# Mower engine won't fire



## desototjets (Apr 25, 2008)

I bought a used 2006 YTD riding mower a couple of weeks ago fairly cheap.

The guy told me the carb needed to to be cleaned or rebuilt but it would run.

The engine turns over, I've got a spark but even with starting fluid it will not fire at all.

I figured that even with a dirty carb it should at least fire with the fluid sprayed directly into the chamber.

Could it be the timing is off or maybe the magneto is not strong enough?

Any help would be greatly appreciated.

Thanks.


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## justin3 (Apr 10, 2007)

First we need to know the Model and Type of the engine you have, It should either be a Briggs and Stratton or Tecumseh engine. If you get no fire when using starting fluid, you need to look at the basics, I would start with a compression test, seeing as you have already checked for spark.


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## desototjets (Apr 25, 2008)

It's a Briggs and Stratton, 13.5 HP. Isn't there a gauge you use to check compression?


Edit: When turning the crank I do get a suction sound through the carb so I assume I'm getting the correct compression.


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## desototjets (Apr 25, 2008)

Also, the exhaust pipe gets warm when I try to start it so it must be doing something but it's not hitting at all.


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## justin3 (Apr 10, 2007)

I still need the model and type of engine located on the engine shroud. Should be stamped into the front.


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## phillipmc (Jan 27, 2008)

A Model , type and code would be a big help, Also you really need to check compression. A quick easy way to see if it has any compression at all or atleast enough to crank up. With the key turned off and with the spark plug wire off the spark plug, (leave spark plug in) turn the engine as fast as you can by hand by putting the palm of your hand on the screen and twist. Once it hits compression stroke the engine should try to slightly bounce back. What I am thinking is, the exhaust valve is stuck open not letting the combustion take place but still burning the rich mixture in the chamber and sending it out the exhaust. To really diagnose it you need to do a compression test followed by a leak down test. Also Just thought of this. If this is a OHV engine then check your valve clearances. Normally a good rule of Thumb is .004 on both exhast and intake.


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## desototjets (Apr 25, 2008)

I saw where you could check compression by turning the crankshaft in reverse and seeing if you get the bounce back. I tried this and I didn't get it. I suspect it might be the valve stuck open.


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## desototjets (Apr 25, 2008)

The engine is a Model #21B707-0453-E1, 13.5 horsepower, Powerbuilt series with overhead valve design.


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## justin3 (Apr 10, 2007)

If you have no compression, I would varify with a gauge... You either have a stuck valve like you said, or internal damage such as a broken rod.


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## desototjets (Apr 25, 2008)

I took the valve cover off and the rockers appear to be functioning. I'm getting some ignition so I should have some compression thus the rod is not broken, right? Maybe the valve is not closing completely or the rings are worn?


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## desototjets (Apr 25, 2008)

So I finally decided it was going to take major surgery and took the head off. Bent pushrod. Is it safe to assume they are both the same length?


The one that's bent is aluminum. Is that OE?


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## 30yearTech (Sep 14, 2006)

desototjets said:


> So I finally decided it was going to take major surgery and took the head off. Bent pushrod. Is it safe to assume they are both the same length?
> 
> 
> The one that's bent is aluminum. Is that OE?


Yes, that's correct. I believe that they are both pretty close to the same length. You should make sure there are no issues with the valve binding in the valve guide. There is a reason the push rod bent.


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## justin3 (Apr 10, 2007)

I have seen overheated engines with valves completely seized in the head, other times the valve guide breaks loose and binds up the valve. The cylinder head assemblies are not that expensive, around $100


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