No spark 770

dustywing

New User
Replaced the points with a Pertronix device (I guess it's a solid state or some kind of electronic).
The tractor ran for a while (not even 40hours) and just quit.
Now there is no spark.
If you position the rotor in the No. 1 position and turn it back and forth you can hear a click from
Petronix.
The rotor rotates, I can't seem to find the timing mark to be sure the No.1 piston is in the correct position.
I was trying to figure out how and where the rotor is driven, if it would be possible for the timing chain to have broke and the rotor still rotate?

Seem every time we fix one thing it's another, I should clarify have it fixed at a shop.
 
If it was running, your problem is electrical. Take nothing apart, it won't change unless someone moves it. Time for the VOM meter
 

first, there is no timing chain in the 770 engine so u can rule that out, you say the module clicks when you move the magnet ring at the tdc position, the next step would be to use a test light at the coil neg or - terminal, when you turn the shaft and the magnet ring and you hear that click the negative post on the coil should get hot, the test light should flash. i have never heard those modules make a noise but have never tried what you described. are you sure you are not gearing a spark jump somewhere?

i use pertronix in my engines an have installed many over the years and have only lost one or two but they are man made so subject to failure, the main reason for failure on a 4 cyl engine is failure to read and follow the installation instructions concerning the installation of the ballast resistor. look at the instructions carefully.

pertronix is good about warranty so if faulty you should be taken care of, if in doubt it would be simple to sub the points bak in and try it,

one 770 did exactly as yours, look at the tip of the rotor and see if there is a burn mark out over the right hand side of the rotor nose tip, the one i did have that issue with the module was positioned in the wrong spot causing the spark to fire way out of phase with the rotor to cap contact alignment, easy way to check that is sub in a new rotor and see if it starts.
 
Yes, and that probably shouldn't change. Is it being switched? The module opens and closes the primary ignition circuit just like your breaker points. 2 advantages of it. It does it much quicker than a mechanical switch that arcs thus collapsing the primary magnetic field in the coil. The quicker the collapse, the higher the voltage induced in the secondary. The second adavantage is no moving parts, so adjustment doesn't change, once properly set up, thus wear is not an issue. Voltage spikes/surges etc can fry the internals, but they are rare. A ballast resister is used in all 12v systems with breaker points to limit current across the switch, thus extending life. Most solid states do not utilize resistors, but I'm not sure of your unit. Your instructions will tell you if you should and shouldn't have it in the circuit. Resistors can be a seperate resistive unit, a special reistor wire or built in the primary circuit internal in your coil.
 
What confuses me is that it ran and the stopped dead.
Can someone tell me where the timing mark is?
I don't want to spend money on a manual now, after the fixes and cost I'm in over 7K. If I can't figure the issue out to the bone yard and cut my losses. Wish it were an old IH cub or early Fordson
I could make a garden around.
 

When you hold the coil wire close to the block and turn it over does the coil wire have spark coming out of the coil?

Believe me, I have been through this with a 770 just like you describe, run some hours, quit, Try what I ask before you get to discouraged. We need some answers. Get back to us, don't make it more complicated than need be. Send your phone number to [email protected], I'll call you.
 
I think you have a generator/alternator problem and you aren't getting full charge voltage out of it. Petronix takes a good battery with full 12+ volts to start and run (I know this because??). Breaker points systems are more forgiving, especially during starting. If your battery is too small (Cold crank amp wise) and or old and on its last legs or you have wiring problems Petronix can baffle the fool out of you. Like Mel says, I love mine now that I have a new, good battery but before that the Petronics electronic ignition was problematic.

The Petronics ignition just converts your old distributor with points to the electronic ignition systems that autos adopted back in the mid 70s.

Jim
 
I have saved your email in case I need one on one, I surly appreciate the time you have taken.
I am going to try a new rotor supposed to be in tomorrow.
We'll see haw that works. Also charging the battery to mkae sure there is a full charge.
Again thank you
 

please drop your number to my e mail, i will call you and explain exactly what to look for to see if the issue is the same as my 770 experience and what to look for on the rotor, it is very visible. If I am correct then Pertronix will have to make it right by you. I had to send my distributor out to them and they moved the module to a different location on the plate.
 
We got a new rotor and holding the coil wire to the clean freeze plug it will only spark once.
Every time you turn the key it sparks just once.
 


If you have good voltage to the module I suspect you do have a bad module, when you get the distributor set so you can turn the shaft and hear the sound you heard does it spark then, if you have a test light the negative(black water at the coil) should flash brightly when you turn the rotor shaft. if it flashes every time you rock it back and forth I would try another coil. Let me know what happens, this is a different issue than I had but should be able to figure it out.
 

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