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Pop off pressure tool help

Turd Furgeson

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Hey Guys,

I'm trying to revive this old dealership tool I picked up from ebay that was DOA. I know I can get a chicom, but I like saving merican things. I can't get it to build pressure. It will develop pressure if I cover to the two intake holes on the plunger before I depress it. I replaced the o-ring on the plunger which gives better sealing than the one that came out of it. I think it's missing a one way intake valve, but i can't find a diagram for the life of me. No response from Walbro support either. I'm guessing at one time a o-ring and stainless check ball or a duckbill valve resided in the plunger behind the spring. Would any brave soul be able to confirm this?


IMG_3621.jpg


Thanks,

TF
 
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srcarr52

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I took mine apart but it's a different design. You're correct in the fact that there needs to be a check valve in the plunger. Maybe you have it assembled incorrectly because the way its sitting now the aluminum plunger would be sealed against the brass washer all the time unless the line had more pressure than the pump. Which is opposite of how it's supposed to work.
 

Turd Furgeson

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I took mine apart but it's a different design. You're correct in the fact that there needs to be a check valve in the plunger. Maybe you have it assembled incorrectly because the way its sitting now the aluminum plunger would be sealed against the brass washer all the time unless the line had more pressure than the pump. Which is opposite of how it's supposed to work.
Thanks Shaun, I laid it out in the order it came apart. Granted it could have been put together wrong before I received it. The brass "washer" has a one way umbrella valve, so the orientation of the components in that end do make sense to me. Right now it's set to allow air passed the valve into the gauge area, but it shouldn't allow it to return to the plunger. I have some BB gun BB's and I put one inside the plunger in front of the spring last night. It will build pressure now, but it will not hold it. I think the umbrella valve has stiffened up enough that it won't seal properly. A soapy water check showed it wasn't leaking at the pressure gauge or the bleed off screw. I couldn't find an American source for a new umbrella valve of that size. It's about 12 mm. The closest I found was a 12.25 mm on AliExpress. The old valve has 251 on the end, I assume that was the size designation when it was made 40 years ago.

12-25mm-Small-Silicone-One-Way-Valve-Umbrella-Shape-For-Carburetor.jpg_Q90.jpg_.jpg


I'm not sure if the BB is the correct solution. It wants to draw a vacuum when the plunger releases. The existing umbrella valve leaks by when there is no vacuum on the back side as well. I pressurized it with another pump and it still bled off.
 

srcarr52

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I tore into my other tester and it's that same design. The spring has a duckbill valve inside it to seal the plunger.

IMG_4047.JPG
 

Turd Furgeson

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Cool! I figured it was missing something, there was goo in the spring, but not enough to account for dissolved duckbill. Now I just need to find the duckbill and umbrella valve. I have a few hundred duckbills that if memory serves me correct are close to that size. The umbrella valve will be the hard item to locate. I'll poke Walbro again, I have the feeling that's who supplied this gauge.

Thank you for the help! I owe you a beer.
 
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