No spark, no fire, no sense

[acl]

A week ago I parked my truck in the garage after a nice country drive. Got in it next time would not start. NO fire. tested module Ok. Changed it anyway because it had a crack in it. (FYI tested at auto part store, Took 3 new modules off shelf to get one that tested ok). NO fire. Changed coil and started, ran for a few and died. NO fire. Have 12v plus at hot wire to coil when key is in ACC. When cranking it drops to 10-10.5 Tried to start again yesterday, and it fired once and the once again NO fire. Any thoughts. Sorry its a 68, 350 hei.

[cdowns]

there should b no voltage to coil when key is on the acc position// votage only at run and start positions

[68gmsee]

May be starter drawing too much current, weak battery, battery cables, loose or dirty cable connections at starter, distributor or to ground.

As a first test while cranking place a meter across the + and - posts of the battery. It shouldn't drop below approximately 10 vdc.

Sorry, I see that voltage stays at 10 to 10.5. Disregard above. The cable connections inside the distributor should be checked as well as possibility of arcing internally in the cap and rotor. You should see hairline cracks and/or sometimes a pinhole in the rotor if it's arcing.

[indianbullet]

+1 on the hole in the rotor, GM HEI are notorious for burning a hole through the rotor if its a cheap rotor.

[acl]

Originally Posted by cdowns

there should b no voltage to coil when key is on the acc position// votage only at run and start positions

Sorry, the on position, right before cranking.

[MacGyver72]

Since you get periodic firing, I suspect you have a short or a loose connection on the distributor wire. First unplug this and check for current with a simple test light. Pull and twist on it a bit to see if you see a loss of connection. If that is good clean the contacts on both the coil connection under the cap and the female connection on the wire you just tested. Make sure that it isn't loose once you plug it in.

[acl]

Wil change cap and rotor tonight, any idea about a "pick up coil" ?was told it it on the dist. Shaft?? Can they go bad? Thanks Gary
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[umwtnt]

I once had a starting problem similiar to this and I found out the hard way I did not have a proper ground between the engine and the frame where I originally had the battery ground connected to. I burned up 3 modules before I learned this. Good luck.

[MacGyver72]

I don't know if the "pick up coil" you're referring to is the connection between the rotor and the coil but it could be. I forgot to install that little piece years ago when I replaced a coil and the engine ran fine for about twenty miles when the spark jumping from the coil to the rotor (about a 3/8"gap) caused the underside of the cap and the top of the rotor to melt away. It's a little button that sits in the top of the cap against the bottom of the coil. It's spring loaded and is the connection from the coil to the center of the rotor under the cap.

[eseaton]

pick up coil is in the distributor but you have to remove the dizzy and disassemble to replace and yes they can go bad.

[MacGyver72]

Cool! I love learnin' Didn't know what that little thing on the shaft was called. I've never had one go bad. Distributors are cheap at the junk yard. If I had to completely disassemble one, I'd think seriously about just buyin' another and replacing it. Just my opinion.

[acl]

I agree with getting a new dist. Just would like to know if thats the problem first. Wifes list got in the way of new cap and rotor last night, hopefully tonight. Thanks for all the idea, and keep'em coming if there is something else, gary

[MacGyver72]

Don't forget that little button under the coil and on top of the cap. Hopefully just a cap and rotor will fix it but your symptoms don't sound like a cap or rotor issue to me. The coil pickup on the distributor sounds logical with your issues but then again so does a shortage in the wiring.