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Fuel Delivery Problems 1986 W-150 5.9L

Discussion in 'Pre-1994 trucks, commercial vehicles' started by C. Cantrell, Dec 28, 2017.

  1. C. Cantrell

    C. Cantrell New Member

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    Greetings.
    My carb doesn't always hold fuel when not running. If it sits for 30 minutes or so it will or will not start without priming it. Once it starts it runs good. I am thinking the fuel return line is draining the carb sometimes and sometimes it doesn't. Thought about just plugging the return line. Any ideas?
    Thanks!
     
  2. Best Answer:
    Post #2 by ImperialCrown, Dec 29, 2017
  3. ImperialCrown

    Level III Supporter

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    Fuel drain-back from defective fuel pump check valves is common on an old pump. Fuel should flow one-way and not the other. You want the return line as an excessive pressure 'vent' back to the tank.
    Sinking carb floats and porous gaskets can cause leak-down, rich mixtures/vacuum leaks and flooding.
     
    C. Cantrell and valiant67 like this.
  4. C. Cantrell

    C. Cantrell New Member

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    It has a new fuel pump, could be defective but I'm going to get a carb kit and try that.
    THANKS!
     
  5. dana44

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    Yeah, you don't want to remove or plug the return line, the carb would more than likely flood all the time, it's there for a reason. Besides, the return line is high enough that it should not be capable of draining the carb. Might want to get a new float. When you remove the carb top, notice the amount of fuel in the bowl. I would start the engine to fill the carb and run a couple minutes to fill the carb, then pull the top off before removing from the engine (and not run so long that you can't touch anything), and observe if the fuel level drops over the next 20 minutes or so, may be a crack internally that is causing the issue.
     
  6. C. Cantrell

    C. Cantrell New Member

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    Good advice, Thanks!
     
  7. C. Cantrell

    C. Cantrell New Member

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    Good advice, THANKS!
     

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