I Need Help!!!

[super99]

I'm stymied. I have a 77 gas and can't get fire to the plugs. It has been converted to 12 volts. I put a new 12 volt coil and resistor on it last summer. It has had new plug wires, cap and rotor in the last couple of years. I used it to replant some wet spots this spring , ran great for a 1/2 hour or so and then started missng. Got steadily worse and was barely able to pull itself to the house. I had new points and condensor and put them in, no fire. I checked wires with my simple light tester, and thought it was grounding out on the stud that goes thru the side of the distributor. Got a new one and put it on last evening, and still no fire. I put a tester in the plug wire, and nothing is getting to the plugs.I am going to file the old points and put them in and try it tonite. How can you tell if it's the cap, rotor, or plug wires without just replacing everything. The inside of the cap looks good and the terminals are clean, I used emery cloth on the end of the rotor. I'm lost, can someone lead out of this mess???? Thanks, Chris

 

[dave k1]

ignition switch

 

[Gary Spitznogle]

check for fire at the coil and that eliminates rotor cap and plug wires

 

[e]

I vote for an ignition switch issue, but usually that's a no go/go failure instead of causing a miss.

My honest opinion, take the coil, points, and condenser and throw them in the trash. Buy an MSD coil and a Pertronix electronic ignition kit. I used to be like you and spend hours screwing around chasing stupid issues. Every gasser that rolls onto the farm gets that treatment and knock on wood, it's been years since I've had to even change spark plugs. Stuff just runs and runs and runs. The quality of points and condensers has gone way down hill and I was having problems with "farm store" condensers not even making it an hour. Enough was enough.

 

[chucksoliver77]

i agree with E, i put an electronic ignition on my 77 25+ years ago, never fouls a plug, always starts and put new plugs in it every 5 years. if you do, use the recommended wires and plugs. chuck

 

[super99]

OK, I went back out, put the new points back in and set them at .020. I took my Harbor Freight In Line Spark Checker, removed coil wire from coil and inserted the metal end into the coil and pushed the 2 boots together and hit the starter button. LOTS of fire in spark checker. Then I moved to the distributor cap and did the same thing, again lots of fire. Put it on a plug wire and nothing. So, I'm guessing I will start with a new distributor cap and try that. I've thought about the pertronix change over, but this tractor doesn't get used much, not sure I want to spend that much on it. BUT if I get frazzled enough with it, I may. Chris

 

[chucksoliver77]

chris, is the rotor turning and is it down in the slot on the distributor shaft? chuck

 

[Anonymous-0]

have seen rotors burn thru and arc to dist. shaft

 

[tech cann]

i would take a ohm meter and check the Resistance in all the wires it will tell you if the wires. if the wire has a few broken stands in it. it will not let the power come. take the leads on the meter and put one in each end.

 

[larry from md.]

It could be the coil they can work for a while then start to miss.Try another if you have one.

 

[fullpull88]

Come on guys he told you the problem 12 volt coil and a resister? If ya got a 12 volt coil ya don't need a resister. Big Sal

 

[super99]

OK, now I'm confused. I have a JD 70, 12 volt system that has no resistor between coil and distributor. runs fine. I also have a Farmall 400, it has a resistor between the coil and the distributor, runs fine. The 77 was a 6 volt converted to 12 volt( before I bought it). I buy points and condensor for a 77. Do I need the resistor or not?? Should I be buying different points and condensor since it is now 12 volts?? Chris

 

[Anonymous-0]

Some coils have internal resister some do not,You need to know which one you have.

 

[Rob Mo.]

I recently did a 12-volt convertion on my super 77. Bought a new coil from the parts store & external resistor. After putting everything together, I would not fire. Same thing u have going on. With a volt/ohm meter, I checked that I had 12-volts going to the resistor, but 3-volts going to the coil. I was completely baffled. The only thing that I could think of, but couldn't believe is that I had a bad coil. Even new from the parts store, it was bad.

With a volt meter, check that u have 12-volts going to the coil & out the coil. Anything less, it will not have enough juice to light the spark plug.

 

[super99]

The coil on the 77 had a built in resistor when I bought it. It would run great for a few hours and then die, coil too hot to touch. When it cooled down, it would start and run fine until the coil got hot and it would die again. I bought another coil with internal resistor and replaced it, same thing. So I bought a new coil without a built in resistor for it, added an external resistor and that appeared to cure it. I've had the JD for over 20 years, the Farmall for about 10 years and no problems with either one. Still trying to figure out if I need a resistor or not. Chris

 

[larry from md.]

Yes you need a resister charge systems put out more than 12 volts, 13.6 to 14 volts and the resister is needed to hold down the voltage and increase the life of points,condenser and coil. Thats one big problem that happens if the charge system goes full charge all the time, the other parts overheat and go bad includeing the resister.