Bad gauges on '89 520

[three50seven 2]

My uncle has a 1989 520H that has two gauges that aren't working properly. When the tractor is in neutral and throttled up, the vacuum gauge reads 0 and the tach is pegged out. I don't think it is an engine problem, because the tractor runs and functions perfectly. Any ideas?

[Ed Kennell 35,873]

The vacuum gages tube connection is usually broken on the back of the gage or the tube is not connected at the gage and the carb.
The tach and other electrical problems on the 520 are usually caused by poor corroded connectors.    
Go to the manuals section and print out the manual for your tractor.   Try cleaning the three tabs and connectors on the back of the tach. The tach trigger wire goes to the double tab on the regulator. Make sure  it  is cleaned and connected.

BTW,    TO   

[gwest_ca-(File Mod) 10,505]

Wiring diagrams
http://www.wheelhorseforum.com/files/file/4395-tractor-1989-520-h-wiring-detailed-492-4509pdf/

Garry

[three50seven 2]

Thanks for the help guys, I will see what I can do!

[cleat 4,988]

It's not really at 4000 is it ?
The Onan will easily do that if the governor is not set up properly.

Cleat

[three50seven 2]

No, there's no way it was running at 4000 rpm. It was throttled up, but the tach doesn't drop back to 0 when it's shut off either.

[cleat 4,988]

The tach's are air core and will go to any random place when shut off.
However, when you turn the key on it should go to zero.
On one of my 520's, the tach suddenly stopped reading and stayed on zero. The problem in that case was the charge fuse had blown (on mine that one was down by the starter).

Try taking all the wires off of the tach and cleaning everything up as well, may be a bad connection. Also verify the connection of the wires at the voltage regulator.

Cleat