520H starting issue - PTO safety switch?

[Wheelhorse4me 4]

I purchased a 520H last night.  Sometimes it starts easily.  Sometimes it will not start, but it turns over.  The prior owner suggests giggling the PTO lever to see if that helps.  Is there a safety switch that is needing replacement?

[gwest_ca-(File Mod) 11,545]

Have a tractor model number and serial number off the rear fender pan? With that we can link you to the correct wiring diagrams.

[Handy Don 14,203]

3 hours ago, Wheelhorse4me said:

I purchased a 520H last night.  Sometimes it starts easily.  Sometimes it will not start, but it turns over.  The prior owner suggests giggling the PTO lever to see if that helps.  Is there a safety switch that is needing replacement?

The 520-H’s have more than one safety switch that can affect start/run. For most models leaving the factory, there were two on the PTO, one on the seat, and one on the motion control. There are also fuses.  

That said, your machine has seen a lot of years since new and at some point in its life an owner may have altered the wiring or there may be some other age/wear issue with the wiring. 

Once you have the model & serial we can direct you to the manuals and wiring diagram and we’ll be glad to help you run down the gremlin. 

Edited June 6 by Handy Don

[953 nut 60,541]

23 hours ago, Wheelhorse4me said:

Sometimes it starts easily.  Sometimes it will not start, but it turns over.  The prior owner suggests giggling the PTO lever to see if that helps

Pardon my being blunt about this but pervious owners say a lot of things that must be taken with a grain of salt. 

The fact that it sometimes starts easily rules out the safety switches in my opinion. The PTO switch prevents the start relay from allowing the engine to turn over if the PTO is in the wrong position. The seat switch is in line with the Kill Relay that would interrupt the ignition if you were not on the seat. Take a look at the wiring going to the seat switch, could be a pinched wire that sometimes isn't making a connection. Please avoid the temptation to pull out all of the safety switches and their wiring, they are seldom the problem.

Have you checked to see if there is spark when it refuses to start? The fuel tank is below the seat and the carburetor is above the engine so there could be a fuel delivery issue. 

Can you give us a bit of clarification as to when it just turns over but won't star?  Has it been sitting for a day or longer?   Has it been running, you turn it off and a few minutes later it turns over without starting?

We are here to help but need a few more details.

[Wheelhorse4me 4]

Richard,

First, thank you for your service to our country.

I don't mind your bluntness and you are right, the seller can say whatever he wants.  The tractor, and the problem, are mine now.  I'm ok with it - I'll restore this 520H and make it last the rest of my lifetime.

The seat switch on this tractor has been removed.  The prior owner installed an aftermarket seat without a switch.  This is something I will rectify sooner than later.

The tractor ran.  Started it at the sellers place then test drove it around a bit.  Turned it off, then started it again and drove it onto my trailer.  When I got home, it would not start.

I have a huge job today that will keep me busy, but I will check for spark tomorrow.

 

Thanks again,

 

Erik

[lynnmor 7,886]

Download the Demystification Guide, it will break down each system and be a big help in troubleshooting electrical issues.

[953 nut 60,541]

57 minutes ago, Wheelhorse4me said:

Turned it off, then started it again and drove it onto my trailer.  When I got home, it would not start.

Sometimes a trailer ride will shake something loose in the fuel tank or an electrical wire could have come loose. With the seat switch having been bypassed the Kill Relay will be powered allowing ignition power any time the key switch is in RUN or START so that eliminates one probable suspect.

[Lee1977 7,235]

If they have not been kept clean Onan draw in a lot of dirt and grass. My 520 was 30 years old when I got ,I cleaned half a bushel dirt and grass out from under the engine covers, under the hood stand and off the hydro. 

Found a lot or rust on the safety switches , I replaced all four of them and the key switch also added an electric fuel pump before I got it easy to start.

[nylyon-(Admin) 8,083]

One thing to check is the 9-pin connector.  This failed on my 416-8, in my case it caused a complete loss of electric power, but it could create other issues I would imagine.  Something to check, and replace if needed.