Murray mower won't start after basic maintenance

[csdude55]

I'm a DIYer and really don't want to take this somewhere, but I'm running out of ideas so I'm hoping someone smarter than me can offer some advise

I have a 2003 Murray riding mower with a 10HP Briggs & Stratton rear engine. I haven't done any maintenance in years, but it was having a hard time cranking with the air filter in so I bought a basic maintenance kit with a new air filter, fuel filter, and spark plug. I also bought new fuel line.

I replaced everything, then went to start it up and it wouldn't fire. It would spin slowly, as if the battery was low, but it wouldn't crank and never sounded like it was going to.

So I started to undo everything to find the culprit. I started with the spark plug (the obvious problem since it wouldn't even try to fire), and first saw that the center electrode and side electrode were mashed together and bent out of shape! I pulled the old spark plug out of the trash and saw that the new one wasn't quite the right size, it was a bit longer so it was hitting the side of the engine.

That's when I noticed that the threads on the spark plug were covered in gas :-(

I put the old spark plug back in, but it still wouldn't crank. Upon further inspection, I saw that gas was dripping beneath the exhaust. And the gas tank was almost entirely dry, so I'm not sure if it started that before I began working on it and it's just a coincidence?

With gas dripping, my next theory was that the carburetor was hung open. After taking off the air filter I could see a lot more gas than usual in the air intake, so that confirmed the theory.

I let it sit for a few days to air out, then I pinched off the fuel line and removed the bowl from the carburetor to clean it. The float seemed like it was moving OK, but I removed the float, needle, and pin anyway to clean them, too. I put everything back together, put a little gas in the tank, and opened the fuel line, but still, nothing. Now the engine barely moves at all when I try to crank it.

I didn't see any dripping gas, though, so that's good.

I checked and I'm getting 12V at the starter solenoid, so the battery is OK. And I double checked that it's good on oil.

I went back to the air intake, and used a paper towel to sop up the gas that was in there. Then I went over all of the springs and made sure that they were all working correctly. But still, the engine barely turns at all.

I can turn it by hand, so the engine isn't seized up or anything. And since it turns a little bit when I try to crank it and I can measure 12V then I'm pretty sure that the starter solenoid and starter motor are OK. It HAS to be an issue of gas / air mixture, right?

My next thoughts would be fuel pump or solenoid valve in the carburetor, but both of those are going to be a pain to replace. And it's just such a huge coincidence for something like that to go wrong right after I did some basic maintenance! So before I start messing with those, can you guys and gals suggest anything else?

 

[ILENGINE]

Check the oil to make sure it is at the correct level and doesn't smell like gas. It is not unusual for a leaking carb to fill the crankcase with gas.

 

[Mower King]

I'm a DIYer and really don't want to take this somewhere, but I'm running out of ideas so I'm hoping someone smarter than me can offer some advise

I have a 2003 Murray riding mower with a 10HP Briggs & Stratton rear engine. I haven't done any maintenance in years, but it was having a hard time cranking with the air filter in so I bought a basic maintenance kit with a new air filter, fuel filter, and spark plug. I also bought new fuel line.

I replaced everything, then went to start it up and it wouldn't fire. It would spin slowly, as if the battery was low, but it wouldn't crank and never sounded like it was going to.

So I started to undo everything to find the culprit. I started with the spark plug (the obvious problem since it wouldn't even try to fire), and first saw that the center electrode and side electrode were mashed together and bent out of shape! I pulled the old spark plug out of the trash and saw that the new one wasn't quite the right size, it was a bit longer so it was hitting the side of the engine.

That's when I noticed that the threads on the spark plug were covered in gas :-(

I put the old spark plug back in, but it still wouldn't crank. Upon further inspection, I saw that gas was dripping beneath the exhaust. And the gas tank was almost entirely dry, so I'm not sure if it started that before I began working on it and it's just a coincidence?

With gas dripping, my next theory was that the carburetor was hung open. After taking off the air filter I could see a lot more gas than usual in the air intake, so that confirmed the theory.

I let it sit for a few days to air out, then I pinched off the fuel line and removed the bowl from the carburetor to clean it. The float seemed like it was moving OK, but I removed the float, needle, and pin anyway to clean them, too. I put everything back together, put a little gas in the tank, and opened the fuel line, but still, nothing. Now the engine barely moves at all when I try to crank it.

I didn't see any dripping gas, though, so that's good.

I checked and I'm getting 12V at the starter solenoid, so the battery is OK. And I double checked that it's good on oil.

I went back to the air intake, and used a paper towel to sop up the gas that was in there. Then I went over all of the springs and made sure that they were all working correctly. But still, the engine barely turns at all.

I can turn it by hand, so the engine isn't seized up or anything. And since it turns a little bit when I try to crank it and I can measure 12V then I'm pretty sure that the starter solenoid and starter motor are OK. It HAS to be an issue of gas / air mixture, right?

My next thoughts would be fuel pump or solenoid valve in the carburetor, but both of those are going to be a pain to replace. And it's just such a huge coincidence for something like that to go wrong right after I did some basic maintenance! So before I start messing with those, can you guys and gals suggest anything else?

Might be a bad battery.
First...yes, it's a 12v system but, 12v is not enough in a good battery. Second, you need to check the battery volts under a load, when you engage your starter, and see what your battery V is the moment you engage the starter!
Having 12v, in a 12v battery, and thinking it's 100% good, is a misconception MANY people make!

 

[keakar]

Check the oil to make sure it is at the correct level and doesn't smell like gas. It is not unusual for a leaking carb to fill the crankcase with gas.

this is your problem, every drop of gas that went missing from the gas tank is now inside your engine case and thats stopping it from moving correctly.

buy a new carburetor for it ($16 on ebay) and change the oil and filter before you even try starting it again

 

[csdude55]

Thanks for all of the help! I got it running today, but there are some almost unbelievable coincidences here.

First off, you were totally right about gas in the oil! There's no oil filter in this mower, so I emptied the oil, flushed it with about 1/2 quart of fresh oil, then filled it up with fresh oil.

But... no go.

I had tried jumping it off yesterday and still had everything handy, so I tried again. But nothing.

I took out the carburetor bowl and float again, just to make sure I didn't miss anything. There weren't any jets in the bolt that holds the bowl in so I'm not sure where those are? But still, no go.

Then I took out the spark plug and held it against the frame while trying to start it, and didn't see any spark at all. So I went to buy a new spark plug (which took half of my day, but whatever). I got that replaced, and... nothing.

Then I tried to jump it off again, and eureka!! It finally started!!

I mowed the yard for about 2 hours and all seemed well. Then I turned it off, waited a minute, and tried to restart it... nothing.

So the best I can tell, the oil was contaminated, the spark plug was bad, AND the battery is bad. And the carburetor might have been dirty. Last week it started just fine, but after changing the fuel filter everything else just fell apart.

Either way, it seems to be working now! After I buy a new battery, I guess. Thanks again for the help!