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Jarvo2

240z alternator upgrade (instructions w/ pictures)

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    So while digging through my box of parts that the previous owner provided me, I ran across a brand new alternator, which ended up being a 280ZX internally regulated 60amp model. After upgrading to the Pertronix electronic ignition last year, I began to hear that the 240z's voltage regulator and 40amp alternator might not be powerful enough, so I investigated upgrading. All it cost me was the price of a diode ($2 @ Radioshack) as I had all of the other parts already.

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    After removing the voltage regulator I found out why its recommended to go with an internally regulated alternator -- look at how the backing plate has melted!

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    In order to eliminate the external voltage regulator I needed to create a jumper, including a diode to allow the car to turn off when the key is removed. Here is the best diagram I was able to find on the internet (thanks to the user who posted it here first!):

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    I ended up using a spare voltage regulator connector (and kept the somewhat working voltage regulator in one piece in case I ever needed to switch back). This connector then plugs in just like the voltage regulator would.

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    Once installed with the waterproof boot that I had laying around (which fit perfectly), I was able to tuck the jumper harness under the wires and it looks like its always been there.

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    Now that I've been driving on the new alternator without the external voltage regulator I can honestly say the car is running better than it probably did when it was new. This was a great upgrade and should be done by anyone having ignition or performance issues (I thought it was my carburetors, but all along it was electrical issues).

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    Good write up Dave. It would be a good addition to the Technical Articles.

    Chas

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    Thanks. Dave Irwin just pointed out that this is only valid for 70-72 240z's as the 73 with an OEM electric fuel pump needs to be rewired to prevent battery drain.

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    Of course - Dave Irwin was selling the plugs pre-make, to anyone that wanted one - years ago here.

    FWIW,

    Carl B.

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    Terrific writeup. Great pictures too.

    Is the 280ZX alternator the best to use to switch to an internal regulator or is there another more widely used alternator (possibly a cheaper GM or whatever) that will work? I have read going with a GM alternator requires a bracket modification.

    Mike

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    Hi, I have done your swap in my 1973 240z. the swap worked, however my 12v yellow wire on the harness is melting??? What would cause this? Is it the starter wires? could it be multiple problems? how much money to take it to a shop if i dont get answers here? thanks for any input

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    Hi, I have done your swap in my 1973 240z. the swap worked, however my 12v yellow wire on the harness is melting??? What would cause this? Is it the starter wires? could it be multiple problems? how much money to take it to a shop if i dont get answers here? thanks for any input

    The wire is melting due to too much current. With no pictures, meter readings etc., it is difficult to diagnose the problem. It would not be due to the wires going from the battery to the starter. What is your ammeter reading when you're driving the car? How old is the battery?

    Maybe you should try the plug that MSA offers: Motorsport! Alternator Upgrade Adaptor, 70-73 240Z - The Z Store! Nissan-Datsun 240Z-260Z-280Z-280ZX-300ZX(Z31/Z32)-350Z-370Z Parts (Gee, this link looks familiar. ;))

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    The wire is melting due to too much current. With no pictures, meter readings etc., it is difficult to diagnose the problem. It would not be due to the wires going from the battery to the starter. What is your ammeter reading when you're driving the car? How old is the battery?

    Maybe you should try the plug that MSA offers: Motorsport! Alternator Upgrade Adaptor, 70-73 240Z - The Z Store! Nissan-Datsun 240Z-260Z-280Z-280ZX-300ZX(Z31/Z32)-350Z-370Z Parts (Gee, this link looks familiar. ;))

    Yes, but we all learn the hard way. After a few hours of research, i found if i connect 1-5 and 2-3 on the connector, then i had 12 volts at the 2-3 connection... and that is where i put a diode. i found that the 5-6 connection doesnt work for 1973's, and the correct way is 1-5. however, when i connected this way, my voltage needle was on the middle line inside my cars' ampgauge. i dont think im getting the battery charging from the alternator.

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    Did you point the Diode the right way? If not, the alternator won't see the battery voltage.

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    Did you point the Diode the right way? If not, the alternator won't see the battery voltage.

    -yes, the silver line is facing the number 1 pin.

    (update) i disconnected the jumper plug and the voltage regulator. the car runs fine. what is going on? :stupid: i think the car has been rewired. :cry:

    Edited by Nobsz

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    Does your 73 have the Nissan factory-designed electric fuel pump retrofit? That could account for some of the wiring differences you are finding.

