more if any gum has deposited in the jets.

[Stormin Mormon]

Hope so. I've also seen more than one or two cases of bad carb to engine gasket. The choke closes, but there is so much blow by air, not enough gas mix gets in.

- . Christopher A. Young learn more about Jesus .

. .

[J Burns]

I've got a second-hand walk-behind with a Tecumseh engine. A decal or the manual said to press the primer 3 times. I had to press it a lot more. Then I learned that each time you press it, you're supposed to hold it. I don't know how many seconds is recommended. I think that's true of the OVRM120, too.

It still took more than 3 presses. I couldn't get the primer apart. In the last year, after several years, it has improved. Maybe at some point I put a little Sea Foam in the tank, and that cleaned it up. I don't remember.

[mike]

yes. That's how I get it running. Prime it Shot of starting fluid Pull the cord a lot If it kicks over, it will die quickly. If I can run to the side and start pumping the priming bulb, I can keep it running long enough to warm up...starts easy after that.

[Unquestionably Confused]

How about crap in the gas tank. Not enough crud to block the fuel flow completely, just enough sitting there to prevent the engine to run on its own until your screwing around trying to start it dislodges enough to get going.

Had that problem recently with a large mower. Would start up and then die under load. Filter looked okay but only partially filled with gasoline. Removed the intake to the fuel pump and there was just a trickle of gas. Blew back into the line, heard it gurgle in one the tank and then gas flowed freely. Worked fine after that due, I suspect, to it bouncing along as I mowed.

As it's a Zero-Turn Bobcat, I'm not looking to pulling out the fuel system from two saddle tanks but suspect that's what it'll take before long.

[J Burns]

Each time you press the bulb, do you hold it several seconds?

Have you taken the primer apart?

[Ralph Mowery]

Check out the 'bolt' that holds the float bowl on. I am thinking that engine has a hole in the end and also a very small hole on the side. That hole on the side is very small and hard to see, not the great big one near one end.

[mike]

Yep, I've read the manual and watched a zillion youtubes. Got all the tiny holes I could find. Pumped a can of carb cleaner thru it. The gas tank is very clean inside as was the carburetor.

I've rebuilt a dozen auto carbs and motorcycle carbs over the years. Never did find anything wrong with any of them, but they worked after reassembly. Until now.

[mike]

The consensus seemed to be that you push it FAST and about a dozen times. I've tried every combination of number and speed and force that I can think of. Bulb appears to squirt gas out to the input side of the carburetor.

I didn't see the need and didn't expect I'd get it apart without damaging the rubber part.

The primer seems to be what keeps it running early in the start process.

I didn't mention that I popped the cover and took out the idle jet and cleaned all that stuff too.

This is all very frustrating because I can't come up with a rational cause that fits the symptoms.

Only thing I haven't tried is to look at the valves.

If I stuck a compression gauge on it, what should I see at speeds I can muster with the pull starter? The compression release is a wild card with which I have zero experience.

[Fat-Dumb and Happy]

I'd take the bolt/jet that hold the bowl on the bottom of carb off and let some gas run out till you are sure there is no fuel delivery problem to that point. Be sure the cap is venting properly. I've been finding a lot of water in mower gas tanks and carbs (including mine). Like others said only 100% gasoline in the small engines. Adjust the valves, it's not that hard to do. You should also be able to keep it running by taking off the air cleaner and choking it a bit with you finger to keep it running until it warms up. These things are like playing amusical instrument. Stay after it.. check the cables and make sure the safety brake isn't dragging. If you want to try it you might try finding a jet/carb bolt with larger jetting or very and I mean very very slightly make the jets a little bit bigger using a welding torch cleaner although that isn't supposed to be done or needed. Best advice I know is be sure to use only 100% gasoline. I once had a weird one, the spark was jumping to ground because of a cracked coil, but it would fire and almost run. Sometimes for whatever reason a good old spark plug works better than a brand new one. Don't give up... just one more pull on the rope and if the rope breaks... well fix that also.

[Stormin Mormon]

Used to have to crank the blade backwards to check compression.

- . Christopher A. Young learn more about Jesus .

. .

[J Burns]

Mine is on a Craftsman mower, so I don't know the Tecumseh model number, but the family is YTPXS.1951BA. That sounds pretty close to yours.

A decal on the engine simply says to press the bulb 3 times. I found that even pressing it 10 times didn't do much. Then I read online that I should hold it down. Now sometimes 3 is enough.

I shined a light in my carburetor but didn't see any gas squirt. This manual seems to say they all work about the same way. Online, I read that the bulb pumps air, which picks up gas by venturi effect.

Mine usually stalls in a few seconds. I press the bulb one more time, holding it about 3 seconds. Then the engine will start and keep running.

The manual says if I remove the bulb, there are air passages I could clean. Removing the bulb would destroy it. Sears' price is $9.75.

I guess my primer system doesn't work very well. Maybe it was designed as a theft deterrent. If they see me trying to start my mower, they won't steal it.

[bob_villa]

If it has a fly-key like this:

I would change it as a matter of course...it's not expensive.