Could use some help diagnosing this issue(1970 510 w L20B)

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B^2
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Could use some help diagnosing this issue(1970 510 w L20B)

Postby B^2 » 16 Jun 2016 12:34

ook the Datsun to work yesterday and had some issues that I was hoping people could help me figure out. It's a 1970 510 with an L20B and a dog leg 5 speed.

Was coming down a slight hill and the car just lost power, I was in gear at the time but no response from the gas or switching gears. Had to coast to a stop. Keep in mind, my volts were showing solidly in the green at the time. I go to restart it and the volts are not right on the edge of yellow/red. Couldn't get the engine to catch until I used jumper cables, at which point the volts immediately go into the green.


Trouble shooting it, I know it's not the battery because I replaced it last year. Fuel gauge shows a quarter of a tank so I don't think it's a fuel problem either. Pretty sure it's the alternator in which case I'll need a recommendation on what to replace it with.
Cheers,
Will
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RMS
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Re: Could use some help diagnosing this issue(1970 510 w L20B)

Postby RMS » 16 Jun 2016 13:07

does your dummy light come on with ignition turned on and not running ? an intermittent connection to the dummy lamp (10 ohm resister) will cause charging issues. also never assume because its new that its any good.
two_68_510s wrote:I guess our donkeys are quicker then your sled dogs!

B^2
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Re: Could use some help diagnosing this issue(1970 510 w L20B)

Postby B^2 » 16 Jun 2016 13:12

Yes, I believe the dummy light comes on.

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bertvorgon
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Re: Could use some help diagnosing this issue(1970 510 w L20B)

Postby bertvorgon » 16 Jun 2016 14:06

I would get a "LOAD" test done on that battery, which would point out a bad cell.

New is not necessarily good.
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datzenmike
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Re: Could use some help diagnosing this issue(1970 510 w L20B)

Postby datzenmike » 16 Jun 2016 16:00

Non charging won't cause what you describe.

Can only be lack of fuel.... a full tank does not mean you don't have a fuel delivery problem... or electrical.... new battery means little.

ELECTRICAL... can be sudden or prolonged stuttering before quitting.
As stated your car will run a long time without alternator charge.

It would have to be an interruption of power to the coil to shut it off. Did everything shut off? This would indicate the fusible link as everything has to go through it.

If just the ignition maybe a loose wire or loose/corroded/bad fuse

Do you have the stock distributor? If EI dizzy and a points the coil it can overheat and shut off.

If points maybe time to file or replace.


FUEL.... almost impossible to shut off suddenly. Usually very poor running, may backfire before finally quitting as the carb empties.
Do you have an electric fuel pump? look for loose wire.

Stuttering specially under load is likely a clogged fuel filter where the carb empties faster that the pump can replace the fuel.

Take the fuel line off the output side of the pump and direct into a suitable container. Take the coil wire off and have someone crank the engine over. You should see strong surges of fuel if the pump is working normally. Check filter first.
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs

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okayfine
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Re: Could use some help diagnosing this issue(1970 510 w L20B)

Postby okayfine » 17 Jun 2016 06:02

OP, you're going to have to be more descriptive and exact in your posts, because that's ALL we know about your symptoms.

If you went from 100% normal, running engine to engine dead in a split second, that's one thing. If you were in gear and the engine was sputtering and you tried to give it gas and nothing really happened but the engine was still doing something but not really anything...that's another.

I have had fuel issues like MIke describes above where you get some notice you're running out (even if there is gas in the tank) and I have also had fuel issues where everything is fine and in a snap the engine is dead. Especially on a straight freeway section, it is possible to run out of fuel without sputtering - I've done it. My cause was clogged fuel line, but...

How long have you had the car? Have you done ANY work on it recently? I would put little faith in your gauge set since the gauge on the right (oil pressure) is reading off the stop. In any case, volts can be lots of things and not the battery (much more likely a wiring issue to the gauge, but also a wiring issue somewhere else).

You'll need a VOM to do some exploratory testing. You'll also need to do the fuel check test Mike outlines above. You should also have a good wiring diagram and a service manual reference. Reply back with exactly what you have done, the exact results (measured x, got y reading, no "I checked everything and it was fine").
Because when you spend a silly amount of money on a silly, trivial thing that will help you not one jot, you are demonstrating that you have a soul and a heart and that you are the sort of person who has no time for Which? magazine. – Jeremy Clarkson

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two_68_510s
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Re: Could use some help diagnosing this issue(1970 510 w L20B)

Postby two_68_510s » 17 Jun 2016 08:03

To follow up on what okayfine mentioned, why are you attaching so much importance to the voltage output?
Joel

2 '68 510 2 door sedans
'95 240SX
74 Jensen Healey

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