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1972 chevy nova no spark


Guest 72_inline6_nova

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Guest 72_inline6_nova

hello everyone im fairly new to this site and am not sure if this is the correct area for this type of post but i have an issue...

i have a 1972 chevrolet nova. its a 4 door.. 250 inline 6. the issue im having is i was driving it. ran fine all day. pulled into gas station filled up with gas and when i went to re-start it and nothing.... it just cranked. after pushing it to a parking spot i checked for spark first as i new i had fuel i could see it being pumped into carb, checked spark nothin. i have 12 volts to the + on coil and 12volts on the - of the coil. and bo spark from the coil to distributor. what i than did was replaced the coil, and nothin so thinkin maybe o'riley gave me a bad coil i got another one and still nothin, i popped the distributor cap and put screwdriver between points and no sparking happened so i bought a new set of points and still nothing i have checked for a fuse or fusable link for the ignition system and i only found one bus style fuse replaced it and still nothing im at a loss does anone have any ideas? i even ran a hot wire directly from battary to coil just incase and still nothing. anyone have any ideas suggestions anything? this is my daily driver and is startin to really irritate me. i appreciate any help i get thank u in advance :)

Edited by 72_inline6_nova
typo (see edit history)
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Guest 72_inline6_nova

good idea. but wldnt i still get a lil spark if coil wire was bad? i mean ill try it for sure. other than that what cld it be

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Head on over to www.NastyZ28.com and look for wiring diagrams for your model year of vehicle. Camaros and Novas should "wire" the same. You should find copies of the GM Factory wiring diagrams on that website.

As you know the "start" function of the vehicle works, possibly the issue is in the "run" function of the ignition switch? What you put the ignition key into is ONLY the lock cylinder, which via a gear setup, runs a "rack" rod down the steering column to the ignition switch mounted near its firewall end. Not hard to change once you find out where it is. I'd recommend running the seat all the way rearward and then (if you can get into that position), end up with your head in the floor underneath the column. Much easier than trying to lay sideways over the door sill! You can hand your legs over the top of the seat for stability. Just dont' stay that way too long! Once you see where everything is and how it's laid out, then quicker "on your side" things can happen.

Check out those wiring diagrams! The "fuse link" is only in the starter circuit. Might even be a ballast resistor for the points that's failed.

Just some thoughts,

NTX5467

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Guest 72_inline6_nova

thank you ill look into that ballast resistor and the ignition switch. do you know why they would just go out? is theresoething that wld cause them to go out or maybe it was just time for a new one? again thank you ill get those diagrams and do some more testing

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Does the engine crank at all? If the fusable link going to starter is burned I would think it wouldn't. Check the condition of the cap and rotor. Bad plug wires? They should not exceed 7 ohms per foot.. Make sure when replacing the link that it's the same guage link as the original.

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Guest 72_inline6_nova

yes car cranks good and strong. nope tested all 7 wires resistances test good. cap and rotor are brand new. someone on another forum suggested tracing the yellow wire on the + side of coil back. they said if that has an open it wont have spark..

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i popped the distributor cap and put screwdriver between points and no sparking happened so i bought a new set of points and still nothing
When you do this test, the screw driver shaft can not touch anything else that is metal, other than the points "arm", or the test is no good; if the screw driver touches anything else, then you're grounding the circuit through the screw driver which is the same as the points being closed. You need to either push on the points arm such that the screw driver tourches nothing but the arm, or use a plastic device to open the points for your test.

If you have power to the coil and on to the points and no spark, you have either bad points, bad condenser, bad coil, or the points aren't grounded/grounding the circuit. None of the other stuff matters at that basic level; ign. switch, ballast, "yellow wires", etc. If you have power to the points, keep it at that basic level until you get spark by manually opening and closing the points. Are the points closing? Test for good ground, through the points, when they should be closed.

Edited by Tom400CFI (see edit history)
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Not if he did this right:

i put screwdriver between points and no sparking happened so i bought a new set of points and still nothing

If he did that right (w/o grounding the screw driver shaft) and still has no spark...doesn't matter if the dist. is turning. If he didn't do the manual point opening test correctly, then we still don't know.

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Guest 72_inline6_nova

i did check to see if the distributor was turning. distributor does turn normal. i did do the screwdriver test correcty i re did the test just bit ago to make sure as u said, yes the coild has 12v with KOEO and it drops to about 10.5v while cranking. car has NEW points NEW coil NEW cap NEW rotor NEW wiress NEW plugs so it cant be.any of those parts being bad. the points appear to be grounded but idk the only part i havent checked or replaced is the ballast resistor. everything else is new. i get the keeping it basic thing like u stated but ive checked and double checked and replaced the basic stuff like i said at this point i have power to the coil and power on - side of coil and no spark. thank you for everyones help so far i will check and make sure points are grounded and than i guess the ballast resistior otherweise i am still at a loss

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Guest carlnut50

I skimmed the replies so i might have missed something. If so, I am sorry. With a voltmeter, make sure you have power at the coil + term. then, at the coil - terminal. If you have power at the coil neg. go to the other end of the wire right on the points. With the points open there should be voltage. If not, the wire may be broken. They use a special flexible wire because it has to bend every time the vac advance works. If you have voltage there, close the points and the voltage should go to zero. The points are simply a switch and the coil is simply a stepup transformer. With that check you will have ign. unless your new coil, points, or condenser is bad.

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hmmm okay how do i test the points were do i physically test?
I'm trying to remember a test for this, put the test light leads on the + and - sides of the coil, crank the engine. The light should blink on and off, the points opening and closing?
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Guest 72_inline6_nova

no the points plate has a stud and the wire coming from the - coil and connects to the post on the points and than a second wire goes from the post to the condensor and they look in really good condition and your sayin clip the aligator clip on the test light to the + and the pointed tip to the - and the light should blink while cranking? is that right?

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no the points plate has a stud and the wire coming from the - coil and connects to the post on the points and than a second wire goes from the post to the condensor and they look in really good condition and your sayin clip the aligator clip on the test light to the + and the pointed tip to the - and the light should blink while cranking? is that right?
Each and every wire should be checked for continuity, including the one coming from the ignition switch. I'm thinking the alligator clip(ground) on the - and the point on the +, OR the clip on the distributor housing and the point on the points wire connection? As long as the test light is grounded.
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Guest 72_inline6_nova

justtried it. it didnt light upand ow i only have 4.62v on the + of coil and millivolts on the -... does that mean i fried coil? also since i only had 4v i jumped a wire rom battary straight to + of coil to assure 12v was there and nothing.

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justtried it. it didnt light upand ow i only have 4.62v on the + of coil and millivolts on the -... does that mean i fried coil? also since i only had 4v i jumped a wire rom battary straight to + of coil to assure 12v was there and nothing.
Will need to ohm test the coil, I have the specs, but not here. Do you have shop manual?
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Guest carlnut50

72 inline 6 . Go back and read carlnut50 post and check it out that way. It is not that complicated.

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With all due respect, every time I've tried to "ohm" an ignition coil OR suspected one was weak and replaced it . . . no change. Even when I ordered an AC-Delco one, it came with NO stampings on it, just an inked number on the bottom. Also, NO "Delco" logo anywhere to be found. This leads me to suspect that all ignition coils usually hit the same general resistance specs so they've all been consolidated into ONE product from "over there". Only the connections/terminals might be manufacturer-specific, I suspect.

I don't know if my suspicions are true and accurate, but it wouldn't surprise me if they were.

Regards,

NTX5467

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