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308 Carb 3 way fuel valve

Discussion in '308/328' started by DonB, Mar 19, 2021.

  1. DonB

    DonB Formula Junior
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    Nov 11, 2003
    616
    Florida
    Full Name:
    Don Bartz
    OK....

    This was covered previously on FChat but thought I'd bring it to the forefront again. Perhaps it might help someone.

    So forever it seems my '79 U.S. 308 didn't run quite right. The carbs had been rebuilt, and the ignition was/is perfect. All stock with exception of CAT by-pass pipes and no air pump and associated parts (all in a box on the shelf).

    However, the car has been a bit difficult to start after sitting for a spell and when starting out driving, it would "spit" through the carbs (I installed Weber individual air cleaner assemblies and everything through the carbs can be heard). If I shifted to a higher gear the spitting would stop.

    After warming up it ran OK but still it would occasionally "spit" while cruising and when accelerating it would stumble going from low circuit to high on the carbs.

    Well the other day a fuel drip near the filter assembly revealed a leaking 3 way valve (PN 111790) that is present on U.S. cars but not Euro cars. This was confirmed by FChat and by checking the parts diagrams for the two models. Well these valves are NLA of course so out came the JB Weld. After fixing the leak, but prior to reinstalling it, I decided to check flow through the valve. What flow? There was virtually none. The system, having previously been checked, had pressure but apparently the flow volume wasn't checked.

    So, once again relying on FChat info, I completely eliminated the valve and ran a straight line from the pump (a Facet unit) to the carbs. Whoa Nelly! Does it run now! Ladies and Gentlemen it's like a new car. No spitting, no stumbling, just pure fun. And the induction noise coming from those 4 carbs is heaven, especially near red line! It's just simply amazing how well carbs work when they actually get the correct amount of fuel! Who knew? :)

    FYI, for the new fuel line I used Weatherhead cloth wrapped 5/16" fuel line from NAPA. It's very expensive but very high quality.
     
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  3. ferrarioldman

    ferrarioldman Formula 3
    Silver Subscribed Professional Ferrari Technician

    Jun 19, 2002
    1,026
    Summerfield, NC
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    Tom Jones
    Recently had the same issue and did the same thing. Checked fuel pressure and was in spec. Ran great.
     
  4. AZDoug

    AZDoug Formula 3

    Jun 17, 2009
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    Doug
    What was the purpose of this valve that is not needed?

    Doug
     
  5. Kidasters

    Kidasters Formula Junior
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    Oct 4, 2013
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    Houston, Tx
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    Ken
    I'd like to see a picture of this. I don't remember this part on my car.
     
  6. Kidasters

    Kidasters Formula Junior
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    Oct 4, 2013
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    Ken
    OK - I see now.

    It's a 70's emissions part. I had one on my old BMW 2002 as well - and a guy recommended I yank it off and throw it in the neighbor's pool.

    Mine is missing - I'm plumbed directly from the fuel pump to the carbs. I know, because I ran the line from the carbs directly to the pump.

    Changing the fuel line is an excellent idea. I bought some Viton hose from Jegs for all my under hood fuel lines. It's resistant to the Ethanol, and I know it's fine with volatile hydrocarbons up to 400 F, because we tested that at work.
     
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  8. lm2504me

    lm2504me Formula Junior
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    Aug 26, 2004
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    Richard
    Not emissions. Safety feature. If fuel hose down stream of this device is ruptured, the low / zero pressure causes the valve to shut off the fuel to the suction side of pump.
     
  9. 4right

    4right F1 Rookie
    Rossa Subscribed

    It sounds like a check valve that prevents fuel from flowing backwards. I also removed this from my 79 308 years ago when it started leaking.
     
  10. MFlanagan

    MFlanagan Karting

    Dec 21, 2016
    112
    Is there a suitable replacement valve?
     
  11. Kidasters

    Kidasters Formula Junior
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    Oct 4, 2013
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    Ken
    Yes - nothing.
     
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  13. DonB

    DonB Formula Junior
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    Nov 11, 2003
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    Don Bartz
    Interesting how the Europeans of the era didn't worry too much about certain things!
     
  14. DonB

    DonB Formula Junior
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    Nov 11, 2003
    616
    Florida
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    Don Bartz
    We're fortunate here in Florida since we can get non ethanol 89 Octane gas at the pump..for rec purposes of course ;-) We're also able to get 100 Octane leaded aviation fuel that's available for the Air Boat guys (about $4/gal). That works really well in my car, and the smell is good too not to mention the nice white/gray tail pipes!
     
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  15. AZDoug

    AZDoug Formula 3

    Jun 17, 2009
    1,505
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    Doug
    With the crappy fuel line the cars came with, I see why they had the valve.

    Modern SAE J30, R9 fuel injection hose, cures the crappy fuel line problem, it is high pressure rated and immune to ethanol gas.

    Doug
     
  16. lm2504me

    lm2504me Formula Junior
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    Aug 26, 2004
    902
    Nipomo, CA
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    Richard
    It is used to stop fuel from fuel pump in case of an accident which causes the fuel line from pump to carbs to be severed. In an accident, the fuel pump would continue to run and feed fuel to the fire.
     
  17. AZDoug

    AZDoug Formula 3

    Jun 17, 2009
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    Doug
  18. DonB

    DonB Formula Junior
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    Nov 11, 2003
    616
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    Full Name:
    Don Bartz
    Actually not a bad idea. Perhaps mount it in line on the negative cable that goes from the pump to the chassis? However it's too cheap. If it's going on a Ferrari it needs to cost at least $200 maybe..or more?
     

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