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Thread: 1973 240z electric fuel pump/alternator upgrade

  1. #1
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    Jan 2004
    San Francisco, CA

    Default 1973 240z electric fuel pump/alternator upgrade

    Hi all

    A few days ago I upgraded the alternator on my 240Z to a 60amp Bosch model from motorsports ( The kit somes with a cap for the wiring harness to replace where it connected to the voltage regulator that bolts onto the fender.

    A few interesting things came of this, and I am hoping to get some feedback from you folks.

    After the install, when I turned the ignition to the "on" setting, before starting the engine, I heard a rapid clicking sound coming from the right rear of the car which wasn't there before. I checked and it was the electric fuel pump making the noise.

    If I reinstall the older voltage regulator, the clicking goes away. I don't know if I can run this new alternator with the old regulator though, and would like feedback on that.

    I noticed that the adapter plug (that goes over the wiring harness when you eliminate the old voltage regulator) seems to have blown one of the links. it looks dark through the white plastic and the plastic near that looks marred. perhaps the adapter is faulty, or maybe it is intended for models that do not have the electric fuel pump?

    Part of what confuses me here is I thought that the 73 240Z only had a mechanical fuel pump, and that the electric fuel pump was added for the 260Z model. My production date is 6/73, so I wonder if they started doing that earlier. The electric fuel pump looks like a stock piece and looks like it is the original, as it is worn and rusted, and fuel seems to be leaking from the bottom. So one question is whether this is the stock setup for a June production 73 240Z, and whether I should replace the electric fuel pump or just eliminate it altogether. The fact that the wiring looks like it is original and pat of the harness and the pump looks stock leads me to believe it is the stock setup and should be replaced, but I am looking for confirmation.
    1973 Datsun 240Z

  2. #2
    Registered User Walter Moore's Avatar
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    Oct 2002


    The late 240Z had both a mechanical and an electrical fuel pump. There is actually factory wiring for the electric pump in all of the 240Zs I believe. I know that my 71 had wires in that location that go to an un-used connector.

    I don't know what the MSA setup entails, but I do know that the later alternators are internally regulated so using your original voltage regulator is not possible.

    I don't have any details that would explain why you only heard the "clicking" sound after the alternator upgrade. Check with MSA as they may have encountered this phenomenon before.

    I believe that the adapter they provided may have been made by someone here on this site. Perhaps they can chime in. (Sorry, I can't remember the name at the moment.)
    '71 240Z, Because any fool can drive fast in a straight line.

  3. #3
    Supporting Member =Enigma='s Avatar
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    Sep 2005
    Santa Cruz, CA


    My current understanding is that electric fuel pumps found on 1973 240Zs and 1974 260Zs were added as part of multi-option fix for vapor lock and percolation issues related to the Hitachi flat top carbs used on these cars. In other words, they did not come installed as stock equipment. This has been covered many times so I won't go into the details here but it's worth a search to learn more if you're interested. There's also a PDF of the modifications floating around here somewhere, but it can also be found on
    4/73 - HLS30-156236

    My name is Adam and I'm a Zeeoholic!

  4. #4
    Registered User mayitin's Avatar
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    Jun 2003


    These guys are right. my memory may fail me but I think those electric pumps have a filter inside them a little round one, looks like a minature airfilter. I have a 73 and I put on a different pump and I did change the Alternator, I bought mine from the people in Oregon and what a difference it made the 90 amp lights became bright and other things started to work. make sure you connected every thing right make sure you are well ground, these cars need a lot of ground.

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