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Briggs 14.5hp

8K views 31 replies 6 participants last post by  suspicionofignorance 
#1 ·
A guy brought me his mower because it would not start. I started checking and he has bypassed all of the safety switches, everything is sodered and good. I checked for spark and it will not spark when you are holding the key in the start position, but when you relase it the plug will fire two or three times. I am hoping someone can give me ideas on what I need to check for next. I am at a loss and his yard is growing out of control. Hoping I can help a neighbor out. Thanks in advance.
 
#2 ·
So, it is not firing in the "start" position, but is in the "run" position? Do you have a volt/multi meter to troubleshoot with? Could be as simple as the switch. Although it sounds like some liberties were taken with the wiring system, so..........:dunno:
 
#3 ·
Yes I have a multi meter, don't get to technical on me as I am not a mower repair guy jut the neighbor. I dug a little deeper and found the only switch he bypassed was the PTO switch. I am not a mower repair guy so give me a break and don't get to technical on me. I can only see the plug firing when you release the key from the start position.
 
#4 ·
OK, back in from the garage. The only safety switch that was hard wired was the PTO switch. I rewired the PTO safety switch and still having the same results(firing when you release the key). I was told to unhook the mag ground kill wire. Where do I find this mag ground kill wire? I have to try something and I am really grasping at straws.
 
#7 ·
Dejavu...Recall I had a Toro hxl do that...the briggs engines will have a single thinner black wire leading up under the top shroud...that's the ign kill...If disconnected...you will have No safety at all...Believe these Toro's use a inline 12v relay to 'pull OFF' the ground while cranking and running...if relay does not get 12v , it will keep the kill wire grounded, and prevent spark...You may see a small circuit board with 3 relays..Troubleshooting can get more involved, with this design...Good luck..Hopefully you can merely disconnect the kill wire, verify fix, and find a way to re do it..
 
#10 ·
Okay, going to get after it once the sunlight gets up a bit. Got a reply from another site that said make sure the oil is filled correctly as there is a low oil switch and also to check the battery negative is making good contact. So going to have a bite to eat and then hit all of the above and hope I discover the problm. Thanks for all the help so far. I will keep you posted.
 
#11 ·
Well that did not take long. Cleaned the negative ground wire and contact point. No spark. Found and traced the small black wire from the Armaeture, it went under the engine and then was connected (soldered) to a YELLOW wire going to the ignition key. Which the wiring diagam show it as part of the OFF function. Cut the wire and grounded the spark plug and got great spark with the key in start position. Reattach black to yellow and had no spark, until I released the key from the start position then I got two or three sparks.
So a new question. Where should the armeture wire be connected/ I did not dsee any lose or ends of wires laying around.
 
#27 ·
It should be connected to the ingition switch so you can turn the thing off.
Some clot has connected wires willy nilly toi the back of the ignition switch so you will need to pull it out and check which ones are connected in each of the different key positions.
Then go back to that diagram and work out which wire is what
 
#16 ·
Could you post the model number of the tractor? I have had a few of them and might have the manual?
 
#19 ·
The first site showed me nothing on where this wire should be hooked up. The murray diagram I have printed and it doesn't show where the mag wire I supposed to be hooked up either. That is the problem I am having. I cannot find anything that shows where it should be hooked up.
 
#26 ·
The magneto wire goes to the ignition switch so it can turn the engine off.
If you take the switch out you will most likely see the terminals marked.
B = battery
M = magneto
G = ground
L = lights
S = starter
A = alternator.

If not then you will, have to test the switch.
Only 1 pair of terminals will be connectede when the switch is turned off.
One of these goes to gound and the other goes to the magneto. M & G
I seem to recall you being told the same information some where else.

In the start position again only 2 terminals will be connected, the B & S

And the only armature on your engine is in the starter motor.
You have a stator under the flywheel and an Ignition module outside the flywheel usually incorperated into the coil.

The ignition swich should not have 2 of the same colour wires attached to it .
I will assume the 2 yellows are the result of some blitering idiot attempting to bypass the safety switches without any idea of what he was doing.
 
#20 ·
I have no experience on Murray tractors...But the schematic that 5points post ref to does show TWO yellow wires...one should be parallel with a blue and plugged into what I assume is the black coil wire...However, you mentioned yours was soldered...Is it possible its incorrectly soldered to the yellow wire from the seat switch, which is grounded..? If not, you'll prob need to do some ohmmeter [continuity checks] at your key switch plug...the schematic shows the legend of connections performed by switch,
believe you will want to assure the yellow wire does not get grounded when in "start"..
- list# - PartsAndService - View Illustrated Parts Catalogues - ipl.cgi.v305 1 -
 
#22 ·
I looked and I have a couple of Murray manuals, but not yours. In mine the terminal M is your kill and is wired in yellow on my Yard-King version of a Murray. I can look at my other Murrays in stock today to verify color of kill wire.
 
#24 ·
Sorry Tim, looks like mine use the yellow for the kill of magneto! Wish I could help more!
 
#25 · (Edited)
Two yellows....one for key switch..one for seat safety, is what I recall seeing...and what I thought I had outlined in my post...If it were mine, I would NOT start hooking the kill wire up randomly to terminals on switch...12v dc applied to the coil kill lead can render the coil dead...or cause some unusual firings from internal circuit damage..[perhaps what you may be witnessing]..understandable mistake, as many owners , thinking of their car ignition systems, feel they must wire up the 12v to the coil...Don't do it..IMO.
 
#28 ·
All recent posts are good advice...However, I would still try to disconnect or cut the magneto kill wire first...and see if plug will spark in the run position....Just to prove someone hasn't also damaged the magneto...I still believe the diagram showed two 'separate" yellow wires used...wondering if the seat yellow was mistakenly tied to the coil..? Basically what I posted earlier...
 
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