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    There is not a pump in my tank i have no gas tank in at the moment (the tank is rusted) And my fuel cell doesnt have a pump. I am only running the stock mechanical one, plus my numbers are too early. Its very confusing, as a deaf man use to own the car and i tried communicating as well as i could. I think he may have rewired the car because, with the regulator unplugged my car should still run with the key off right?

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    If I can find it (and have time and can remember to look), I have the added wiring harness that was used for the electric fuel pump. I can take a picture of it so you can see if you have one in your engine bay.

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    I have this blog saved! I just did the alt upgrade! Seems better. However, I was checking amps and volts at the battery. volts were like 13.80 up to 14.09 i believe. anyways im not worried about that. the amps is what i am concerned about. I installed it and it was like 30~40 amps. then i went for a drive, the car died, i believe it was vapor lock, anyways got back and checked amps and it was like ~50. my question is, is that ok? also im gonna need some help locating the fuseable links on my car as i dont want to overload 40yr old fuseable links.

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    I'm glad my illustration is used for good write up :-)

    Thats a great illustration you made tamo3. Makes it very clear and simple to follow:cool:

    Chas

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    Im totally doing the oil switch so i can have an electrical fuel pump too! im just a little confused on the wiring from the relay. like 87 on the relay. the + wire. does that connect to the inline fuse behind the dash? and from the oil pressure switch, the wiring running from I. did you run that to an existing wire before the fuse or install one? I will have to physically go and look at this stuff soon, trying to get my tach to work and switch to the 280zx dizzy. Ive got some strange wiring going on there. hmp. again awesome write up and awesome illustrations for the ALT upgrade!

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    3ryce:

    For the relay, 87 is the power feed (once the 'system' is working i.e. oil pressure detected, ignition turned on, etc.) which then goes to the fuel pump itself through the green wire behind the radio. I just put a simple inline fuse for an added safety measure. Glad you guys are enjoying my write-ups!

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    Ok, i think i get it. my z actually has a working electric fuel pump with stock wiring, however what i dont like it when i turn it to acc the pump it on. I hope to fix that with the oil pressure switch. Yes i enjoy your blog very much! thanks again for doing that!

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    I'm trying to write a specific instruction sheet for the 73' 240Z ZX alternator conversion that will allow owners to correctly identify the yellow wire on the fuel pump relay pack, located on the passenger side kick panel, and how to cut it, connect to it and run it to an ignition point or oil pressure safety switch.

     

    What I need is a 73' 240Z owner to take a decent picture of the fuel pump relays, there location on the passenger side kick and a clear picture of the yellow wire, that is connected to the relay from the voltage regulator.

     

    Once I can show people where to locate the wire, I can show them how to wire it into a relay, a switch or Oil pressure safety switch to control the relay without draining the battery.  The ZXP or ZX alternator adapter plug that I Still make and sell to MSA for sale through them, CAN be used on the 73's once the instructions are more clear to the average "I don't do electrical" 73' 240Z owners.

     

    So please post pictures of the fuel pump relay(s) and the yellow wire.

    I and everyone else will greatly appreciate it.

     

    Dave

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    On 3/11/2015 at 10:05 PM, Zs-ondabrain said:

    I'm trying to write a specific instruction sheet for the 73' 240Z ZX alternator conversion that will allow owners to correctly identify the yellow wire on the fuel pump relay pack, located on the passenger side kick panel, and how to cut it, connect to it and run it to an ignition point or oil pressure safety switch.

     

    What I need is a 73' 240Z owner to take a decent picture of the fuel pump relays, there location on the passenger side kick and a clear picture of the yellow wire, that is connected to the relay from the voltage regulator.

     

    Once I can show people where to locate the wire, I can show them how to wire it into a relay, a switch or Oil pressure safety switch to control the relay without draining the battery.  The ZXP or ZX alternator adapter plug that I Still make and sell to MSA for sale through them, CAN be used on the 73's once the instructions are more clear to the average "I don't do electrical" 73' 240Z owners.

     

    So please post pictures of the fuel pump relay(s) and the yellow wire.

    I and everyone else will greatly appreciate it.

     

    Dave

    Did you ever get the pics you needed? I can help

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