I've got a 1986 full size K5 Blazer with the 305 ci engine. I have no spark and can't seem to figure out why. This has the coil-in-cap HEI ignition. The ignition module tested good (I had a new one and stuck it in anyway) the pick up coil tested good the cap and rotor are new. 12 volts to the cap. Ignition coil tests good as well. Don't know what to make of this one. The vehicle doesn't get driven much any more, just sits in the garage. I start it up every couple of weeks and let it warm up. I went out to fire it up a week ago and no spark.

 

Do you have +12V to the coil power wire?

 

I do have 12 volts to the coil power wire.

 

Here's an update on my dilemma. I ran a hot wire from the battery to the bat side of the distributor cap. Started right up and purred like a kitten. Tinkered around a bit more and decided to fire it up and move it forward so I could close the garage door. Wouldn't fire back up. Decided to heck with it it's to cold out to mess with and buckled everything back as it was and for whatever reason it fired right up. I have no idea what's causing this. Sounds like a bad wire someplace, just need to find it now.

 

The wire that runs to the batt terminal on the HEI distributor should be to an ignition switched source which is hot in run & start only.

 

Quote:

Originally Posted by swartlkk

The wire that runs to the batt terminal on the HEI distributor should be to an ignition switched source which is hot in run & start only.

There are actually two wires going to the batt terminal on my distributor. One runs to the ignition fuse on the firewall and I'm not sure where the other runs to. It runs back behind the engine to the passenger side and into a harness. One wire has 12 volts with the key on the other has nothing.

 

The second wire on the distributor is ground and used to send a signal to a tach if you have one. The other is 12V only when start or run as swartlkk said. If your having intermittent problem with the dist im guessing that something inside is bad or going bad and that is your trouble. Probably the ignition module or pickup coil inside the distributor. But you can check the coil with a OHM meter to be sure. Also inspect the rotor as they have burned thru in the middle where the coil spark goes.