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Beastlikethat1

Alternator charging but battery is not?

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Hey everyone so I'm having a strange issue and I just want to make sure I test everything before throwing more money into my 1977 Datsun 620 Pickup. So the alternator went out in it (luckily I made it home) and you could clearly see where the charge wire burnt along with the nut/ inside of alternator. Replaced alternator with Carquest 14105A and everything went on easy but it isn't charging. Continuity is good between positive terminal and alternator B terminal and battery isn't being charged; BUT if I take off the charge cable from the B terminal it's getting 14V, put it back on it's back down to 12.2 while running (new battery as well). Would you all think voltage regulator as culprit? Also the charge light is on inside the truck as well.

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Does the 77 have an external regulator?

Not sure when they changed over....

If so I would make the change to the internally regulated altenator ....

I went through a similar thing wasting money.... buying 2 different alternators and a new regulator, plua trying and old one, never changed properly...

Once I when to internally regulated all problems solve, perfect voltage....

I followed this recommendation,  should work on an L20B....

 

Screenshot-20190207-082230-Gallery.jpg

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'78 was the year internally regulated alternators started being used.

 

I hope you kept the old alternator until you were sure that it was the problem and not just a burnt wire, loose battery cables, bad ground or bad regulator.

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On 2/7/2019 at 8:33 AM, datzenmike said:

'78 was the year internally regulated alternators started being used.

 

I hope you kept the old alternator until you were sure that it was the problem and not just a burnt wire, loose battery cables, bad ground or bad regulator.

 

I turned the old one in as a core sadly but as I said the inside and outside where black from burning around the charge terminal. Anyways I'm starting to wonder if my truck was converted to internally regulated. Where would the regulator be? Sod6Gnl.jpgctvVudH.jpg

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I figure so, there's a round connector near the battery that's been cut and gotten rid of but I'm not sure what was there. Those two relays or whatever they may be were under a black plastic cover which.

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Yeah, probably the round connector top left by the fuel regulator, where the harness enters the cab

Edited by thisismatt

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10 minutes ago, thisismatt said:

Yeah, probably the round connector top left by the fuel regulator, where the harness enters the cab

So the voltage regulator that large black unit? I just didn't see any online that looked like that.

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1 minute ago, thisismatt said:

No, isn't there an unused plug up above it?

On 2/7/2019 at 8:33 AM, datzenmike said:

 

Ah yes there is; there is another one like it in another spot that's also unused. So I'm assuming I'm not missing anything and this truck was converted to internal regulated possibly, and I bought a externally regulated alternator and maybe that's why I'm not getting a charge?

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Yeah, but the correct jumping would have needed to be done.  Usually you do it at the external regulator instead of hacking up the rest of the wiring.

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Probably converted to internally regulated alternator, so get on for a '78 or '79 and you should be OK.

 

Sod6Gnl.jpg  

 

The external regulator would be on that vertical face behind the disconnected negative battery clamp and above those two black harnesses wrapped in tape. 

 

 

ctvVudH.jpg

 

 

The disconnected plug is for the headlight relay. The relay with the green wires beside it is the horn relay. The black box is likely the detector for the EGR. After 30K??? it turns on the warning light on top of the dash to remind you to clean it. The EGR not the box.

 

 

WHY THE FUCK is there a fuel pressure regulator on that fuel line!!!! Someone has installed an electric pump? That fuel filter was NEVER intended to hold pressure. Get that fixed right away. Put the pump between filter and the carb.

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11 hours ago, datzenmike said:

 

Probably converted to internally regulated alternator, so get on for a '78 or '79 and you should be OK.

 

Sod6Gnl.jpg  

 

The external regulator would be on that vertical face behind the disconnected negative battery clamp and above those two black harnesses wrapped in tape. 

 

 

ctvVudH.jpg

 

 

The disconnected plug is for the headlight relay. The relay with the green wires beside it is the horn relay. The black box is likely the detector for the EGR. After 30K??? it turns on the warning light on top of the dash to remind you to clean it. The EGR not the box.

 

 

WHY THE FUCK is there a fuel pressure regulator on that fuel line!!!! Someone has installed an electric pump? That fuel filter was NEVER intended to hold pressure. Get that fixed right away. Put the pump between filter and the carb.

Yes there is an electronic pump, 8PSI and o have Mikunis so I have it dialed down to about 2-3psi. Would you say 8PSI is way too much for that fuel filter? I never thought of that thanks for the heads up.

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The fuel filter is designed to have fuel sucked through it,  not have any pressure at all let alone 8 PSI. Easiest would be to get one of those EFI stainless steel filters just to be safe. If that plastic filter ever fails you could loose the car or worse......

 

You could move it, the filter,  between tank and pump or move the pump between the filter and the carb.

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Unless Im missing something its after the fuel regulator anyway. So I think your fine.

 

Now for volt reg look at photos of the round connector and find that. or where you think it might be and maybe look for some jumpered wires. Most if they convert to  IR TYPE ALTERNATOR. most time cut the volt reg off and them jumper the wires and plug it in to the harness

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It's true what Mike said though, all the filters used on the trucks till at least the 1981 Datsun 720 were made to have the gas sucked thru them, they were not pressurized, but I am guilty of the same thing and have been using the stock 521 plastic fuel filter for several years with electric fuel pumps on my 521 work truck.

My system does not dead end at the carbs though, I have had a return line to the tank and I made my own restriction piece with a 1/16th inch hole, I doubt I have a lot of pressure in my lines, but it runs properly so I have not changed anything.

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53 minutes ago, banzai510(hainz) said:

Unless Im missing something its after the fuel regulator anyway. So I think your fine.

Look at the pic closer, his filter is before the regulator not after 

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I'm confident it will work, but in good conscience what if the worst happened and I didn't say something? Easy enough to move it before the pump. AND there should be a filter before the pump anyway to keep trash out of it. Change every 2 years. Max.

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My old post from 2007 mentions ImportedCarParts.com which now leads you to a malware website. Don't go there!

 

http://www.importcarparts.com/  is a valid parts supplier but they do not have Alternators for the Datsun 200SX. In fact, they hardly have anything for older cars at all.

 

Rock Auto is the place to go for Datsun parts. They do not list BOSCH, but they do have a REMY alt part 1403 listed as a 60amp rebuild for $57. This could change in the coming years.

 

Bosch part number is AL241X if you can find it direct from Bosch or your local parts store. (60 amp, internal reg alt)

 

F400010049BOS.JPG

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Ended up getting an internal regulated rebuilt 35 amp and will eventually get a higher amperage alternator! Also I got an 80 psi fuel filter (per Datzenmike's advice). Last question is that EGR clean reminder module, can that simply be removed and unplugged? Of course EGR stuff isn't hooked up anyways sense I can 44PHH's so I figure it can be I just don't want the EGR light to be on. Thanks!

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Absolutely disconnect and remove if you want.

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