MattL

Hot Spark no spark - any suggestions?

12 posts in this topic Last Reply

Recommended Posts

I recently installed a Hot Spark electronic ignition unit in the Bosch distributor on my new '76. I also installed a new Behru blue coil at the same time. (I bought the coil from Hot Spark to ensure I wouldn't have a coil-related issue.) I took the distributor out of the car to install the ignition unit. In the process, I cleaned things up a bit and removed the condenser. Wrapped it all back up, re-installed the distributor at TDC, and cranked. The engine turned over, but didn't start. I realized (thanks to a search of the FAQ!) that there was probably a resistor wire in place. There was, so I replaced it with regular 14 gauge wire, and tried to start again. No luck. Tried rotating the distributor up to 90 degrees in each direction. No start and no apparent change at all. It doesn't seem like there's any spark at all, and I can't get my new timing light to flash even a little. 

 

I've since double-checked that the rotor is correctly oriented to #1 at TDC. I've also checked the igniter resistance, coil resistance (primary and secondary are both good) and the voltage at the coil (good @ ~12V). 

 

Any suggestions would be much appreciated. Please make no assumptions regarding my intelligence or skill level: I won't be offended by any suggestion, and it's very possible I made a basic mistake that caused the problem. I have searched the FAQ every step of the way, but I think I've run out of things to try. Today was such a beautiful driving day, that it was heartbreaking to spend it grounded in the garage! Thanks in advance!

Edited by MattL

Share this post


Link to post
Share on other sites

Have you checked that the rotor is actually turning when you crank? You may need to push the shaft in further to engage with the cam. As you insert it the rotor will roll around due to the slew gear. Wherever this ends up, rotate the body of the distributor so that the rotor is pointing directly at one of the posts in the cap. This is then your number 1 cylinder, tighten it down and the run the rest of the wires in clockwise(? I always get this wrong as 50/50 call) order 1,3,4,2. 

Share this post


Link to post
Share on other sites

Thanks for the reply, Simeon! Unfortunately, yes, the shaft is all the way down. The rotor spun about 30 degrees clockwise as it seated. So, I assume it's spinning. 

 

One thing I forgot to mention initially: while I still had the engine at TDC and the rotor pointed to #1, I set up the timing light and turned the ignition on (without starting). I would have thought the light would turn on, but no such luck. 

 

 

Share this post


Link to post
Share on other sites

If you put a test light (not the timing light) between the coil negative and ground (on the engine). When you crank the engine, the test light should flash if the hot spark is working. When the internal ‘switch’ (it’s probably a transistor) opens the test light should come on, when the switch closes it will short out the test light and turn off. 

 

Have you checked for 12V at the coil positive terminal? Is the Hotspark red wire connected to this same 12V? The Hotspark black wire goes to the negative terminal. You should also leave the car’s black wire connected to the coil as well and the connection that would have gone to the condenser connection on the distributor should be left disconnected, insulated and tucked out of the way. 

 

 

Share this post


Link to post
Share on other sites

I'll get a test light and give that a shot; thanks. In response to your questions:

- Yes, I checked the voltage at the coil +, and it's 12V.

- Yes, the Hotspark red wire is connected at that same terminal, and the Hotspark black wire is connected at the negative terminal.

- The car's black wire - okay, THIS could be my problem! When I get home from work I'll have to check that this is connected. There are a couple unidentified wires I had left unconnected, adhering to the Hot-Spark instructions to "only connect these few wires." This could be one of those left unconnected, and it would explain the whole thing. Obviously, if there's no ground, there's no current! 

- Yes, the condenser is removed completely, and there are no related connections hanging about.

 

Thanks again, Simeon! I'll let you know how I make out with the black wire suggestion.

Share this post


Link to post
Share on other sites

You should have about 13.5 volts at the coil when running.  I got 12.5 volts with the resistor wire in there.   Take it out, trust me, i think it messes with the current (somehow). 

Share this post


Link to post
Share on other sites

Hi, Dude! I've already taken the resistor wire out and replaced it with regular 14 AWG. One of the first things I did when it didn't start right after the upgrade.

 

Before I took the points out of the distributor, they were connected to a double black (I think) wire just long enough to reach the distro from the top of the firewall. Now they're not connected to anything. Should they be? 

 

In addition to those, there are three other wires not attached at the moment:

 

1. Sharing a blue rubber housing:

- 1 Red/black - starting sequence ignition wire?

- 1 Solid Black - Original black from distributor/points?

 

2. Single wire in its own blue rubber housing:

- 1 Solid Black - Tachometer?

 

I've tried connecting all three of these, individually and in combination. Still won't start, and still no flash from the timing light at all (the inductive wire is clamped to #1: shouldn't this act as a test light, Simeon?). 

 

Out of ideas again. Thanks for the continued suggestions. Keep 'em coming if you've got more! 

Share this post


Link to post
Share on other sites

By test light, I literally just mean a 12V bulb. This is usually packaged in a probe with a wire and crocodile clip. The inductive pick up only works on the HT leads. As the name suggests a pulse is induced into the pick up when the spark plug fires, this is then used to trigger the timing light flash. No spark, no flash. 

 

Your problem is most likely with the low voltage wiring so aside from confirming that there is no spark, a timing light is no use for fault finding. 

 

Make sure that you don’t have any extraneous connections to ground as well. The black connection with two wires that was previously connected to the terminal on the distributor needs to be insulated with some tape and secured clear of touching ground on the body or engine. 

 

The minimum you you need to get the engine to run is battery voltage to the coil + plus the red wire on the Hotspark and a wire between the coil - and the black wire on the Hotspark which then grounds through the body of the distributor. Screws inside the distributor nice and tight? Magnet collar seated down well on to of the shaft? If you put the test light (12V bulb) across the coil negative terminal to ground, this will tell you if the Hotspark is switching or not. 

Share this post


Link to post
Share on other sites

I'll get those orphaned wires taped up and secured, check the screws and magnet collar in the dizzy, and get a test light wired up. I'll report back with the results. Thanks, Simeon. I appreciate the help. 

Share this post


Link to post
Share on other sites

I've taped up and secured the double-black wire formerly connected to the condenser, and I've double-checked that everything's tight in the distributor. The coil has the following connected to it (other than the high-tension lead):

Negative:

- Hot-Spark black wire

- Test light probe, with clamp connected to engine. 

 

Positive:

- Ignition wire (not resistor wire)

- Hot-Spark red wire

 

When I hook up the test light, it turns on as soon as I turn the key to On and stays on until turned to Off. There's no flashing: just a constant light.  

 

I know I must be doing something wrong. Any corrections to my setup above?

Share this post


Link to post
Share on other sites

If it isn’t flashing then it looks like your hotspark is DOA (or the magnetic pickup isn’t working for some reason). The test light staying on permanently says the ‘switch’ isn’t closing. Try another, or go back to points and a condenser. 

Share this post


Link to post
Share on other sites

Well, at least I know what to do now. Thanks a million for your help, Simeon! I have to squeeze all my wrenching into about 2 free hours per week, so your guidance is much appreciated. 

  • Like 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now