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The Home Smithy
The Home Smithy, Small Engine Tech
Category: Small Engine
Satisfied Customers: 9619
Experience:  Small engine tech
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Hello, I have a 2001 Walker Lawn Mower (mtghs model) with

Resolved Question:

Hello, I have a 2001 Walker Lawn Mower (mtghs model) with a (20hp CH 20 kohler engine). Had a few shorts in the wiring harnesses so myself and an employee replaced ALL wiring harnesses and purchased a very good used engine. Mower has spark(test it), put in new plugs, flushed out gas and installed new, disconnected 3 safety switches and placed wiring inside connections so this would not prevent motor from starting. After all this mower started and ran for 5 minutes and then not again. MOwer also has good compression as I did a test on it. Also sprayed starter fluid into carb and into cylinder. Replaqced plugs again just for kicks but nothing. Dis-connected the fuel line running to carb and cranked so gas is flowing through. does not start even when I jump it by touching two screws on the starter. Also, key start will not work at all.
Submitted: 8 years ago.
Category: Small Engine
Expert:  The Home Smithy replied 8 years ago.

Hi Customer;

If the plugs are new and you squirt starter fluid into carb and it still will not fire then you have a spark problem. Pull the plugs and recheck that you have a nice bright whitish blue spark. If it is an orange spark then you have a weak spark and it might just not be strong enough to set off the explosion. the coil, or the amount of voltage going to it, would be suspect in that case. Make sure that when cranking the coil is getting a full 12+ volts. Anything less than 8 volts is insufficient. Once the motor fires it can maintain on 8 volts.

As for the key not working it is a matter of hooking the right wires to the right terminls. For this you will need to determin which connection goes to where. You should have Off, on/run, start, common 12v+, and it should have negative continuity to the chassis.

Please see drawing for wiring information.

graphic

 

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Customer: replied 8 years ago.
The mower has a healthy spark as I inserted a a tool between the spark plug cap and the top of the plug and when cranking engine the brightness of light was exactly the same as my other identical mower. I have the entire schematic, however this mower is not quite that simple. My employee/mechanic pulled the engine out of the mower and actually got it started, but when back inside the mower and all wires are connected it will not.
Expert:  The Home Smithy replied 8 years ago.

Ok the only thing that might be screwing things up would be a capacitor discharge ignition firing at the wrong time. If the unit doesnt have a CDI ignition then you need to look at the fuel system better. If the unit bench fires ok then the common denominator between the two setups has to be the problem.

Try setting the motor up just like he did when he bench tested it, but in the frame. Then start to change the systems over to the tractor system one at a time until it fails to start. That will be where your problem lies.

 

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Customer: replied 8 years ago.
My employee had gotten the unit running, however he did so by bypassing some of the wiring by running additional wires. Also,t there were additional electrical parts that were replaced, so it was a combination of the two.
Expert:  The Home Smithy replied 8 years ago.

Ok, so you have it running then?

If he installed new wiring then it should be easy to determin the existing wire that is defective by doing a simple continuity (or lak thereof) and pinpoint the bad point in the wiring or the componant that has failed. If the failed componant is a safety feature then I strongly recommend that it be properly repaired and not just bypassed. There are reasons that these safety features are in polace. Ususly because someone at some point has been injured or killed.

Safety is something that should NEVER be bypassed.

 

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