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fuel oil dripping fuel out of nozzle

Help, I have a fuel oil burner that is leaking fuel oil out of the nozzle after the burner shuts off. This causes a carbon ball that shuts the unit down. The burner papers say to set the fuel pressure at 90#. The unit burns and lights fine untill this builds up. The fuel tank is in the basement with the unit, so I have ruled out air pockets in the line. It is 1 pipe system. Is there a low pressure ajustment on the pump to stop this? A new nozzle did not correct the problem. What am I missing? Thanks for any help you can give me.


  • Marty handyman
    Marty handyman Member Posts: 4
    Leaking nozzle

    Do you have afterburn? I had similar experience recently with Becket burner on my Blueray III [Thermodynamics] boiler. It was starving for air because I had plugged up an outside wall vent to keep out the cold! [dumb]. It took 3 months from last cleaning to soot up again. Heat builds up from lack of air movement inside, nozzle overheats & draws fuel out of the line. I opened the vent & it's been fine since.
  • Anthony D.
    Anthony D. Member Posts: 63

    It is usually caused when you have excess heat in the fire box after the burner shuts down. It happened to me recently on a furnace with a draft inducer. I had to increase the post purge timing to draw off the heat. If you have natural draft, check the draft on the off cycle. Also you might want to check the fan limit setting if its a furnace.

    Good Luck
  • J.C.A.
    J.C.A. Member Posts: 349

    #1 Fuel oil nozzles are rated at 100 PSI. #2 need way more information to help . Is it a boiler or furnace ? What brand of heater AND burner ?Burner motor speed ? How old is this unit ? How long of a run does the fuel make and is the tank above the burner ? What size is the oil line ? Most importantly , do you have the instructions that came with the unit ?

    The more I have,the better to help you with. Chris
  • Pat
    Pat Member Posts: 25
    oil drip

    They make a check valve that can be inserted in the nozzle adapter before the nozzle is screwed in. Marginal success. But 1st check pump - will it hold a vacuum. Make sure oil isn't leaking by the seat. Usually the heat of the fire box draws the fuel out of the gun line will burner is off. As suggested a longer post purge will improve the situation.
    Good Luck.
  • Wayco Wayne
    Wayco Wayne Member Posts: 615
    I don't work on oil

    but I just happened to read the other night that a fix for oil dripping after the cycle could be fixxed by installing a solenoid in the oil line and wiring it in parallel to the heating circuit. I'm sure there's better informed sources than me on this though.

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  • HBW
    HBW Member Posts: 33

    Air trapped in the nozzle line could be the cause, some nozzle lines have a steel rod inside them to reduce the volume of oil which helps reduce this drip, manualy fill the line with fuel oil. Also you might want to get an oil pump test gauge. This will tell you if the pressure regulator in the fuel pump is cutting out sharply or leaking by. If all else fails, a nozzle line solonoid might help.
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