Car Wont Start
Thread Starter
Burning Brakes
Joined: Jun 2007
Posts: 1,062
Likes: 10
From: Dallas TX
Car Wont Start
I am trying to start a recent purchase that has been sitting for 15 years in a garage. I replaced the battery, coil, plugs, cap, rotor and points. The car will turn over no problem but not getting any spark.
I have taken my multi meter and got the following readings:
12v at the battery--good because its new
8v at the input side of the resistor
4v going out of the resistor
Same 4v at the positive side of the coil
I even stuck my multimeter inside the plug wire from the coil to the distrib at the distrib side--same 4v.
Any help would be appreciated.
I have taken my multi meter and got the following readings:
12v at the battery--good because its new
8v at the input side of the resistor
4v going out of the resistor
Same 4v at the positive side of the coil
I even stuck my multimeter inside the plug wire from the coil to the distrib at the distrib side--same 4v.
Any help would be appreciated.
Drifting
Joined: Apr 2011
Posts: 1,632
Likes: 401
From: Australia
Should have ~ 12v @ the input side and ~ 8-9v @ the output side, 4 volts is not enough for a spark.
You may also have voltage drop through the IGN & bulkhead connector only giving you 8v @ the input side.
Replace (or just bypass for now) the resistor and get some fresh fuel in it as well
Le Mans Master
Joined: Feb 2008
Posts: 6,528
Likes: 1,939
From: Folsom CA
I agree with Any Chevy, fully drain the fuel tank and system of old gas. 15 years old fuel can cause major internal engine problems to your valves. It makes them gum up and stick in the valve guides. For a few bucks in fuel it is money well spent to drain and replace.
As mentioned a 12v jumper wire to the pos side of the coil should get it spark. This will only allow you to attempt a start with spark. You will need to backtrack the electrical and find the voltage drop issue.
As mentioned a 12v jumper wire to the pos side of the coil should get it spark. This will only allow you to attempt a start with spark. You will need to backtrack the electrical and find the voltage drop issue.
Drifting
Joined: Apr 2011
Posts: 1,632
Likes: 401
From: Australia
Team Owner
Joined: Aug 2007
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Army
No. Jumper from the + battery terminal to the + side of the coil and see if you get spark -- running for a while like that won't hurt a thing (not meant to be permanent though). If you only have 8V at the resistor then that is certainly part of the problem. Here is a dumbed down circuit drawing to show you how things are connected. The ignition switch should deliver a full 12V to the ballast resistor..
Team Owner
Joined: Jul 2006
Posts: 22,200
Likes: 4,187
From: Kannapolis NC
I don't see why you'd have 12v at the battery and 8v on the 12v side of the ballast resistor. Something must be shorted and drawing it down. Did you also change the condensor? Maybe the wire from the ignition's connection is corroded and dropping the voltage. When the igniton is turned to start, you should have full battery voltage at the + on the coil (fed from the starter solenoid)and then drop to about 8v when released to the run position. Disconnect the wire from the + on the coil and see if the voltage goes to 12v on the ballast. That should at least tell you if you have 12 v feeding from the ignition switch to the ballast resistor.
Team Owner
Joined: Jul 2006
Posts: 22,200
Likes: 4,187
From: Kannapolis NC
Another thought, where did you read the battery voltage? Try reading from a chassis ground and to the 12v contact on the starter in case the negative wire is not making good connection to the chassis, or the positive battery cable is not getting a good contact. You really should be reading 12v on the bottom side of the ballast.
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Team Owner
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Army
Dollars to doughnuts that its a bad/corroded ignition switch/wiring or a bad/corroded ground. No use even monkeying with fuel until this issue is resolved...
Do this (without ANY jumpers anywhere):
1) Measure from the - (negative) battery post to the "input" side of the ignition coil and if you don't get 12V you have a problem on the 'hot' side of the circuit (ignition switch/wiring/etc.)
2) Jumper from the battery to the + side of the ignition coil then measure from the + ignition coil to a bolt at the valve cover (the usual place for a C1 ground). If you don't get 12V you have a grounding problem.
Do this (without ANY jumpers anywhere):
1) Measure from the - (negative) battery post to the "input" side of the ignition coil and if you don't get 12V you have a problem on the 'hot' side of the circuit (ignition switch/wiring/etc.)
2) Jumper from the battery to the + side of the ignition coil then measure from the + ignition coil to a bolt at the valve cover (the usual place for a C1 ground). If you don't get 12V you have a grounding problem.
Last edited by Frankie the Fink; Jan 5, 2012 at 09:52 AM.
Burning Brakes
Joined: Jun 2010
Posts: 942
Likes: 3
From: Louisville KY
Dollars to doughnuts that its a bad/corroded ignition switch/wiring or a bad/corroded ground. No use even monkeying with fuel until this issue is resolved...
