Fuel pump runs and does not run...

  • So I would say now that the car had an HVZ ex works and they thought of something. And even if it runs like this, I would say that it would run better with the HVZ. My opinion!

    :wink:

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    Porsche 911 SC / 930.10 Motor / Bj.1982 Pazifikblaumet.

    Edited once, last by Thorsten 911 (February 26, 2024 at 4:48 PM).

  • So I would say now that the car had an HVZ ex works and they thought of something. And even if it runs like this, I would say that it would run better with the HVZ. My opinion!

    :wink:

    ok ...I would like to believe....if the HKZ works properly etc. it will certainly be like that....

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    Porsche 911 Targa Saharabeige G 2.7 November 73

    schöne Grüße

    Roman

  • This is some kind of ignition box, probably even an HKZ, but not an original Bosch box. The early G still had breaker contacts in the distributor, so the conversion to a different ignition box was less of a problem with these (up to the end of MY1977, afaik). But that shouldn't stop us, because that's not the problem! The problem is the fuel pump that occasionally refuses to work. And it doesn't matter whether it's at the front under the tank or at the rear left near the rear wheel.

    What I would do (and what a technically inexperienced mechanic/screwdriver owner can be expected to do):

    Run two cables in parallel from the BP to the interior and connect a small light bulb in parallel to the BP - sort of as a live voltage check while riding. Careful wiring and caution against short circuits etc. are urgently recommended! Observe accident regulations!

    Pack a can of cold spray before the test drive and then drive. Observe when the lamp lights up and when it no longer lights up. Also pack a multimeter for troubleshooting on site, a few tools won't hurt either. And also a contact spray, no matter which one at first.

    Then - if the fault occurs - does the bulb light up or not?

    If yes - treat the BP with cold spray, does the BP run again afterwards? => Is the BP the problem (thermal cause, rust, etc.?).

    If no (i.e. the bulb is not burning) => electrical problem. If it really doesn't have a BP relay - unless there is a fuse in between - the only possible source of error for me is the ignition starter switch! Possibly a thermal problem here too => cold spray. In this context, you could also carefully heat the ignition starter switch with a hot air gun to provoke the fault in the garage, if necessary, without driving. I wouldn't do this with the BP (fire hazard...)

    In my opinion, the ignition starter switch is actually the most likely cause. This is because the contact can heat up so much during the journey due to the current that it still just about holds the contact during the journey, but the starting current of the BP is already too high when restarting (engine warm) that the contact resistance or the contact gap becomes too high and the pump then no longer starts. This would also be the solution in the event of a breakdown on the open road: Connect the BP with flying leads (with 10 or 15A fuse holder!!) directly to the battery. Use a cable cross-section of at least 1.5mm²!!!

    And please don't wrap the bare wire around the contacts, we want to use at least the 6.3mm automotive DIY cable crimp connectors or proper cable lugs on the BP...

    Greetings, Thomas

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    81er ex-US 911 SC Coupé, platinmet., eSSD, K-Leder sw., Turboheckflügel & -frontspoiler, NSW, Maxilite 7/8J, Bilstein Fw("SpoStra" - noch...), 915/61, 930/16 o.Kat, WebCam 20/21 NW, hydr.KS, Dansk 92.502SD, 123 Ignition, orig. Porsche SWV, Seine Systems Gate Shift Kit, Momo Prototipo m.Nabenerhöhung


    „Nicht das Auto verdirbt den Charakter, aber wer keinen Charakter hat, sollte nicht Auto fahren.“

    Ferdinand Porsche

  • I found this somewhere else

    wouldn't that also be possible for me?

    So, I'm going to resolve this. In case someone else has such a problem:

    The reason for the fuel pump getting hot was the fuel pressure regulator. Mechanic has identified it. Runs like clockwork again

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    Porsche 911 Targa Saharabeige G 2.7 November 73

    schöne Grüße

    Roman

  • Roman, a word of advice between you and me: if you would look for the error systematically instead of speculating and googling, the problem would probably have been solved long ago.... I've just written you my mustard in "novel form", take it, do it like this, or leave it. I don't care. I'm out of here now. Good luck.

    Thomas

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    81er ex-US 911 SC Coupé, platinmet., eSSD, K-Leder sw., Turboheckflügel & -frontspoiler, NSW, Maxilite 7/8J, Bilstein Fw("SpoStra" - noch...), 915/61, 930/16 o.Kat, WebCam 20/21 NW, hydr.KS, Dansk 92.502SD, 123 Ignition, orig. Porsche SWV, Seine Systems Gate Shift Kit, Momo Prototipo m.Nabenerhöhung


    „Nicht das Auto verdirbt den Charakter, aber wer keinen Charakter hat, sollte nicht Auto fahren.“

    Ferdinand Porsche

  • Thomas that sounds very constructive and good to me as a layman ...like you I also suspect the ignition lock although the BP is really buzzing like a mouse that is about to die..... although BP is new....thanks

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    Porsche 911 Targa Saharabeige G 2.7 November 73

    schöne Grüße

    Roman

  • Roman, a word of advice between you and me: If you would look for the error systematically instead of speculating and googling, the problem would probably have been solved long ago.... I've just written you my mustard in novel form, take it, do it or leave it. I don't care. I'm out of here now. Good luck.

    Thomas

    yes, I want to tackle it properly tomorrow.....thanks for the help

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    Porsche 911 Targa Saharabeige G 2.7 November 73

    schöne Grüße

    Roman

  • Quite a mess here. First HKZ no, then yes but expanded. then now BP new......... What now

    Klugscheissermodus to Thomas still from me HKZ Bosch part.... If it was an American then it wasn't Bosch but Permatune :P

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  • Quite a mess here. First HKZ no, then yes but expanded. then now BP new......... What now

    Klugscheissermodus to Thomas still from me HKZ Bosch part.... If it was an American then it wasn't Bosch but Permatune :P

    HKZ was not the topic BP last year new was clear...the contributions are not purposeful...Thomas has said everything......

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    Porsche 911 Targa Saharabeige G 2.7 November 73

    schöne Grüße

    Roman

  • Then I'll just leave it and wish you good luck, not that I'll end up being to blame if your car crashes. Sorry, but I've never had a response like this before.

    Over and out

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