help coil wont fire!!!

[wildchild]

70 chevy short step 250 6cyl has electronic ignition coil has 12 vols in but nothing out replaced coil no change anyone have any ideas that might help?

[chevy72blu]

Originally Posted by wildchild

70 chevy short step 250 6cyl has electronic ignition coil has 12 vols in but nothing out replaced coil no change anyone have any ideas that might help?

I assume you checked the ground?

[wildchild]

yes i have thanks

[89 crew]

There are not many options with coils. if you have power going in, the ground is good, and nothing coming out, the coil is bad. Did you test for power at the wire, or at the coil terminal? You said this is electronic, are you talking HEI, or upgraded points system, or after market? If it is hei style did you check the button under the coil?

[wildchild]

electronic all four teminals show 12 volts tried 2 different coils with the same result has 12 volts to module in distributor also but nothing to coil wire

[72lb4x4]

I'm no expert on electronic ignitions, but with the key on, chances are no voltage will be on the coil. With the starter cranking, you should get pulses of 12V to the coil, buta meter is unlikely to actually read 12V.

Is it an HEI, with the coil in the cap? Sorry, "electronic" isn't clear.

It could be the pickup, or module for the ignition if it isn't the coil.

[caminokid]

If the module is good then its the pick up. These are common on high mileage engines.

[wildchild]

it is a hei out of a 77 straight six the coil is not in the cap it has the same coil as a 94 chevy with a six in iti just replaced the module and pickup coil but havent put the distributor back in yet but i went to a local mechanic and tested the pickup coil showed good but he sugested replacing it because he has had bad ones that tested good he said if that doesnt work hes stumped

[wildchild]

it is a hei out of a 77 straight six the coil is not in the cap it has the same coil as a 94 chevy with a six in iti just replaced the module and pickup coil but havent put the distributor back in yet but i went to a local mechanic and tested the pickup coil showed good but he sugested replacing it because he has had bad ones that tested good he said if that doesnt work hes stumped

[stope4]

I think it's 12 volts to coil from ignition, then 12 volts to module in distributor. Hook everything up like normal. Turn key to on. Test voltage into coil and test voltage out of coil. Do this by placing red wire from tester on the positive side of coil and then on the negative side of coil. Put black on a ground like the inner fender, brake booster or firewall. Should read somewhere between 11 - 13 volts on the positive and negative side of coil. If you get these readings in and out of coil, coil appears to be good and ignition switch appears to be good. To check ignition switch, turn key to off and check voltage at coil, should be zero. Next step would be to remove the HEI module from distributor and go have it tested at local auto parts store. More than likely this is bad if above test shows coil and ignition good.

[89 crew]

Do you have any pictures of your distributer? Something sounds wrong here. In the 77 inline 6 the coil is in the cap. If you get older then it is out of cap. In the 94 v6 there are 2 wire looms that plug into the coil. Unless you have done a lot of upgrades to your truck it won't have those plugs. I'm wondering if it is an after market msd or similar and is suppose to use a straight coil instead of computer controlled.

[wildchild]

my camera is broken but the coil is a c835 you can see it on autozone .com the distributor is a 30-1691 and the cap is a dr902 all say they are for a 1977 1/2 ton chevy with a 4.1 250 six cyl i drove a 15o miles yesterday to get a new pickup coil that didnt work either a local mechanic that has been in buisness for thirty years says he doesnt understand it either it should fire i dont understand it ive tried 3 coils 3 modules and three pickup coils coil and the distributor have good grounds and both have power when cranking but no spark to coil wire im about ready to buy a new points distributor at least i know i can get it to fire
alsom this is not a new distributor swap it has been in the truck for years

[89 crew]

I looked up your coil, it looks like there are 4 wires going into it. Where do they go? 2 to the module? and 1 or 2 hot? or is the second wire a ground?
I also looked at a pic of the distributor, it looks like a standard hei on the body. Will the cap from a hei fit it? If so throw away the off cap coil, cap, rotor, change the wires coming out of the module, hook up a hot lead and you should have it running at least.

[wildchild]

the four prongs 1 is for the hot 1 is for the tach and the other 2 are for the module

[wildchild]

thanks for the help everyone i finally got it running pulled the distributor out tore it a part cleaned it up again put it back together and it worked i dont know what i did but it worked finally cant wait to drive it again its been four long years thanks everyone for all your help