Weird power issues

[datzenmike]

Ummm it's not really a short. A short is a short-cut path the ground without going through an electrical accessory like it's supposed to. If you have a short a fuse will blow or you will have a fire. I don't think this is the case here. Most likely it's an open or break in the circuit where power isn't getting through. Could be an intermittent problem with the ignition switch or the fusible link.

[converted_to_datsun]

I'll check those too. I think it might be the battery or a drain associated with the headlights. Seems to happen after driving with the lights on for awhile and goes away after I drive it during day light with no headlights on for awhile

[wayno]

The battery can turn an engine over enough to start it and still be bad if the engine starts easily.

You say the radio turns off after a while when you turn the headlights on, and the radio comes back on after you drive for a while with the headlights off, this sounds like either a alternator or battery issue.

Check the main alt. line going from the back of the alt to the starter post, make sure this is not corroded or starting to fray on the ends.

Have the battery load tested as suggested above by Draker.

Keep in mind that a bad battery will destroy the armature in the starter, it will turn over slower and slower till it burns itself up.

[LenRobertson]

I thought I'd post what seems (hopefully) to have fixed my weird electrical problem. May not help converted to datsun, but someone else chasing gremlins may read this and see a fix.

 

I unplugged the wires going into the ignition switch and plugged them back in and that seemed to make the problem worse. I can't even remember all the odd things it was doing with idiot lights off or on, starter working or not, power at the coil or not. So the guessed the switch was the problem. Swapped in a different switch (old used 510 one, so no way of knowing if it was good), and that didn't help.

 

A friend stopped by and as I turned the switch to different positions, he found a relay up front that was clicking. On the '72 510, this is the front relay on the passenger side of the engine bay, one with 6 wires going into it. I cleaned the spades on the plugin really well.

 

Then I went to the sleazy temporary wiring I did when I hooked up a matchbox dizzy. Originally when I bypassed the ballast resistor, I moved both of the spade terminals on the resistor together under one of the resistor nuts, then plugged the two wires onto the spades. The idea was to hook the two wires together and this did, more or less. I found one of the push-on wire connectors to be pretty loose on the spade, so I connected the wires with a short jumper wire I had laying here. Now have much better connection through the wires that power the coil.

 

I don't know which of the fixes solved the problem, but for the first time, the engine starts right up when I crank it. Before, it was kind of a battle to get it to start. I've also been working on the idle circuit of the carb this week, so it may be a combination of all three makes for better starting. But I suspect the tarnished relay connection was the main problem. It is easy enough to clean and see if it helps. With 6 wires going to the relay, it must control a couple of circuits, but I'm not sure which. I can't find a similar relay on any 510 wiring diagram I have.

 

Len

[converted_to_datsun]

So I got the battery tested and it was fine... Then got the alternator tested and the internal voltage regulator went out. The alt was about a year old. I picked up a 280 zx alt but was way too big diameter so ended up with a stock 35 amp... At least it's fixed now

[LenRobertson]

I found this link in another thread just now:

http://community.ratsun.net/topic/18218-how-to-install-a-saturn-alt/

It refers to doing the Saturn alt into a 620, if at some point in the future you feel the need for more amps. I'm curious what 35 amp alt you have. I always thought these are external regulators, but there well may be a IR version. Or maybe you have blown diodes in an external regulated alt. So much of this stuff I'm still learning on a daily basis.

 

When I went to install the much bigger 280Z alt in my 510 I thought there was no way I could get it in there without removing the oil filter and maybe bottom radiator hose. But I kept kind of twisting it around and all of a sudden it slipped past the obstructions into place. But a 620 may be different.

 

Len

[Dat Lurka]

< winner winner chicken dinner

[converted_to_datsun]

The 280 one bolted up but was soo big there was no adjustment left and even if there was I'd shred a radiator hose. I think mine was just a really big one

[datzenmike]

When I went to install the much bigger 280Z alt in my 510 I thought there was no way I could get it in there without removing the oil filter and maybe bottom radiator hose. But I kept kind of twisting it around and all of a sudden it slipped past the obstructions into place. But a 620 may be different.

 

Len

 

Just bellow the 620 alternator is a grease fitting for the idler arm. Not much clearance there.

 

To fit the larger (size) 50/60 amp 720 alternator I used a 280zx lower rad hose fitting to the timing cover. It's swept back at a sharper angle and holds the rad hose away from the larger diameter alt. I also used a 720 alternator-to-block mount which lifts the alt. about 1/2" and a slightly shorter belt. It worked but I have to install the belt on the pulley first, and then bolt the alternator to the bracket on the block.

[izzo]

those smaller 720 alts are handy dandy! and 50amp isn't bad. I run one in the B... Then just did the IR alt swap on the harness, but yours is already IR....

[Laecaon]

Silly trucks. Needing the ZX water inlet. Im not really sure whats different, but I know my 510 took a ZX alt super easy.

[izzo]

because race car.

[datzenmike]

Silly trucks. Needing the ZX water inlet. Im not really sure whats different, but I know my 510 took a ZX alt super easy.

 

Just bellow the 620 alternator is a grease fitting for the idler arm. Not much clearance there.

 

My 710 sedan has an S13 KA 90 amp alternator. Had to mod the mount-to-motor bracket but the 710 pulley and belt fit perfectly. Well ir should as the 710 alt is a larger 50 amp to begin with same as your 510.

 

My 710 goon will have an '02 Maxima alt when I get around to it. The pos. output cable is as big as the 710 battery cable!!!!

[Laecaon]

Oh yes, I remember that now.

[datzenmike]

:D

[converted_to_datsun]

Yea mine was hitting the lower water inlet otherwise it would have fit. I guess I don't use that much power so 35 should be just fine. It runs everything at once and keeps me charged up so I'm happy