I have an FJ40 with a 350 Chevrolet engine.

The engine has HEI and 4 brl carb.

The engine was running quite well. The cruiser sat for about 4 days. When I went to start the engine - the engine would not start. The engine has a GM HEI ignition and 4 brl carb. I checked and I was not getting any park at the spark plug. I check and 12 vdc is being supplied to the distributor + side.

I have rplace the ignition module with a new Accel (P/N 35361) and replaced the coil with an Accel Super coil (P/N 14003) still no spark.

Any assistance you can offer to determine what is wrong will be greatly appreciated.

Thank You in Advance,

Steve

Hmmm...me thinks you should get out a voltmeter before you start the shotgun approach of replacing parts.

Let's start with the basics.
1. Ohm the plug wires. <5000 ohms per foot is acceptable

2. Pull the cap off and make sure there isn't any carbon tracking going on and that the rotor isn't grounding through the dizzy shaft.

3. If that all looks good it is time to look at the coil. Ohm from the primary side out through the tach signal. IIRC you should see 1-3 ohms on the primary side, but double check. If you have infinite resistance it is time to get a new coil. Now do the same for the secondary side of the coil...run from the input to the coil output and make sure you don't have an open circuit. I *think* GM calls for about 20,000 ohms on that side, but I really don't know for sure. Finally, check from the coil terminals to the core to make sure it isn't grounding there.

4. Assuming that all checks out I would start looking at the ignition module and PM generator. You should be seeing about 250mv AC coming out of the pickup coil. If not it would be time to replace it.

Yeah...that's all I've got for now cause I'm tired. If you go through all that and still have nothing we can go from there.

Thanks for the reply.

The engine was running great until it set for about 4 days.

The plug wires are relatively new. I do not think it is the plug wires becasue I do not seem to be getting any spark output.

The cap and rotor are relatively new ( but did check and no tracking).

The coil is new.

The ignition module is new.

I am not that familiar with GM HEI systems. You mentioned "you should be seeing about 250mv AC coming out of the pickup coil".

How do I check this?

Is it simply putting a volt meter across the wires coming off of the magnetic pickup and measuring the voltage with the engine cranking?

Thanks for your help.

Steve

Is it simply putting a volt meter across the wires coming off of the magnetic pickup and measuring the voltage with the engine cranking?

Thanks for your help.

Steve

Yep.

*edit* You can also check the resistance of the coil, but I can't remember what it should be off the top of my head. I'd check voltage first and go from there. If you discover that the pickup coil is bad it's often just cheaper and easier to throw a rebuilt dizzy in.

I greatly appreciate your help.

I can check the magnetic pick-up output tomorrow.

Considering the other checks that I have already completed - I am thinking it is the magnetic pick-up but I did not know how to check if it was working properly.

Just to be clear, I check the magnetic pick-up output with the cap off. The voltage output is generated by the magnetic pick-up and it does not need to be energized.

Is this correct?

The voltage output will be AC so I need to set the volt meter to mV AC.

Is this correct?

It sounds like this is something that I could check on the bench (providing I have a way to rotate the distributor shaft) - it would be easier on the bench.

Thanks Again,

use a drill to rotate it.

Feel free to bench test things using a drill as posted above. I just like to avoid knocking things out of time if I can. Putting it back at time is not hard at all, but it is one more thing to do.

Otherwise you are correct. It will be a small AC voltage that you will be checking with the meter. PM generators are self energizing as opposed to Hall Effect sensors which would require vRef and an energizing voltage. This is what makes PM generators well suited to speed sensors among other things.

The saga continues.

I checked the output from the magnetic pick-up and the output was as you described. As I increased the shaft speed, the output increased.

So the magnetic pick-up seems to be working properly.

The module is new.

The coil is new.

I am wondering if there was a grounding disconnect for some reason that this might account for the lack of spark.

I am considering setting up the ignition system on the bench and verify that I can get spark from the system off of the engine. By using the drill to rotate the shaft and providing 12 volts to the terminal - I should be getting spark out of the wires (I would verify using a spare spark plug).

