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I have a 2005 scag tiger cub 48 after mowing for half hr or so the mower stall as if out of gas,I cleaned tanks,replaced fuel pump and filters new caps,I also replaced seat switch,fuse holders,cleaned battery terminals,runs fine when running,just keeps stalling.

Check valve clearances. If too little, and as the engine heats up and things expand, it could mean that a valve is not completely closing.

chance123 said:

Check valve clearances. If too little, and as the engine heats up and things expand, it could mean that a valve is not completely closing.

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did ,still stalls..

What engine are you running?

chance123 said:

What engine are you running?

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kawasaki 19hp

An engine needs three factors present and in the correct proportion to start and run properly - the correct air/fuel ratio (fresh, quality fuel is a must), sufficient compression (arguably 90 P.S.I. or better) and sufficient spark at the correct time. If one of these factors is missing or out of proportion, the engine will run poorly or not start/run at all. Your task is to find the missing factor by inspecting and testing the systems involved. Which factor is missing or out of proportion in your case?

If you do not know how to check for spark or perform the necessary checks and tests, youtube has some videos that will guide you through the process. Simply search youtube for what you want to test or check.

There are conditions that will prevent an engine from starting even though all three factors are correct such as a plugged muffler/exhaust, old/contaminated fuel and I am sure there are more possibilities but I will not try to list them all here so I am going on the assumption that one of the factors is missing and that all other components are functioning properly.

You will need a compression gauge to test compression so if you do not have one or do not have access to one you will need to take it to someone who can test it for you. You will also need a spark checker which can be made from an old, working spark plug by clipping off the side electrode, connecting the plug to the lead and resting the metal hex of the spark plug on the metal part of the engine but this is not always as easy as it seems as many engines have plastic shrouds and other obstacles in the way. My method of testing for lack of fuel is to spray a shot of carburetor cleaner directly into the carburetor (air filter removed) and try to start the engine. If the engine starts and runs for a second or two and then dies you most likely have a fuel delivery problem.

Perform the necessary tests, report back with your findings and you will receive further advice based on your answers.

Lawnranger said:

which can be made from an old, working spark plug by clipping off the side electrode,

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Just curious, but why would you clip off the side electrode? It seems like that would create "much" more of a gap that perhaps, "some" coils wouldn't be able to arc across.

kenhafford said:

I have a 2005 scag tiger cub 48 after mowing for half hr or so the mower stall as if out of gas,I cleaned tanks,replaced fuel pump and filters new caps,I also replaced seat switch,fuse holders,cleaned battery terminals,runs fine when running,just keeps stalling.

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I've got a 26 hp Kaw that does the same thing. It's the coil.

chance123 said:

Just curious, but why would you clip off the side electrode? It seems like that would create "much" more of a gap that perhaps, "some" coils wouldn't be able to arc across.

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By clipping the side electrode on a used spark plug you can make a homemade spark checker. If the coil is good it should be able to produce a spark with high enough voltage to jump the new larger gap created by clipping the side electrode. This is a cheap, or free, alternative to buying a dedicated spark checker for those who don't want to invest in a tool that will be seldom used. Most people who attempt to fix their own mower change the spark plug and usually have a spare, used plug laying around and that is why I recommend that method. Since I work on a lot of small engines I have several dedicated spark checkers for coils up to 100KV. I have looked at the different spark checkers I own and noticed that the gap from the center electrode to the side is larger than the gap created by clipping off the side electrode on a regular spark plug so the method of making a homemade checker should not create a problem that "some" coils wouldn't be able to arc across and if they can't jump that gap then the coil is probably weak and the source of the problem. YMMV

Lawnranger said:

By clipping the side electrode on a used spark plug you can make a homemade spark checker. If the coil is good it should be able to produce a spark with high enough voltage to jump the new larger gap created by clipping the side electrode. This is a cheap, or free, alternative to buying a dedicated spark checker for those who don't want to invest in a tool that will be seldom used. Most people who attempt to fix their own mower change the spark plug and usually have a spare, used plug laying around and that is why I recommend that method. Since I work on a lot of small engines I have several dedicated spark checkers for coils up to 100KV. I have looked at the different spark checkers I own and noticed that the gap from the center electrode to the side is larger than the gap created by clipping off the side electrode on a regular spark plug so the method of making a homemade checker should not create a problem that "some" coils wouldn't be able to arc across and if they can't jump that gap then the coil is probably weak and the source of the problem. YMMV

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I just went out and did this.
Thank you now I have a spark tester

Sent from my iPhone using LMF

Carscw said:

I just went out and did this.
Thank you now I have a spark tester

Sent from my iPhone using LMF

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Simple, huh?