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Fuel Pump check valve 700

posted by  someone claiming to be Art on  Thu May 15 05:11 CST 2008 [RELATED]

Where is the fuel pump check valve located ? (740 Regina, 1992, non turbo)








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    Fuel Pump check valve 700 1992

    uid 18083's pic
    posted by  lucid on  Thu May 15 05:35 CST 2008
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    last visit: Fri Oct 24 12:31 CST 2014
    [RELATED]

    The Regina FI system has no check valve. A good pump will raise line pressure from 0 to 43 psi in about 2 engine revs. That's what I measured on my 940 after a preemptive pump replacement.

    Contrary to a lot of conventional wisdom, the sole purpose of the Bosch check valve (at the pump) is to aid hot starts—rather than to hold pressure overnight.

    The theory is that by maintaining some pressure for a short time (the check valve spec is measured in minutes), it will prevent the vapor lock that might result from fuel boiling in the injector rail, due to heat soak from the hot engine.
    --
    Bruce Young
    '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.








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      Fuel Pump check valve 700 1992

      posted by  Chris Mullet on  Thu May 15 08:37 CST 2008
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      last visit: Fri Oct 24 09:08 CST 2014
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      "...it will prevent the vapor lock that might result from fuel boiling in the injector rail, due to heat soak from the hot engine..."


      Is that not one of the benefits of the "loop" fuel system (return line to tank) in that it pushes the vapor pockets out of the top of the rail and back to the tank?








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        Fuel Pump check valve 700 1992

        uid 18083's pic
        posted by  lucid on  Thu May 15 09:21 CST 2008
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        last visit: Fri Oct 24 12:31 CST 2014
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        "Is that not one of the benefits of the "loop" fuel system (return line to tank) in that it pushes the vapor pockets out of the top of the rail and back to the tank?"

        I couldn't argue against that, Chris. But most of the Bosch FI applications still seem to use a check valve (see Bentley 230-5). Maybe the Regina developers saw the logic of what you say.
        --
        Bruce Young
        '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.








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      Fuel Pump check valve 700 1992

      posted by  someone claiming to be joe on  Thu May 15 05:40 CST 2008 [RELATED]

      Mine is Regina, theres no valve at the pump but theres a threaded slug in the end of the fuel filter under the driver seat, thats a check valve. Its a bugger to remove, I just replaced the filter and brass valve together rather than fight with it, cost $6 from FCP.








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        Fuel Pump check valve 700 1992

        posted by  someone claiming to be Art on  Thu May 15 05:51 CST 2008 [RELATED]

        Joe, I was asking, b/c I just replaced the fuel filter. The brass adapter inlet the filter was straight through. I thought it might have been a check valve at first, but it just seems to adapt from one thread to another.








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          Fuel Pump check valve 700 1992

          uid 18083's pic
          posted by  lucid on  Thu May 15 07:44 CST 2008
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          last visit: Fri Oct 24 12:31 CST 2014
          [RELATED]

          I also replaced my 940 Regina filter and saw no check valve, nor is one mentioned in the Regina manual.

          My Regina "Green Book" makes no mention of a check valve for out-of-spec Residual Pressure. If pressure drops too fast (by gauge/time measurement), it suggests leaking fuel injectors or Cold Start injector (not present on some years). If injectors are OK, it says to replace Fuel Pressure Regulator. That's all.
          --
          Bruce Young
          '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.








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            Fuel Pump check valve 700 1992

            posted by  someone claiming to be Art on  Thu May 15 08:22 CST 2008 [RELATED]

            Green Book - where can I get one ? Sounds very useful!








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              Fuel Pump check valve 700 1992

              uid 18083's pic
              posted by  lucid on  Thu May 15 09:09 CST 2008
              Author: [PROFILE] [EVERY POST] [THREADS] [BEST POSTS] RSS Feed     [IGNORE ALL POSTS]
              last visit: Fri Oct 24 12:31 CST 2014
              [RELATED]

              Green Book or Greenbook is jargon for the factory service manuals. They are divided into many categories, and not cheap.

              You can get an idea by going to Volvo's online book store at https://www.volvotechinfo.com/index.cfm

              I called 800-25V-OLVO (258-6586) and had them mail me a complete hard copy listing of "Service Information" for the 1993 - Model 940, from which I ordered about $130 worth of manuals.

              For example, the manual I cited in this thread, "Fuel System Regina - Ignition System Rex-!, TP 31903/1" (150+ pages, including FI and Ignition wiring diagrams) is $29.15USD.
              --
              Bruce Young
              '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.







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