ignition

[slayton67]

went from points to electronic ignition and now it only starts when you let off the key?

[Kurt Combs]

Does the new electronic system require a full 12 volts? If so did you bypass the resistor wire from the ignition switch?

[basketcase0302]

Kurt Combs on Wed Mar 28, 2012 9:59 pm
Does the new electronic system require a full 12 volts? If so did you bypass the resistor wire from the ignition switch?

I believe that most electronic ignitions require more voltage than the resistor wiring will allow to feed it. It should be the pink colored wire coming from the ignition switch / it goes into the harness for a short period / then heads to the engine compartment through the firewall.

[70-360fe]

went from points to electronic ignition and now it only starts when you let off the key?

I would check the voltage at the coil with the ignition turned on and see how much and when you get voltage. Depending on the coil, if you changed will decide how much voltage you will need at coil. If you did not switch out you should get around 8.5 volts at the coil with ignition on. What system did you switch to?

[slayton67]

i got the motor and brain box out of an 84 f150 and one wire goes to the starter wire on the silinoid and the other goes to the aux plug ins in the fuse box i tried putin one wire on the ignition wire on the silinoid but it still started the same when you let off the key

[colnago]

slayton67,

This is what I think is happening (others, please correct me if I get anything wrong):

When you turn the ignition, the 12V goes through the ballast resistor to your coil. This lowers the voltage being supplied to your coil during startup. When you let go of the key to run the engine, the 12V goes through a different wire, and the coil gets the entire 12V. An engine with points uses this type of system; lower voltage during start, and 12V while running.

However, some electronic ignitions (like my Pertronix) needs the full 12V even during start-up. That's what Kurt Combs and Basketcase are talking about when they suggested bypassing the ballast resistor. It doesn't matter if you have a newer motor; the electronic ignition still needs the ballast resistor to be bypassed.

When you're cranking the engine, the electronic ignition is not getting the 12V. But as soon as you stop cranking, it does get the 12V (from the other wire path), the engine is still turning (momentum from the starter), and now the electronic ignition is able to work properly.

Another problem I had with my Pertronix was that when I put in the magnet ring, I pushed it all the way to the bottom of the distributor shaft. This put the magnets too far away from the pickup, so the engine wouldn't start. Once I brought the magnet ring to the same level as the pickup, it started right up. This probably isn't your problem, since it sounds like it starts and runs when the key is in the "run" position), but you might check it. What system are you using?

Here's a link to the '67 ignition wiring (my truck's a '67, so this is the diagram I'm familiar with):

http://www.fordification.com/tech/wirin ... gauges.jpg

Down in the lower right corner, you have your ignition switch. Wire 16 (red/green) comes out, then goes to 16A (pink). This pink wire is the ballast resistor, and needs to be bypassed.

Hope this helps,

Joseph

[slayton67]

i have no clue wat any of that ballast resistor is would it start right if i just put points in it? and that diagram is like a maze for me i aint to good with electrical stuff

[SmoothJ69]

The ballast resistor in the original wiring is a thick pink wire that goes from the ignition switch to the coil, and reduces the voltage being delivered. From your description about getting a 'brainbox' and whatever else from an 80's model truck I assume you mean the duraspark system.

If your truck will only start when the key is in the run position, then you are likely not getting power to the coil during start. Like how your radio shuts off while you're crankin the motor? your coil is doing the same thing probably. Assuming I am right about duraspark then this might be helpful, shows the pink wire disconnected at the ignition switch. http://www.mustangsteve.com/conversion.html

[Kurt Combs]

Is the new electronic distributor and system a Ford Duraspark? Or did your donor truck have a computer that controlled the ignition? I am not familiar with 84 Ford systems, but Duraspark I have a basic understanding of and could probably head you in the right direction.

[slayton67]

how would i tell if its a duraspark system or whatever?

[Kurt Combs]

It would have been removed from a Ford truck made in 1977 to 1979. It would have an aluminum box on the driver's side fender well and the distributor would not have points. It would be wired a little different than your original ignition wiring.

[SmoothJ69]

I thought the duraspark II went thru the mid 80's but I may very well be wrong. the distributor has the 'wide' looking cap.

[slayton67]

the box sounds right and the distributor is really big like he said but it has the 67 ignition and everything and the motor and box and stuff came out of an 84

[Kurt Combs]

I have no experience with trucks from the 80's, so I wasn't including them in my comment. If you have a Duraspark system, you need to look at some of the wiring schematics online so see if you hooked it up right. They do require a lead of 12 volts to the red wire while the ignition is on. This lead shouldn't be from the pink resistance wire that goes to the coil. The red wire I am referring to goes into the aluminum box you should have mounted on the fender well, or at least away from the engine's heat. How about posting some pictures of what you have installed on your bump, that would help.

[slayton67]

i just put points in and fixed the problem thanks for the help