350 Chev wont start

I have started to have an intimintent problem with my 350 chev when starting.

Sometimes it starts fine and then it wont. It has to be electrical as there is plenty of fuel getting through.

I just went to start it now and it wont start. There is no spark from the plug leads and no spark from the lead direct from the coil. There is power to both sides of the coli with the ignition on.
I put on a coil that I had lying around thinking this was the problem, it fired then died and wont restart.

Any ideas???

Is it the coil? Im not convinced that it is yet.



Aaron

 

need more info about your vehicle. year, carb or injection, ignition type, etc...
you said you had power to the coil with the ignition on, but have you checked it with the ignition switch in the start position ?

 

It is actually a conversion into a SWB FJ40 Landcruiser.

Its carby (600 Holley)

Electronic distrbutor ignition.

Turbo 400 auto

I havent tried to see if there is power to the coil when cranking. Only with the igniton on. Will try that next.

Should there be power to both sides of the coil when cranking?

 

Possible ignition module issue; they do go bad sometimes. Should be power to the coil whenever the ignition switch is on.

Depending on what the motor came out of, the module may be external to the distributor or mounted inside.

 

Yes. And the negative terminal voltage will pulsate (flutter on a voltmeter) between 12 volts and to a lower volts when the distributor cam rotates. The change in the volts is due to the charging up the secondary windings so it can fire off a spark of 20,000 volts or more.

 

My question is... Is the coil the HEI type that is mounted on top of the distributor cap? If so, there is a ground strap inside the cap under the coil. This ground strap is also one of the pins of the connector for the coil.
Hope this helps ya,
Billy

 

OK,
Finally got around to having another look at it.

There is definatly no spark comming from the coil.

There is constant power to the positve and negitive sides of the coil when the ignition is on.

This voltage drops to about 10 volts when cranking, but does not pulsate at all.

How do I test the ignition module??
What does it look like?? I dont think it is external to the dizzy.



Cheers
Aaron

 

If it's inside it may look like these:

http://www.nextag.com/gm-ignition-module/search-html

Check the two at the top, they are similar to what's in my 350.

Some auto parts stores can test them.

 

Better pic here:

http://cgi.ebay.com/ebaymotors/IGNIT...8490QQtcZphoto

 

If the negative side does not go up and down in voltage, I'd be most suspicious of that part that causes the break in the current, which is what does the picking up in the distributor, whatever type you have. As that is the mechanism that diverts the current away from the negative side of the coil, to ground, as the distributor rotates. Have you even taken off the distirbutor cap cover while cranking to watch to see it rotate? Can you describe the looks of that distributor to us?, as per Billys68ss post?