8N starting problem

[Maury Ferrari]

I have a 49' w/front mount distributor and electronic
ignition.The tractor has been running great for over a year until
now). I have changed the coil, installed new plugs, new plug
wires,new rotor and cap, and I even replaced the distributor with
points I had as a spare (used, but it looks in good condition). I
get good sparks from the checker and the plugs. I get 12V at the
coil without the resistor and about 6V with the resistor in place.
I have also replaced the carburetor with a used spare and
installed new Intake/exaust manifold gaskets. Compression is
good and fuel appears to be getting into the cylinders. The
tractor is hard to start, and if it does, it runs for short time and
quit. Fuel is good.
Everything seems to pointing toward the distributor, but before I
invest $200, I need a word of wisdom from someone that knows
more than I do. Please help!
Maury

 

[Bruce (VA)]

If you still have the points in it, this might help.

As a good rule of thumb, a 1 - 2 minute run times is usually the condenser, ballast resistor, or vacuum lock....or, failure to turn the gas on. A 5 minute run time is usually fuel screens. A 15 minute run time is usually the ignition switch. A one hour run time & then restarts after it cools down is usually the coil. Next time it does this, check quickly for spark then fuel. By quickly, I mean as soon as it stops.....not 5 minutes later. Then, get rid of the spark tester. Make your own. Get an old plug, open the gap to 3/16, ground it to a rust & paint free spot on the head, turn the key on & crank the engine. You have three possibilities: no spark, weak and/or intermittent yellow spark, or a bright blue spark. What is it? Next, check for fuel. Remove the bolt in the bottom of the carb; as long as the fuel is turned on, you should see gas flowing out of the carb.

Check back w/ the results of these tests & you will get lots of help if it doesn't run.
50 Tips

 

[JMOR]

Hope you get a chuckle outa the 'toon, Bruce (VA).

 

[JimSC]

Good one, JMOR. Kinda reminds me of me...

 

[C.bailey]

It's possible, but rare, that the coil is heating up then failing. Once it quits do you still have good spark?

 

[C.bailey]

Been there burned that! LOL

 

[Bruce (VA)]

Good one! LMAO!

 

[Phil (NJ,Az,Sask)]

(quoted from post at 11:41:43 08/18/07) I have a 49' w/front mount distributor and electronic
ignition.. I get 12V at the coil without the resistor and about 6V with the resistor in place.[/qwuote]

The 6 volt reading is not normal for any Front Mount coil. The proper current for all Front mounts is 3 amps MAX

If you are using an OEM 6 volt coil the voltage MUST be ~3 Volts
Current in your case (6V divided by 1 ohm) = 6 amps)


If you are using the 12 Coil the Voltage will be > 8.5 volts, this is best obtained by using the OEM Ballast (only)
Current in your case (6V divided by 2.8 = 2.14 Amps)

I suspect you are using the Wrong Resistor for the Coil, in one case (OEM 6V) you will burn out the coil, and the other (12V) you coil does not have enough current.

JMHO

 

[Maury Ferrari]

Thanks for the input, Phil. You are right, it looks like I have the
wrong resistor. Before I continue this troubleshooting I need to
order this ballast resistor. I am, however, a little confused on these
resistor assemblies. There is no indication wether they are for 12v
or 6v. Are they the same ohm value for both voltages?
Thanks
Maury

 

[Maury Ferrari]

Hi Bruce,
thanks for your valuable input and tips. After a short pause, my 8N troubleshooting continues. As I originally stated, the problem was hard starting and running a bit rough, and it still is. I am getting a nice strong blue 3/16" spark on all plugs (using the tester you suggested). I have new plugs with new wires and coil. Voltage to the coil is 8.5V after the resistor. After checking and rechecking the ignition area, I am inclined to believe that I am chasing the wrong goose. Case and point: It seems like this tractor is running on one cylinder. While running, I remove #2, 3 and 4 plug wires and does not miss a beat. Then I take #1 out with all the other three in place and the engine stops. Also, I try to put it in gear and, of course, does not have any power to continue. All cylinders have good even compression (around 150 PSI) and the tractor does not smoke/or use oil.
With that in mind, is my next step to take the head for a visit to a machine shop? Or is there some quick checks I can do before taking this step?
All inputs will be appreciated. Thanks.

Maury

 

[Sean (TX)]

Recheck your plug wires!! Firing order is 1-2-4-3 Sounds like you crossed the wires..