Mechanics

DOESNT START AN WHEN JUMPED IT STARTS BUT DOESNT STAY RUNNING

1966 Plymouth Fury • 61,208 miles

318 engine I have replaced starter relay an battery im having problems getting it started but once I jump it it starts after awhile but when I shut it off it just clicks other problem not sure if related but when I pull out my drive way it dies out but if I keep the engine reved it wont die out any advice would be helpfull btw it was running great after changing the battery then my dumb brother messed with the carb mixture screws now it wants to die if that helps ive tried to reajust back but idleing to high new fuel pump was installed hints the brother messing with stuff
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Dream66
April 28, 2012.



Start with the mixturescrews. Turn them in till they bottom out and then turn them out 3 turns. That is a good start. Start it up and adjust out or in till it runs good on each screw.

Could have a bad starter motor with the clicking.

Roy

ASEMaster6371
Apr 28, 2012.
Ok on screws ill try that but starter turns over after sitting on a charger for about 10 mins

Tiny
Dream66
Apr 29, 2012.
Hi guys. From your other post you should also be looking at the charging system first. Since it cranks okay after charging the battery, you likely don't have a starting problem but you could have a charging problem. Use an inexpensive digital voltmeter to measure the battery voltage before starting the engine and again with the engine running. Engine off you should find 12.6 volts for a fully charged battery. If you have closer to 12.0 volts, the battery is good but discharged. With the engine running, you must have 13.75 to 14.75 volts. If it stays around 12.0 to 12.6 volts, suspect worn brushes in the alternator. If it's just a little below 13.75 volts, suspect the voltage regulator. Your car has a mechanical regulator unless someone modified it to the 1970 and newer electronic regulator. The mechanical ones can be adjusted but it's been a real long time since I played with one so I'd have to dig out a service manual.

Also, a common cause of intermittent failure to crank is a rusted ground wire at the body. The fat negative battery cable must be bolted to the engine. There will also be a smaller wire that bolts to the inner fender. I had a '69 Barracuda a long time ago that had a loose and rusty connection at the fender. The only way for all of the current used by the rest of the car's lights and ignition system to get back to the battery was through the fat battery cable on the engine. But the engine is mounted on rubber mounts that isolate it electrically. I finally figured that one out when the throttle cable started to smoke and melt! That was the only path the current could find. Once the ground wire was fixed, the starter and starter relay worked just fine.

Caradiodoc
Apr 29, 2012.
I went ahead an got the alt tested out an its not the right ampage for the battery I have turns out its the original alt so replacing it would be a good idea on my behalf but I tested cables an ampage an everything was ok tilli tested running running it was holding at 12.7 so im going to replace alt an let you know the outcome thank you for your advice everyone this is my first classic an im way over my head I guess

Tiny
Dream66
Apr 29, 2012.
Alternator amperage has nothing to do with the battery size. Just like the cold cranking amps (CCA) rating of the battery indicates the maximum current it can deliver, the output rating of the alternator indicates the maximum it can produce. That's just it for both of them; the maximum. Alternators are self-regulating in that respect. They simply won't produce more current than their design allows for.

The standard alternator was rated at 33 amps. If it has a dual pulley, it was made for cars with air conditioning and those were designed for 55 amps. I don't recall there being any larger alternators in the '60s, but starting with the 1970 models there was also a 78 amp unit. All of those are puny by today's standards but back then there were no computers, no electric fuel pumps, and no electronic fuel injection. It was rare to need 33 amps to run all the lights, heater fan, and wipers with a little left over to recharge the battery. When rebuilders got a hold of these to repair, it didn't cost any more to rebuild the 55 amp units so they often just did those. That one alternator could be used in any application so they had fewer part numbers to stock on the shelves. If you have the dual pulley but the car doesn't have air conditioning, put the belt on the rear groove. There is no issue with using a larger alternator. If the demands of the car's electrical system is 30 amps, that's all either alternator will deliver; no more. If the demands are 45 amps, the smaller one won't keep up and some current will come from the battery. That won't hurt either as long as that's a temporary condition.

Before you replace the alternator, look for the smaller wire attached to the back of it. With the engine running, use a piece of wire to connect that wire right to the bolted-on output wire. There might be a black rubber cap you have to move out of the way. Monitor the battery voltage while you do this and do not raise engine speed, at least not very much. This full-fields the system to make the alternator run wide open. Only the battery will be holding system voltage down to a safe level. What you are doing is bypassing the voltage regulator. If battery voltage goes up a bunch, the alternator is working. If it does, remove that jumper wire, then measure the voltage on that smaller wire. If it's fairly high, say 8 - 10 volts, the regulator is trying to run the alternator but without much success. That would be the time to seek a mechanic with a professional load tester. If one diode is bad inside the alternator, you will lose exactly two thirds of its output capacity and it won't come close to keeping up with demand. Rather than retyping this all over again, you might want to check out these pages:

http://randysrepairshop.net/charging-systems.html

http://randysrepairshop.net/charging-system-theory-of-operation.html

You're the second person to be working on this 1960 - 69 system recently so I'll try to add a page specific to it soon. You have a "B" system when it comes to full-fielding it. The 1970 - 89 electronic system is an "A" circuit. It works the same way but it's even easier to full-field.

For reference, the 1960 - 69 alternator can not work on a 1970 and newer car but the newer model can be used on '69 and older cars by grounding one field terminal. Rebuilt alternators used to come with a metal washer that could be installed in place of the fiber insulating washer on one field terminal to make it work on the older cars. If you see two field terminals and one doesn't have a wire attached, that's why.

Caradiodoc
Apr 29, 2012.
Ok I bought a new meter an now when running its hopping to 15.25 an off sitting at 12.6 but after shutting it off it just clicks after waiting about 5 mins im dumbfounded by this cause I can drive it to the store an back with no problems but once I shut it off after a few mins it just clicks maybe alt is bad but before I go buy one I want your advice if you have the time also I reran all the grounds with new wire an sanded down the areas that needed it

Tiny
Dream66
May 1, 2012.
You either have a bad battery, it's not getting recharged, or there's a bad connection. 15.25 volts is a little high but nothing to write home about, and that suggests the battery is getting recharged. The 12.6 volts says the battery is okay, so lets start out on the assumption there's a cable or connection problem.

When it just clicks, don't wiggle or tug on anything because we want it to stay in the bad state so we can find the cause. Measure the battery voltage again right on the posts. If it's still 12.6 volts, move the meter probes, one at a time, to the cables, then down the line to find the first place where the voltage drops. You'll have to take those measurements when current is being drawn from the battery. That will make the bad connection show up. You can try that by just turning on the head lights, but if that's not enough current draw to make the bad connection show up, you'll have to take the readings while a helper tries cranking the engine. What you're looking for is called an undesirable "voltage drop". For the complete procedure, take a look at this page:

http://randysrepairshop.net/voltage-drop-tests-in-a-high-current-circuit.html


Caradiodoc
May 1, 2012.
I wanna thank you I found that one of the alt cables were bad it looked good till I tugged on it an snap it went after fixing that ive had nomore problem an to the person that helped with the mixture screws that worked great the car runs great now thank you all again

Tiny
Dream66
May 1, 2012.
Dandy news. Happy to hear it's fixed.
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Caradiodoc
May 1, 2012.

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