Plymouth Fury

1969 Plymouth Fury Electrical / Lighting Systems Dimming Happens always Always

My '69 Fury loses electrical power when idling at low speeds and slowing or stopping. Headlights, blinkers, wipers, heater, or whatever I've got turned on dim or slow as applicable almost to the point of shutting off. This happens wether I'm running just the headlights or all the accessories, warm or cold. The alternator and voltage regulator are brand new, and the voltage from the alternator, through the voltage regulator, starter, and battery all seem fine. Any ideas?

Hi:
Sounds like you got a bad ground. Might want to check the ground connection from the engine to the body and also your connection at the block. If needed you can add a ground strap from the engine to the body and this will help the ground circuit. Glad to hear that there is someone out there that sticks to the good but the oldies. Good Luck Les

I thought the grounds were good last time I checked, but I'll take another look. In case I've got a solid ground, any other ideas? I'm clueless when it comes to cars, and in retrospect this was probably a bad project to take on!

Hi again;
Only other thing I can think of is a bad hot wire. But this does not sound logical due to the fact that you stated the charging system was tested and showed up good. As your comment about a bad project. It's actually a good project and once figured out you will benefit from it. Any more Help please feel free. Thanks Les

1969 Plymouth Fury Electrical / Lighting Systems Dimming Happens always Always

Hi, all.

Okay, I've got a problem with my '69 Fury. When I'm sitting at idle or slowing down, or pretty much anytime I've got my foot off the gas, I start to lose power to my lights/turn signals/wipers/heater/whatever. No matter how little or how many things I'm running, everything dims or slows as applicable almost to the point of not working.

Here's what I've done so far to try to fix the problem:

Brand-new battery
Brand-new alternator
New starter (old one had a short)
New voltage regulator
New battery ground cable
I replaced the slightly frayed engine block ground with a new braided ribbon-type grounding strap.

None of this seems to help.

Any ideas?

Hello, Is there a ground wire from the battery to the body as well as the negative cable bolting to the engine block? (Engine block to battery doesn't count here)

Roger

Roger,

No, there's no ground from battery to body. There's one from the battery to the engine block, and one from the engine block to the chassis.

I recommend you add a ground from the battery to the body. Use a wire that is at least 10 gauge or larger.
Be sure the new ground connects to a clean spot on the body. Improve the cleanliness of other grounds if needed. Whenever a star washer is used at a ground connection it must stack between the wire terminal and the surface that the ground connection bolts to.

Check your engine idle speed to see if it is correct. Too slow an idle RPM spins the alternator a bit slow and effects output. Is there an upgrade alternator (higher output) available for your car?

One more thought is the size of the alternator pulley. If it can be changed to a smaller diameter the alternator will spin faster. Proper belt tension is important too.

Roger