77 GTB Fuel Problem | FerrariChat

77 GTB Fuel Problem

Discussion in '308/328' started by 77GTB, Sep 14, 2017.

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  1. 77GTB

    77GTB Rookie

    Oct 14, 2014
    14
    East Bay, CA
    Full Name:
    Chris
    I have a 77 GTB (carb w/ electronic ignition) that is having a fuel problem. I just completed replacement of the filler hose and tank crossover connections. Prior to starting that, I completely drained the gas through the drain plug in the crossover. Afterwards I put 5 gallons in and tried to start the car. Turned the key, to let fuel pump run for at least 30 seconds then tried cranking. Car would just crank and crank but never attempt to start running. Tried that several times.

    Typically after cranking that long and that many attempts, you would definitely smell gas and it would likely be flooded. However, there was no smell. I then pulled the fuel hose off the carb and turned key to run the pump, no gas.

    I've since put another 5 gallons in hoping the extra would help gas into the system, no such luck. Still no gas getting to carbs.

    The car started and ran fine prior to fuel line work and nothing else was changed. The pump is still making the same noises it always has. Is there something that needs to be done after draining tanks to get get fuel flowing?
     
  2. mlflotus

    mlflotus Rookie

    Jan 24, 2004
    31
    60015
     
  3. mlflotus

    mlflotus Rookie

    Jan 24, 2004
    31
    60015
    When you drained the gas you probably loosened a lot of crud. Check your fuel filter. You could also loosen the fuel line from the fuel pump to check the pump's output.
     
  4. Tortellini

    Tortellini Rookie

    Sep 27, 2014
    47
    S.E. Michigan
    +1 ....Just drained fuel & rebuilt carb tops on my '77 (was flooding, think due to old gas clogging float valves)... will try to re-start soon.
    Let us know how you get on...
     
  5. Martin308GTB

    Martin308GTB F1 Rookie

    Jan 22, 2003
    4,212
    Black Forest Germany
    Full Name:
    Martin N.
    Yes. Let us know how you get on. I plan to tackle this job during coming winter.

    Best
    Martin
     
  6. 77GTB

    77GTB Rookie

    Oct 14, 2014
    14
    East Bay, CA
    Full Name:
    Chris
    Problem solved!

    I was sure it was going to be the filter as suggested above. However, after checking flow through the filter (I do have a new filter on order anyway) it was not the problem. Then I went directly to the pump which was also working just fine. My car has a unidirectional valve plumbed between the filter and pump. You can see the valve and discussion in this thread:
    http://www.ferrarichat.com/forum/threads/308-unidirectional-fuel-valve-111790-is-it-needed.124300/

    My valve had become completely clogged and was not allowing fuel through. I removed the valve from the system and plumbed it per Euro spec, from tank to filter to pump to carbs. Car started right up!

    I figure that the valve must have been partially blocked for a long time. After removing, the car starts much easier and no longer bogs when flooring it after sustained low rpm cruising.
     
  7. Tortellini

    Tortellini Rookie

    Sep 27, 2014
    47
    S.E. Michigan
    Great to hear! ...and good to know.
     

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