So my g/f's 86 firebird w/ a 2.8 wont start. With key on, battery voltage is 11.8, 12.1 with it off. Motor cranks fine with this voltage. With key on, i checked voltage across the coil connector and i got 10.6 volts. is this enough to create spark? I cant figure out whats wrong any help would be greatly appreciated

 

do you mean it cranks, but no start? ifso the coil is probably bad if no spark. check connections first . if no spark get a coil,hth jimmy

 

it cranks with no start. i checked the coil using the 3 tests with an ohmmeter recommended by gm and it checks out alright. a friend got me the gm diagnostic procedure from gm and it got me down to "change the coil, if that doesnt work change the module" which is kind of expensive since i dont really think the coil is bad and theyre most likely unreturnable

 

Did you pull a spark plug wire off and test for spark first? Rotor button or dist. cap bad?

There should be two wires on the coil. Pnk/Blk should be key on power 12v and Wht should be the ground that switches the coil.

Hook one end of the test light to 12v source and with the other end back probe the white wire while cranking. Does light flash? Yes. Replace coil. No. Replace ignition module.

 

hm, i wish the information i had from all data broke it down like that. and yes i checked for spark first, i replaced the rotor and cap cuz they were kind of old and i figured it would be a good start. So my coil has 4 wires the one red and black, black and white on one connector, and two blacks on a second connector. i did this test on the black and white wire and the light kind of flickered so i'm going to try the coil. thanks for your help, much appreciated

 

While the engine is cranking you will get on and off voltage checked across the + and - coil terminals. That's the coil alternately charging and firing under the control of the module. It works by supplying constant 12V+ at the coil's + terminal and then having the module alternately supply and deny a ground connection at the - termal of the coil. When it supplies the ground connection the circuit is complete and the coil charges up. When the ground is removed the circuit is broken, the magnetic field in the coil collapses and the coil fires. Sounds like you've got voltage and your module is doing it's job.

 

So it ended up being the coil just wanted to post in case anybody searches for future reference