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Spark color?
Post by porkchop on Sept 17, 2006, 4:32pm
I still can't get my truck to start. It wants to go but just won't light off. I tested the spark and it was orange and sort of weak. All I have ever seen is blue, so what does it mean? Or am I just losing my mind.
Re: Spark color?
Post by luckypabst on Sept 17, 2006, 7:13pm
Could be weak battery or coil but I bet it's voltage drop from running the starter. Most stock wire harnesses have a way to bypass the ballast resistor/resistor wire during startup to increase voltage at the coil and produce a hotter spark.
How did you wire in the ignition circuit?
Chris
Re: Spark color?
Post by porkchop on Sept 17, 2006, 7:44pm
I used a voltage reducer for the coil. The stock coil wire goes to the reducer and then it goes to the coil. Maybe the reducer is to much.
Re: Spark color?
Post by luckypabst on Sept 17, 2006, 8:00pm
You should have a bypass wire, maybe from the starter solenoid or the "start" position of the ign switch that goes directly to the coil + and gives it full 12v only when you're starting the engine.
Chris
Re: Spark color?
Post by porkchop on Sept 17, 2006, 8:11pm
I am still running 24v. So I should run a bypass wire? Not really sure I understand that. I know I have a weak spark just need to figure out why.
Re: Spark color?
Post by luckypabst on Sept 17, 2006, 8:25pm
Oh, didn't know that. What's your voltage at the coil with the key on?
Is that resistor designed for 24v? If not, you could have some other problems that may or may not cause the weak spark.
Re: Spark color?
Post by kwai on Sept 17, 2006, 10:26pm
Try running run the coil off of one battery directly. This will eliminate the resistor as a problem until you get it running. The truck I just picked up has a 12 volt coil running off of 1 battery. Does fine.
Re: Spark color?
Post by luckypabst on Sept 17, 2006, 11:16pm
Concerning the coil - what I'd do if it were my truck:
Verify to full certainty that the coil is matched to the resistor. Each coil has a specific internal resistance that needs to be mated to the correct rated resistor to meet a total resistance value. There's more to it than just simply slapping any 'ol coil on there and away you go.
And yes, there are resistorless coils available as well. If your coil is anything close to new, it should have labeled whether it requires a resistor or not. If in doubt, one way to be certain is to purchase a new coil and resistor from the same application - my favorite was mid 60's Ford trucks since I knew they used the coil and resistor style ignition. A decent set should not be terribly expensive and would rule out any mis-match possibilities.
Then, as Kwai said, I'd take power off the first battery for 12 volts to the coil so you don't need any kind of voltage reducer. What sort of voltage reducer are you using? A ceramic resistor has a variable voltage drop, dependant on the amp draw of the ignition system - you'd have to run through an equation to figure the ideal ohm rating for the 15ish volt drop you need.
For the weak spark deal, I'd make certain the battery is fully charged, verify voltage at the coil, both "on" and with the engine cranking and make a routine check of your electrical connections.
Chris
Re: Spark color?
Post by porkchop on Sept 17, 2006, 11:36pm
I have a 3.0 ohm resistorless coil. With the engine cranking the coil voltage is 5.4. The voltage reducer is one I picked up at Napa. I will get the name brand later. I am thinking with the voltage reducer and the 3.0 ohm coil it is dropping the voltage to much. I hate electrical and not very good at it, so this is just a guess.
Re: Spark color?
Post by brute4c on Sept 18, 2006, 9:23am
Usually the bypass allows for the full voltage of a 12 volt system (I know you are running 24) to go to the coil when cranking and then drops it to 9 or 9.6 volts when running...5.4 in the cranking mode is WAY LOW and does indicate a very weak spark...less than half of what would normally be there in the start mode...
I would pull the resistor and hook to the one battery at least for testing...in the long run, I would run a voltage reducer...24 to 12 volt unit...which I believe you ordered a bit ago...
Re: Spark color?
Post by barrman on Sept 18, 2006, 9:36am
Do all the above stuff for the coil. If that doesn't work, go back to the basics. Points clean and proper gap? Condensor new? Besides the above wiring troubles, it sounds like the condesor is not right. You will chase that forever if it is it. Change your wiring and then look at the distributor.
