I am in need of an electrical diagram for a Briggs and Stratton Vanguard 20hp engine. Model # is 351777. It stopped just like I turned it off, and I have already electrically checked all of the wiring/switches on the mower, isolating the problem to the engine itself.

Josh, August 2010

I removed the grounds from the coils and nothing changed. I find it hard to believe that I lost both of them at once.

I now believe my anti-afterfire solenoid went out. Testing in place, it seems to do nothing, no clicks, etc. I will be pulling it tomorrow to do a proper bench test.

In my search for more information, I found a great electrical diagram in "B&S Customer Education, Engine Alternator Replacement Guide" It is a PDF, and can be found at http://www.google.com/url?sa=t&source=web&cd=6&ved=0CCwQFjAF&url=http%3A%2F%2Fwww4.briggsandstratton.com%2Fmiscpdfs%2FRNT%2Falternator_replacement.pdf&ei=usBtTJWmJMOC8gb_h_XkCw&usg=AFQjCNESLLgE6aln2zyf7DnyoTbQREFj3g

~Josh, August 2010

Remove the shroud, exposing the ignition coils. Disconnect the spade terminals from the coils. Attempt to start the engine. If it starts, you have a chafed/shorted stop wire. If not, you have duff coils (possible if the engine has overheated - they cook). If it DOES start, you'll need to choke it off to stop it.

phil_saunders(a)bigfoot.com

Phil Saunders, August 2010