If my understanding is correct, the distributor housing should be grounded through its mounting/clamping system.

So:

1. I would ground the distributor housing and the spark plug.
2. Apply 12 VDC
3. Rotate the distributor shaft

I should see a spark - correct?

Thanks Again for your help.

Steve

much simpler to test n engine-simply pull coilcover & ck w/test light on red & yellow wires.red key hot,steady power while cranking & yellow(some coils also come white)wire should be blinking on & off or flashing.this is neg side of coil
if flashing electronics(module/pickup)ok.if flashing but no spark @plugs look for bad rotor button/coil arcing to grnd frame

ps make sure ground strap to center slot was put back in & is a good ground w/cap plugged in to dist harness

mmk5blazr,

I setup the HEI on the bench like I said I wanted to do and I get a spark.

This confirms that the distributor is OK and that the coil, rotor, module, etc. are working OK.

When I reinstall the distributor in the engine - no spark.

What is the minimum voltage required to energize the GM HEI system?

I plan to check for bad ground tomorrow.

Any other suggestions?

Appreciate your help.

I don't think the issue is that you aren't getting or making enough voltage...I think your problem is that you are grounding out somewhere, most likely through the dizzy shaft. As long as you still have it out of the truck and on the bench, repeat the test again, but this time run a little jumper wire from the dizzy shaft to the 12 volt battery you are energizing the ignition with. I bet you won't get spark in which case your rotor becomes really suspect, relatively new or not.

You are getting 12vdc from the ignition switch in the truck, right? You checked that by jumping it from the battery with the dizzy in the truck I'm sure. :D

I measured the voltage to the distributor (key on) and measured 11.5 vdc.

During cranking the voltage drops to about 7 vdc.

I recall some ignition systems have a minimum voltage required to have the system function. I was interested in knowing if the GM HEI has a minimum required voltage.

If the voltage is too low, I could put a jumper from the battery (i.e., bypassing the ignition switch system).

Thanks for the suggestion.

I'm not sure what you mean by the "dizzy shaft".

I am using a 12 vdc power supply (not a battery)

If I jump from the distributor gear to ground, is this the check that you are suggesting?

Thanks Again,

dizzy shaft=distributer shaft. I'm lazy and don't like typing it all out. :D Yes, you are correct. Run a jumper from the distributer shaft (not the gear...that's going to be spinning) to the power supply negative and make sure you're still getting spark.

During cranking is when you should be seeing the most voltage. Even the older trucks that used a ballast resistor bypassed it in cranking mode so they got a full 12 volts when cranking before dropping to ~7-8 volts when running. Your drop to 7 volt concerns me.

So...

1. Get the battery tested or throw in a KNOWN good battery to test that. It sounds pretty damn suspect. What is your open circuit voltage?

2. While cranking do an insulated voltage drop test by running a voltmeter lead from battery positive and the other to the 12 volt feed to the ignition. You shouldn't see more than maybe .3 volts. If you are I would suspect your ignition switch or something on the cranking side of the circuit is an issue.

I measured the voltage to the distributor (key on) and measured 11.5 vdc.

During cranking the voltage drops to about 7 vdc.

I recall some ignition systems have a minimum voltage required to have the system function. I was interested in knowing if the GM HEI has a minimum required voltage.

If the voltage is too low, I could put a jumper from the battery (i.e., bypassing the ignition switch system).

Thanks for the suggestion.
Low cranking voltage is bad. If the dizzy is still in the motor run a jumper from the battery to the dizzy and try to start it.

Low cranking voltage is bad. If the dizzy is still in the motor run a jumper from the battery to the dizzy and try to start it.

HEI requires at least 8 volts to even register.

those pickup coils suck, every time the engine runs, the vacumn advance moves the pickup coil and pulls the wire a little all the time, go to the side of the pickup coil where the vacumn advance is screwed onto and pull on those wires, I bet one is broken. I had a car that would run at an idle, then as soon as you revved it up, it was like someone shut the key off. The pickup coil was moving with the vacumn and losing connection. I replace a few of those a month here at the shop....just check it, it will be fun....I promise.

any success?jumper wire give you spark?