Funny thing happened on the way to the spark plug

[Macwrench 133]

Today I finally got to wrench on one of my two tractors for the first time since purchase.  The PO had installed a standard SPST toggle switch to the LOAD side of the starter solenoid to bypass it, so I suspected it bad.  Turns out it tested ok.  So I pulled the ignition switch and found the connections really corroded, especially the power blade which obviously has gotten hot before.  So it tested ok after cleaning, and I reinstalled it.  (it really needs to be replaced)  Cleaned up everything, installed a new battery hoping for magic... and ... nothing.

 

Looking around, I found the main fuse blown.  I put a new fuse in it, and I got SOME magic!  All the lights work on the dash, they test, but the start solenoid still didn't engage.

 

Figuring I'd bypass it just to see if the motor fired off, I pulled the spark plug out to clean and check it .. when suddenly... THE STARTER ENGAGED AND BEGIN SPINNING THE MOTOR!!!

 

Ignition switch is turned off.  I freak out and grabbed the main fuse and pulled it... it stopped!  The next hour was with a wiring diagram where I isolated a place behind the ignition switch where the red had melted into the tan wire.

 

Long story short, it runs with a prime, but no fuel going to carb.  Probably the pump.  I'll keep you posted after I put on clean pants!!!

[oliver2-44 10,824]

Good to hear another horse is on its way to coming back to life in Texas.  

Before you chunk the pump go through the fuel system piece by piece.

Disconnect the hose from the carb and crank it to see if your getting fuel there? 

If not, disconnect the hose from the pump and see if your getting gas to pump.  The hose or the fine mesh strainer in the bottom of the tank fuel shut off valve could be plugged. 

When you have fuel flow there reconnect to pump and disconnect pump outlet hose and see if you get fuel out of pump when you crank it. (My C81 had been sitting several years and the pump was gummed up with ethanol crystals.  I disassembled, cleaned and reassembled it and it worked perfectly.       

[ZXT 2,401]

I assume the tan wire is the starter solenoid wire? If the solenoid wire melted into the hot battery lead and it cranked, then that sounds like the ignition switch actually is bad.. Are any of the safety switches bypassed? It really shouldn't have cranked regardless.

[Macwrench 133]

1 hour ago, oliver2-44 said:

 (My C81 had been sitting several years and the pump was gummed up with ethanol crystals.  I disassembled, cleaned and reassembled it and it worked perfectly.       

That's a thought.  But when I break open these fuel lines they will all have to be replaced anyway.  They are hard as stone.

[Macwrench 133]

1 hour ago, ZXT said:

I assume the tan wire is the starter solenoid wire? If the solenoid wire melted into the hot battery lead and it cranked, then that sounds like the ignition switch actually is bad.. Are any of the safety switches bypassed? It really shouldn't have cranked regardless.

Seat switch is bypassed, but all others check on the indicator lights so I think they are still active.  The switch does need replacing for corrosion and wear, but it functions normal. 

[pacer 3,177]

Your description of the mess with the BBQ at the ign sw is all too common on our horses, an indirect result of the way the amp gauge is wired. Many of us go to a simple volt meter for this reason. I know that after about the 5th time I had a bonfire at the sw and melted wires I sure started using voltmeters.

 

Re the ign switch, OReilly's carries them, something like 12-14$ (other auto parts do too I think)

 

 

[Macwrench 133]

12 minutes ago, pacer said:

Re the ign switch, OReilly's carries them, something like 12-14$ (other auto parts do too I think)

 

 

Yep, shopping now.  I usually do Amazon, but if there is a vendor that we can support here I'll use them.  Norm at isave tractors.com is carrying them as well.

[ebinmaine 73,362]

5 hours ago, pacer said:

Your description of the mess with the BBQ at the ign sw is all too common on our horses, an indirect result of the way the amp gauge is wired. Many of us go to a simple volt meter for this reason. I know that after about the 5th time I had a bonfire at the sw and melted wires I sure started using voltmeters.

 

 

 

I'll second the voltmeter.

None of our tractors have ammeters.

 

[953 nut 60,701]

If some of your wires have already emitted magic smoke and there are corroded connections you may want to consider doing a complete rewire. In the long run you will save time and aggravation. Your connections can be renewed with some Delphi Packard GM 56 male and female connectors where needed.

 

[Macwrench 133]

8 hours ago, 953 nut said:

If some of your wires have already emitted magic smoke and there are corroded connections you may want to consider doing a complete rewire. In the long run you will save time and aggravation. Your connections can be renewed with some Delphi Packard GM 56 male and female connectors where needed.

True.  But I think I've found the worst of it.  All of these circuits are low draw, thus the relays.  They should only draw 0.5-1.0 amps.  The fuse is just to protect wiring, and I bet if it would have had the 25 AGC instead of the 30 AGC fuse, it wouldn't have melted.  The highest draw in the system is the headlights and tail lights, and I may just put LED's in there just for kicks.

[953 nut 60,701]

If you don't fix it right while it in the shop it will give you the opportunity to get some extra exercise pushing it back to the shop to repair those things that seemed unimportant.

[Macwrench 133]

16 hours ago, 953 nut said:

If you don't fix it right while it in the shop it will give you the opportunity to get some extra exercise pushing it back to the shop to repair those things that seemed unimportant.

 

 

Parkinson's law is the adage that "work expands so as to fill the time available for its completion".

 

In other words, as long as you throw time at it you will find things to fix.  At some point you have to call something done and move on.  Believe me, I'm in Aviation and I know all about Murphy's Law.