Very low Velocity issues

[Prometheus]

So weird yesterday it wasn’t shooting at all after replacing everything. Today I hooked up my hpa 9ci tank worked great. Then switched to 12 grams worked great. This is the problem though. I think it’s fine and soon as I go to play actual match works for maybe 30-40 shots then all the sudden isn’t. Keeps giving me false hope maybe o should fire another 30-40 and see if it’s holding up.

[flyweightnate]

How much "rattle" is there between the power tube and nut? I'd wipe off any oil there, and make sure it is smooth with extra room in case the nut shrinks from the CO2 chilling it. I doubt it, but it's just a thought.

Try a Teflon washer for the cup seal, if you can find/ cut one the right size. Or get old urethane seats.

And, take photos of all the parts, and show us! I'm curious what might be different.

[Ordo]

Is your cup seal a softer material or a hard/thin white delrin(?)?

I’ve fiddled with quite a few phantoms from EV experiencing a similar problem. No noticeable leaks down the barrel like you’d expect from a blown cup seal, but would run well briefly and then crap out. Unable to get useable velocity from tanks or 12s. Roll out shots, etc.

the one thing I was able to isolate to solve the issue was there was a period of time that EV was shipping their power tubes with a cup seal that was a softer yellowish/clear rubber material. Unsure of the actual material type. They’ve now apparently switched backed to a thin delrin(?) cup seal a lot like their puncture pin seals.

swapped the softer material cup seals for the harder ones and it solved the problem. the cup seals they sell online are now of this harder type too.

[Prometheus]

Awesome I’ll look at it in a bit. I did order a new one one in the case that it might be. Sure hope that’s it should be a easy fix.

[Myrkul]

It's definitely the cupseal. A local at the field had one that was doing this, and an older one he sold me. He replaced the cupseal right before selling it to me, and mine started doing it too. Especially playing out in these hot summer months, the heat softens the cup seal material too much and it prevents the valve from opening.

I just slapped a Spyder cup seal on mine and haven't had a single issue since.

[Prometheus]

[Ordo]

Just as I suspected. That’s your culprit.

[Prometheus]

Feel like they don’t fit the same The hole is smaller on the newer one. Or is this the wrong seal?

[Prometheus]

So can’t get it seated all the way

[Prometheus]

Does it not slide all the way down?

[Prometheus]

Because the one that was in there slid down onto the brass fitting there. This one the hole isn’t big enough.

[Ordo]

Seat the seal it into the brass cup, then thread your power tube into it. It will slightly stretch the inner hole to accommodate. I PMed you some pictures of mine.

[Chuck E Ducky]

It’s 100% EV cup seals they must have used a different material. We fixed a bunch at Slims. I think they used a material that is permeable to CO2. Like a black bunna oring will swell under co2 pressure. I think there cup seals are doing the same. They work on HPA because it’s not penetrating the face seal. It also why after it sits for a bit it works. The face seals are sticking Causing erratic velocity.

We have a member that’s going to make some new ones out of high quality material. For now find an old Cup seal.

[Prometheus]

It fits in the cup just doesn’t seem to screw down all the way when I go to tighten it

[Chuck E Ducky]

Ok it’s the right seal then put the lil brass piece in the seal first. Lip side toward the power tube like you have it in the picture above. You may need to force it a lil bit. Then place it on the power tube lil light hold lock tite on the power tube threads.

[pdogg77]

Just saw this... My EV phantom started doing the same thing today. See thread. Only difference is it shipped with non-silver springs

[Prometheus]

Thanks everybody. Got it all back together. Going to test it out tomorrow. Don’t wana make the neighbors mad tonight.

[iamthelazerviking]

I'm actually experiencing this with an older Phantom/older guts, and it could just be cup seal and/or puncture pin seal. I have a new one of both from EV as of recent, so need to double check the material.

[Chuck E Ducky]

That actually makes sense if my theory is correct about the new cup seals. It’s actually a good thing since it’s an easy inexpensive fix for them.

[Stockclass Heroes]

A quick fix is to find a lapco/nylon 6-32 one piece cup seal. ASP has them


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[Chuck E Ducky]

How do they hold up?

[Have Blue]

[quickly adjusts stock on site, as I'm not sure how many are actually left, since I bought all that Lapco had, and they aren't making any more]

[Prometheus]

It’s alive! I believe at least this weekend will be the true test. Replaced the cup seals and I shot 50 rounds through it on the crappy crossman 12gs. Shot good! Will update you all Saturday night.

[Chuck E Ducky]

Get a hard line in it. That’s a beautiful marker love the color combination!

[Mr. Hick]

its early and I haven't had my coffee... if your air line, brake line?

[Prometheus]

Good ol macro line. I’ll prob do a silver hardline kit soon. The macro line does make it much easier to take apart. Granted I hope I don’t have to do that as much now.