Do this (without ANY jumpers anywhere):
1) Measure from the - battery post to the "input" side of the ignition coil and if you don't get 12V you have a problem on the 'hot' side of the circuit (ignition switch/wiring/etc.)
2) Jumper from the battery to the + side of the ignition coil then measure from the + ignition coil to a bolt at the valve cover (the usual place for a C1 ground). If you don't get 12V you have a grounding problem.
Do this (without ANY jumpers anywhere):
1) Measure from the - battery post to the "input" side of the ignition coil and if you don't get 12V you have a problem on the 'hot' side of the circuit (ignition switch/wiring/etc.)
2) Jumper from the battery to the + side of the ignition coil then measure from the + ignition coil to a bolt at the valve cover (the usual place for a C1 ground). If you don't get 12V you have a grounding problem.
Burning Brakes
Joined: Jun 2010
Posts: 942
Likes: 3
From: Louisville KY
True, but it could be that he meant there is no "igniting of gas by a spark," iow, no sputtering. Is there a way to tell whether there is truly no "spark" going on in the combustion chamber? I would think it could be absence of spark or fuel.
Team Owner
Joined: Mar 2003
Posts: 26,118
Likes: 1,874
From: Greenville, Indiana
The low voltage on the switch side of the ballast is probably because the points are closed. Maybe the reason for no spark is there is no point gap or a wire is shorted inside the distributor.
Easy check. Put a test light on the - side of the coil and spin the engine over. You should see a bright flash on/off/on/off. If you see a bright/dim/bright/dim, your problem is inside the distributor. Assuming you have the former condition, your coil should fire. If it doesn't, you may have a defective coil.
Team Owner
Joined: Jul 2006
Posts: 22,200
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From: Kannapolis NC
I think we need to wait for the original poster to let us know what he's found from the suggestions offered. Based on what he has already tried, my money is on a bad connection, either ground or ignition, or a shorted condensor. I'd certainly fix my 12 volt and spark issue before further troubleshootiing.
Thread Starter
Burning Brakes
Joined: Jun 2007
Posts: 1,062
Likes: 10
From: Dallas TX
I didnt mention that this is a FORD so that could be the main problem. I have bypassed the fuel line so it shouldnt be a fuel issue--primed the carb prior to starting.
I will try all of the suggestions above on voltage readings and post back. I bought new points and gapped per specs.
I measured from the negative side of the battery to the + side of the coil and still got 4v. I will try Frankie's suggestion #2 and report back. I measured all the volt readings above from both the battery ground and a ground on the chassis--same readings.
Thanks for all the help.
I will try all of the suggestions above on voltage readings and post back. I bought new points and gapped per specs.
I measured from the negative side of the battery to the + side of the coil and still got 4v. I will try Frankie's suggestion #2 and report back. I measured all the volt readings above from both the battery ground and a ground on the chassis--same readings.
Thanks for all the help.
Le Mans Master
Joined: Oct 2000
Posts: 8,897
Likes: 1,357
From: Santa Ana CA
Disconnect the wire from the ballast resistor to the distributor and, with the key "on," read the voltage on the wire at the ballast resistor on the "firewall side" of the resistor (the remaining wire). This should reflect the full battery voltage.
If not, your problem would lie in the ignition switch/underdash wiring.
If not, your problem would lie in the ignition switch/underdash wiring.
Thread Starter
Burning Brakes
Joined: Jun 2007
Posts: 1,062
Likes: 10
From: Dallas TX
I know...my buddy who is a die hard GM guy scraped his knuckles while helping me try to get it started on Tuesday. He called today to tell me his hand was infected.
As a follow up, the insight, knowledge, etc of not just corvettes but old cars in general on this forum compared to the mustang forum I'm on is dramatically better.
As a follow up, the insight, knowledge, etc of not just corvettes but old cars in general on this forum compared to the mustang forum I'm on is dramatically better.
Last edited by TX63CONV; Jan 5, 2012 at 05:11 PM.
Drifting
Joined: Jun 2005
Posts: 1,747
Likes: 192
From: nj
A long, long time ago I had the exact same problem.
turned out to be the wrong spark plugs. champ j12y vs uj12y or some such mix up. could not believe that was the problem. Had everything apart 3 times with multiple substitutions. Don't suppose that problem will ever occur ever again anywhere on the planet earth but it drove me insane.
turned out to be the wrong spark plugs. champ j12y vs uj12y or some such mix up. could not believe that was the problem. Had everything apart 3 times with multiple substitutions. Don't suppose that problem will ever occur ever again anywhere on the planet earth but it drove me insane.