1987 Coleman 425F, pump won't compress

Discussion in 'Stove Forum' started by PDKPDK, Aug 23, 2021.

  1. PDKPDK United States

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    Hi Everyone, newbie here to old Coleman stoves. Just picked up a 425F stove for free from a neighbor. In decent shape, but when go to test the pump, it won't compress much at all when my thumb is over the hole. It's like if you go to pump up the tires on your bike but don't have the valve seated correctly and there's no where for the air to go.

    Looking for all suggestions on how to diagnose and fix this problem so I can get the stove operational.

    Thank you all!
    PDK
     
  2. hikerduane

    hikerduane Subscriber

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    C/V may be plugged up or gummed up and not allowing the bearing in there to move. Also, will the pump shaft go down w/o your thumb over the hole? If the C/V is plugged, squirt some carb cleaner or acetone in the pump tube and let set 5 or 10 minutes. Hopefully those are the issue. Are you unscrewing the pump shaft a turn or two before pumping?
    Duane
     
  3. PDKPDK United States

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    Hi Duane, thanks for your quick reply. Yes, the pump shaft goes in/out freely when my thumb is not over the hole, and I'm unscrewing the pump shaft 1-3 turns before pumping. I will try the acetone. When you suggest squirting in the pump tube, are you suggesting I let it run down the sides of the shaft, or something else? Appreciate the help!
     
  4. Majicwrench

    Majicwrench Subscriber

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    So with pump unscrewed like you are doing and thumb over hole, can you not push it down, or when you push it down it doesn't feel like it is adding pressure??
     
  5. itchy

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    A common problem when stoves or lanterns sit unused for a long time.

    You should remove the pump shaft/cup assembly and the brass rod it slides on by unscrewing it several additional turns. This would be a good idea before putting solvents in the pump tube because you do not want to damage the pump cup if it can be avoided.
     
  6. cottage hill bill

    cottage hill bill Subscriber

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    Easiest is to remove the little wire clip holding the pump cap on. Then take take the pump cap off. You may need to pry gently with a screwdriver blade or similar if it's stuck to the tank. Pull the pump rod out, then unscrew the air stem (the square rod) and take it out. It helps to unscrew the air stem a few turns before you pull the pump rod. Look down the pump tube and you'll see the check valve (CV). It's a brass piece with a slot like a screw and a hole in the middle. Pour in enough solvent to cover the CV. Prop the tank so the pump tube is vertical and let it sit for a while. Leaving the air stem out for now, put the pump rod back in place and try to force the solvent through the CV. If you have trouble keeping the pump leather centered you can add the air stem as a guide, just leave it unscrewed about half way. You can use something like a bamboo skewer to poke into the hole in the CV and try to move the ball. The CV has a steel ball trapped inside. Air pressure from the pump pushes the ball down and air flows into the tank. When the pump is still, air pressure from the tank pushes the ball up against a seat preventing air from coming out. The CV is not an airtight seal, the air stem being screwed in is the air tight seal. When old fuel dries and hardens on the ball it gets stuck and can't do its job. WD40 is a good solvent for grease and fuel. You might try a bit of that followed by acetone. Acetone is also good. Either way let the solvent sit for a few hours.
     
  7. PDKPDK United States

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    Thanks everyone, I removed the pump shaft/assembly and it appears in good shape. I will add some solvent in the tank and let the check valve sit in it for a few hours as suggested. Will report my progress, thanks again.
     
  8. BradB

    BradB United States Subscriber

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    I think the most common cause of your symptoms is a dried pump cup. First I would squirt some oil into the little hole. If that doesn’t fix it, remove the pump as described above. If it is a rubber looking ring, oil it and reinstall. If it is leather, soak it in oil for an hour. Anything from 3 in 1 to clean engine oil to neatsfoot will work. Sometimes the leather ones need to be reshaped by bending the leather back to increase the diameter. If either the neoprene type or leather need to be replaced, try here at the Fettlebox on CCS or Old Coleman Parts. Since the stove is 1987 it will likely be neoprene. Brad
     
  9. Dean

    Dean United Kingdom Subscriber

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    @PDKPDK Not had experience with Coleman stoves but have had similar issues with Swedish or British brassies. You pump and it goes hard as there is nowhere for the pressure to go to. In my case the Non return valve has been stuck shut and needed a little persuasion.
    A squirt of penetrating oil, Plus gas or similar, leave it to soak then try pumping again; the other way was to push the pump in until you get resistance, then, without releasing the pressure, smack it one! I realise that may not be possible with the Coleman, due to needing to keep the little hole covered but it can work with the brassies..
     
  10. presscall

    presscall United Kingdom SotM Winner SotY Winner Subscriber

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    Purists, avert your gaze.
     
  11. BradB

    BradB United States Subscriber

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    I misunderstood your symptoms, as I thought you meant the pump went too easily but caused no pressure. If that is the case, service the pump. If it seems too hard, then yes, the check valve.
     
  12. PDKPDK United States

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    Hi All - problem solved, check valve was stuck. Took everyone's advice and let it sit for 3 hours this afternoon with penetrating oil, pump now works and seems to hold pressure nicely. Now, need to get some fuel to test light it.

    Thank you to everyone who shared their expertise!

    Pat