1978 Chrysler Newport wont fire - voltage drop.

FPJ

New Member
Joined
Jul 20, 2016
Messages
7
Reaction score
1
Location
Welland
1978 Chrysler newport. Took the car for an hour drive spent 3+ hours at the drive inn and the hour drive back drive. The car ran fine. Car will only start when boosted now. Runs fine at 14+ volts when running.
Unplugged battery, charged to 99% at night. meter read 12.96 - 12 hours later meter read 12.26. Put in key, turn on without cranking car and voltage instantly drops to 10.9 or 11.2.
Turn off key, voltage climbs back to 12.21 and has been steadily there each time I've tested.
cleaned wires and got a new battery cable terminal as the old one was looking nasty. Still same problem. I don't think its the battery or the alternator, but I could be wrong? I'm still learning as I go. Could it be the voltage regulator or Electronic ignition module? (bolted on the firewall) Im hoping one of you pros can put me in the right direction. thank you.
 

mopar440

Well-Known Member
Joined
Oct 17, 2018
Messages
714
Reaction score
386
Location
St paul
Something is drawing heavy on key up

That's gonna be tricky to find. One way is to turn the key on, and start feeling for heat on a coponant/wire. Becareful tho, something could get hot

Or disconnect stuff one at a time and look for voltage yo go back up
 

Davea Lux

Old Man with a Hat
FCBO Gold Member
Joined
Mar 27, 2017
Messages
8,913
Reaction score
8,069
Location
Cornelius Or
As noted take the battery out had have it tested. I suspect that the battery may have a shorted cell. If it checks out ok, start looking for a short some place else. Remove the positive battery cable and run a draw test between the cable and the battery post to see if something is creating a draw with the car off. You can use a test light for that. (Remove the fuse from the clock) Most auto parts should have a load tester you can rent or borrow to see what kind of load the starter is trying to draw when the attempt is made to start the car.. FSM has the load numbers.

Dave
 

mopar440

Well-Known Member
Joined
Oct 17, 2018
Messages
714
Reaction score
386
Location
St paul
I was assuming he tested the battery, but your right, he may not of
 

CBODY67

Old Man with a Hat
Joined
Mar 27, 2011
Messages
7,250
Reaction score
4,423
There might be ONE cell that's now marginal, but could be on the way to being non-functional.

Is the ignition control box the original or ahs it been "upgraded"? Some of the "upgrade" boxes take more intial volts to fire the plugs than an OEM box will, by observation. Years ago, we were at a weekend cruise event. A nearby E-body would not start. It was spinning over fast enough to start, but would just spin over. When a pair of booster cables was attached (from another Mopar), it fired immediately and ran just fine. Which is why I'm posing that question.

Take care,
CBODY67
 
Top