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Can fuel pump pressure close to 6 hurt Solex needle valves / seats

Discussion in 'Fuel System & Electrics' started by VaiseW, Aug 24, 2021.

  1. VaiseW

    VaiseW Active Member

    Messages:
    129
    Location:
    Burleigh Heads, QLD, 4220
    I have original solex carbs on my 1975 2L kombi.

    On my recent trip around Australia, along with other work, I had my fuel pump replaced with a Pierburg 3-5psi lift pump model 721.440.51. All work done by Andrew (1500king/volkesdoktor) in South Austtralia. In addition a fuel cut off solenoid was added for safety and all re-plumbed. Pressure was then measured at the carbs of just under 6psi. This was much better than the flipping to ZERO the old pump was doing, and the likely cause of the lean running etc.

    Now I am back at home, and my usual mechanic pointed out that the pressure may be too high for the needle valves and seats (whatever they are). I did some googling, and for example on justkampers, their fuel pumps have a note that reads 'a fuel pressure regulator is recommended with these pumps'. I read that 2.5-3psi is what is needed. Other VW parts websites are selling things like the Malpassi Adjustable pressure regulator for my car.

    So - do I need to worry ?
     
  2. Mordred

    Mordred Super Moderator Staff Member

    Messages:
    3,005
    Location:
    Penna, Hobart
    Would be better if you reduced it a little. A couple of PSI high is unlikely to make a significant difference but may overly strain the system in the long term. Do a bit of research on the regulators, there is quite a bit of work (and cost) goes in to designing a good one. Don't go for a cheap one, you get what you pay for with these.

    Bear in mind that Andrew uses the original quality needle and seats which have a much lower failure rate than a lot of cheap copies.

    Adrian
     
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  3. Barry

    Barry Well-Known Member

    Messages:
    5,911
    Location:
    Abbotsford NSW
    cbus and KahunaKombi like this.
  4. VaiseW

    VaiseW Active Member

    Messages:
    129
    Location:
    Burleigh Heads, QLD, 4220
    I did not get new needle and seat stuff with the carb work however. So no idea on their current operation.
    I imagine Andrew would have checked them and replaced them if need be however while he was fixing a leak.
    Work done I noted at the time was - removed idle jet o rings (not needed), changed main, idle and air correction jetting to 2L specs, fuel accelerator pump diaphragm replaced and milled flat, pin replaced and spring repaired. Also the choke units replaced and working. No mention of anything else regarding the carbs.
    I don't want to direct bother Andrew needlessly, I will be going there again once all the lock downs end, on the way to a WA trip - finish of the circumnavigate of Australia that we started. This time will head inland from Gold Coast, then down to SA.
     
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