Craftsman ELS 725 won't start

vincep99

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I am helping my neighbor with his ELS 725. It has been sitting all summer (which adds to the challenge!), and here is what I did:
1. Charged the battery: it cranks fine
2. Verified it has spark
3. Installed new plugs
4. Verified (with my thumb, not a compression gauge) that is has compression
5. Drained the fuel, put in new fuel
6. Changed the fuel filter

I noticed that while the old filter had some old fuel left in in, the new filter would not fill with fuel. Indicates the fuel pump is bad? I ordered a new one to be on the safe side

Regardless of the fuel, I sprayed ether into one cylinder (then replaced the plug of course) and don't get any firing. Indicated something else afoot.

I can get the model# and serial number if needed.

Any ideas where to look next?
 

bertsmobile1

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Fuel filters do not fill all the way because of the way they are made,
If you want it to fill completely then fit it backwards at avoid the air pocket.
They work exactly the same in both directions except any junk will be inside the paper element so you can not see who dirty it is.
To test the pump remove the outlet tube at the carburettor , put it in a catch can of some sort then crank the engine .

If you can not get the engine to fire by spraying starting fluid ( or fuel ) directly into the cylinder then the valves or timing is the culprit.
Thumb test does not really cut the mustard any more unless you are a shaved ape making You Tube videos to amuse the monkeys.

Remove the rocker covers and watch the rockers going in & out as you rotate the engine.
Note how far they move and when they move with respect to the position of the piston.
Also make sure they are the same distance from the bottom of the head.
Both valves are the same length so they should sit the same distance out when closed.

If they check out OK the pull the flywheel off and check the key if it is broken them the spark will happen at the wrong time
 

vincep99

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bertsmobile,
Thanks for the rapid and detailed reply!

I will do exactly as you said; also I will get out my compression tester to verify the compression
 

bertsmobile1

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bertsmobile,
Thanks for the rapid and detailed reply!

I will do exactly as you said; also I will get out my compression tester to verify the compression

Don't bother.
Most small 4 stroke engines use some form of decompression.
Thus the reading will depend upon the valve lash.
If you open out the valve lash to bypass the decompression then the starter won't be able to crank the engine past compression
Leak down testing is what small engine repair shops use
 

vincep99

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OK, thanks again! You are a wealth of knowledge.
 

vincep99

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bertsmobile1,
I removed the fuel pump outlet like you said, no output. I replaced the fuel pump, gave it another shot of ether, and it started!

Ran pretty rough, which was to be expected, but it surged even when warmed up. Since it was sitting all summer, I figured the carb needed to be cleaned. Pulled the engine shroud and found a huge mouse nest. Cleaned that up, pulled the carb/manifold, and as suspected the fuel bowl was stained from ethanol/moisture.

Cleaned it all up, sprayed SeaFoam through the jets, blew them out with air, put it all back together. Runs like new.

Thanks again for all your help!
 

bertsmobile1

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bertsmobile1,
I removed the fuel pump outlet like you said, no output. I replaced the fuel pump, gave it another shot of ether, and it started!

Ran pretty rough, which was to be expected, but it surged even when warmed up. Since it was sitting all summer, I figured the carb needed to be cleaned. Pulled the engine shroud and found a huge mouse nest. Cleaned that up, pulled the carb/manifold, and as suspected the fuel bowl was stained from ethanol/moisture.

Cleaned it all up, sprayed SeaFoam through the jets, blew them out with air, put it all back together. Runs like new.

Thanks again for all your help!

Good to see you have got it running & thanks for the end post, most don't bother.

Next time you have the housing off carefully check the wires, mice tend to chew on them and if the magneto wires have any breaks in them they can short out to the engine which is how the engine is turned off.
 
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