Murray Mower Repower

[Maknwine]

I've had a project waiting under the barn and getting to it now. Tecumseh 13hp exploded years ago. Recently picked up a 15.5hp Briggs for $100 off craigslist. Its bolted up with belts on and will work out the muffler issues later. Murray's electrical wiring still intact and have the wiring schematic so I understand the wiring there. I have a yellow wire single connector in pic that schematic says is magneto gd. I'm almost thinking this goes to the black wire coming out of motor. The DC output and ac wiring connectors matched up so I think those are correct.

The old Tecumseh did not have the carb solenoid wiring so I have to do something with those. Looks like one wire from it goes to ground and the other gray wire would get wired into the switch somewhere to go to the "off" position.

Hopefully this thread gets some smarter guys than myself to weigh in.

Tks
Tom

 

[oldnslo]

Was the old Tecumseh a points and confessor ignition system or an electronic ignition system? Magneto and sounds like the ignition shut off circuit.

Do you have the wing diagram for briggs?

 

[Spanner]

In the Pics 4 & 5, The 4-wire connector is for the machine whatever that B&S engine came off.

The Grey wire will be +12V feed to the carb solenoid. (Yes, you need to power this from the key-switch in the 'Run' position.

The Black wire will be 'magneto' Ground or "Stop Engine".

The Yellow and White wires in the 2-wire connector maybe pick up output feed from the Alternator and put it to the Regulator/Rectifier. Edit: But your engine has the 'unregulated' alternator output with a simple diode rectification seen as the bulge in the Red wire near the dip-stick tube.
So you can probably ignore these two wires in the 4-wire plug.

The Black wire in Pic 2 with the uninsulated ring terminal should be grounded to a handy screw on the throttle control plate that has a 5/16" head.

I'm just going to re-check the pics for the 2-wire and will edit this shortly. (Edited)

Also, you might like to check the starter motor for why it has tape around the base?

(Could also have cleaned the motor before fitting it to your clean chassis.)

 

[Maknwine]

Was the old Tecumseh a points and confessor ignition system or an electronic ignition system? Magneto and sounds like the ignition shut off circuit.

Do you have the wing diagram for briggs?

I haven't found the exact wiring diagram for the briggs.

 

[Maknwine]

In the Pics 4 & 5, The 4-wire connector is for the machine whatever that B&S engine came off.

The Grey wire will be +12V feed to the carb solenoid. (Yes, you need to power this from the key-switch in the 'Run' position.

The Black wire will be 'magneto' Ground or "Stop Engine".

The Yellow and White wires in the 2-wire connector maybe pick up output feed from the Alternator and put it to the Regulator/Rectifier. Edit: But your engine has the 'unregulated' alternator output with a simple diode rectification seen as the bulge in the Red wire near the dip-stick tube.
So you can probably ignore these two wires in the 4-wire plug.

The Black wire in Pic 2 with the uninsulated ring terminal should be grounded to a handy screw on the throttle control plate that has a 5/16" head.

I'm just going to re-check the pics for the 2-wire and will edit this shortly. (Edited)

Also, you might like to check the starter motor for why it has tape around the base?

(Could also have cleaned the motor before fitting it to your clean chassis.)

Great, I hope to get back to this tomorrow night. thanks for the help.

 

[Maknwine]

Just looking at the wiring schematic, the "RUN" position on the switch has none referenced to the wiring hookup. So I'm unsure where to run that grey wire from the carb solenoid.

 

[Spanner]

Early ride-ons had a simple 2 or 3-pin switches and rope start. With the advent of electric start we moved to 4-pin switches and then 5-pins INDAK brand switches to allow for lights. The need for anti-afterfire solenoids on carburettors required the 6th pin found on most riders. For a time the 5-pin plug was used on 6-pin switches with an additional wire separate from the plug for the carb. Then 6-pin plugs were introduced to tidy the connectors.

Murray always seem to work outside the norms. Here we see them using the AC circuit to run the lights. That's ok. it works.

You have a 6-pin switch and a 5-pin plugged machine. I can't see where the Green wire (L Terminal) off the switch goes. (Parallel to the Red wire (M Terminal)for lights?)

Important to note that not all switches are 'wired' the same internally. They all 'look' the same externally. Beware!

The graphic seems to imply there is no switched circuit for just "Run" but "Run & Lights" has terminals X & L connected.

The Green wire on the M Terminal would appear to be a ground return for the lights and is probably earthed to the switch casing itself??

Where does this all leave you?

The 'usual' solution is to eliminate the solenoid one of two ways - Replace it with a basic (old-fashioned) bowl-nut OR remove the solenoid, cut off the plunger rod and reinstall the solenoid using it just as a dummy bowl-nut to hold the float bowl on.

Not very sophisticated i.e. Crude but effective.

The elegant solution would be to get a better switch for this application (One that is able to power the solenoid circuit in 'Run') and re-wire the machine to work with that switch.

 

[Maknwine]

Very informative, thanks for taking the time for that. Would another option be to wire the solenoid into the "run w/lights" pin? And just have daytime running lights....weird but maybe simpler...

Or how about just a toggle switch for the carb solenoid? Just tie into battery?

 

[Spanner]

No. As you will see from your schematics and I noted earlier, the lights are on the AC circuit. The Solenoid is a DC item.

A toggle switch is a better option (With an in-line fuse) and meets my suggestion of 're-wiring' the machine.

 

[Maknwine]

I see on YTube that people just cut off plunger like you said and then they install a manual inline fuel shut off valve. That is probably the cheapest/easiest route. The mower is probably not worth too much investment in dollars.