Re: Spark color?
Post by porkchop on Sept 18, 2006, 10:19am
Quote: <TABLE class=bordercolor cellSpacing=1 width="90%"><TBODY><TR><TD width="100%"><TABLE class=quote cellSpacing=0 cellPadding=2 width="100%"><TBODY><TR><TD width="100%">Usually the bypass allows for the full voltage of a 12 volt system (I know you are running 24) to go to the coil when cranking and then drops it to 9 or 9.6 volts when running...5.4 in the cranking mode is WAY LOW and does indicate a very weak spark...less than half of what would normally be there in the start mode...
I would pull the resistor and hook to the one battery at least for testing...in the long run, I would run a voltage reducer...24 to 12 volt unit...which I believe you ordered a bit ago...</TD></TR></TBODY></TABLE></TD></TR></TBODY></TABLE>
Jon, I do not have a resistor, as stated above I am running a resistorless coil. I am also using a voltage reducer from 24 to 12.
Tim, I looked at it all but I will look at it again, never hurts and I may have missed something. But everything is new, dizzy, cap, rotor, points and condensor.
Re: Spark color?
Post by brute4c on Sept 18, 2006, 11:00am
However the coil is getting only 5.4 volts, it needs to be 12 or so when cranking and then, most systems usually drop it to, 9-9.6 volts in the run mode....
You need more voltage in start mode...whether your reducer is doing it or batteries are low or whatever, you need to increase that voltage to get a good spark...
Re: Spark color?
Post by tomcat on Sept 18, 2006, 11:28am
The voltage reducer maybe the problem. If its a switched circuit type it requires a minimum voltage to work. This voltage drops too much while cranking the starter so the reducer cannot work properly.
Other possibility is that the voltage reducer cannot deliver enough current. Depends on the coil.
If you know somebody whos firm in electronics he can calculate you a proper resistor which would be enough for running the 12v coil on 24 volts. Must be a power resistor. Had this in one truck long time ago and it worked fine.
But first try the one battery trick mentioned before.
Re: Spark color?
Post by barrman on Sept 18, 2006, 11:59am
What color is the spark at the points when you are cranking the engine? Use a screw driver to make the points spark with the engine sitting still. If you get the lame spark while cranking and bright blue while sitting, then I agree with the comments about your reducer being the problem.
Re: Spark color?
Post by porkchop on Sept 19, 2006, 6:17am
With the screwdriver I get a nice blue spark. I threw the battery charger on the one of the batteriers last night and will do the other today, just to be safe. I am then going to try it without the convertor and see what happens.
Re: Spark color?
Post by porkchop on Sept 19, 2006, 4:56pm
Got home from work and tried it again with two freshly charged batteries. I left the convertor on to see what I was getting while cranking and I was now getting 14.4 volts, this is with the convertor still hooked up. So I dumped a little gas in it and tried again. It sounded like it wanted to go but just wouldn't go. I played with the dizzy and I figured that it must be off. I moved the wires over one and then tried again. IT CAME TO LIFE!!! Boy is it loud with no exhaust and in the garage. It would not idle but I need to make some adjustments. Just happy that it started. One step closer to finishing. I am going to get it to move under it's own power and then pull it out of the garage to make all the adjusts. It won't be so loud and the exhaust fumes won't be bad. When it is all done I will take it to the exhaust shop.
Re: Spark color?
Post by hiker on Sept 19, 2006, 8:44pm
HURRA!!
Re: Spark color?
Post by oilcan on Sept 20, 2006, 5:58am
GOoooOO PORKY!
Re: Spark color?
Post by barrman on Sept 20, 2006, 7:42am
Way to go!
Re: Spark color?
Post by brute4c on Sept 20, 2006, 9:21am
YOu got a couple screaming groupies in Wisconsin cheering for ya Gunny!!
Re: Spark color?
Post by oilcan on Sept 21, 2006, 9:08am
Wish I had groupies.
I'd even settle for a few groupers.
Re: Spark color?
Post by porkchop on Sept 21, 2006, 9:17am
Cool! Groupies!
I am hoping the weekend of the 30th to have all the remainder of the stuff done, that is if I can figure out how to rig up the throttle. I will get a picture of the setup and see what other ideas are out there.