Coleman 502 has no pressure

Discussion in 'Fettling Forum' started by Terry Moore, Jun 13, 2019.

  1. Terry Moore United States

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    I bought a Coleman 502 recently that won't hold pressure. I have switched fill caps with a proven stove =no pressure
    I put a new seal in the old cap= no pressure
    If it makes any sense it feels like the pump is actually working but even though the stove is turned off completely it won't build any pressure. It was sold as a good working stove and looks very good but won't pressure up. Before I did a complete tear down I thought I should ask the experts if I'm needing to check something simple. HELP PLEASE
     
  2. Murph

    Murph United States Subscriber

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    Dumb question, @Terry Moore , but have you turned the pump handle anti-clockwise a turn or three to open the needle valve and let compressed air into the tank?

    With a good cap seal, well oiled leather pump leather, and the check valve isn't stuck, it should fire up with no problems!

    The 502 has to be one of the most bulletproof stoves made, they never have problems - almost!

    Murph
     
  3. Terry Moore United States

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    Yes I did that it don't make a leaking sound like escaping air and the pump SEEMS to be working but the stove just don't hold pressure at all even for a min ?
     
  4. snwcmpr

    snwcmpr Subscriber

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    So, when pumping, does it seem to be building pressure? Does it get harder to pump?

    Oh, does the pump push back on your thumb, with your thumb on the hole, after pumping?
     
  5. Terry Moore United States

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    After fiddling with it it seems the screw where the red knob screws in is leaking pretty bad and the knob turns freely to the left but will seat when turned to the right I don't have a diagram of what it is supposed to look like so I don't know if anything is missing in there or not but all that comes out is a shafts that screw in and appears to seat against something
     
  6. Terry Moore United States

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    After looking there seems to be a seal missing that is allowing the fuel to seep by. If I can't buy just the seal I'll probably need a complete valve assembly. Where would be the best way to find one
     
  7. snwcmpr

    snwcmpr Subscriber

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    Because of terminology it is a good idea to post photos, if you can.
     
  8. cottage hill bill

    cottage hill bill Subscriber

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    Sounds like he means the fuel valve is leaking at the gland nut.
    The big red knob is the on/off valve for the fuel. If it is open when you're pumping you won't get any pressure, it all goes out the generator.
    Turn the knob clockwise until it stops. Turn the pump knob 2 turns counter-clockwise, put your thumb over the hole in the knob and pump. The pump should get gradually a bit harder to pump after about 35-40 pumps. Push the pump in and turn clockwise until it stops.
    Now turn the big red knob a turn counter-clockwise and listen for air coming from the generator.

    Another way to test is to close the fuel knob, remove the fuel cap, put your thumb over the fuel-fill hole and pump 5-10 strokes with the pump. Remove your thumb from the fuel fill and you should hear a mild pop and feel the escaping air on your thumb.

    With the fuel knob opened 2-3 turns, tighten the gland nut (the 9/16" nut inboard from the fuel knob) until the fuel knob is hard to turn. Back the nut off one flat and see if the leak is fixed. You can tighten the gland nut until the fuel knob cannot be turned, then back it off until you can to compress the graphite packing on the valve. The valve should turn with some resistance, not hard, but not really loose either.

    If tightening doesn't fix the leak new packing is available from Old Coleman Parts. Look at the link below for a parts diagram for your stove.

    http://www.oldcolemanparts.com/diagrams/502-700.jpg