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Author Topic: Crosman 1377 Losing power  (Read 162 times))

Offline Alanheal

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Crosman 1377 Losing power
« on: February 23, 2021, 12:56:00 PM »
Greetings,

My Crosman 1377 is losing power.   It became too easy to pump. I've had it about a year, and used it often.  What is the likely problem and where do I get the parts?

Thank you
  • Pennsylvania

Offline Alanheal

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Re: Crosman 1377 Losing power
« Reply #1 on: February 23, 2021, 05:09:05 PM »
Greetings,

My Crosman 1377 is losing power.   It became too easy to pump. I've had it about a year, and used it often.  What is the likely problem and where do I get the parts? What's odd is that if it sits for a few hours or a day, it will start working again, and then on another day it will lack power again. ??

Thank you
  • Pennsylvania

Offline CENTURION

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Re: Crosman 1377 Losing power
« Reply #2 on: February 23, 2021, 05:32:19 PM »
I would first try adding pellgunoil or ATF, parts for the re-seal can be ordered through Crosman.

Online Spooner

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Re: Crosman 1377 Losing power
« Reply #3 on: February 24, 2021, 04:14:17 AM »
If it's pumping without or with reduced resistance it is most likely the pump cup. It could also be the transfer port seal, or a valve seal but based on what you are describing... im betting the pump cup. Did you try the tissue test? Lay a piece of tissue over the side of the breach with it unloaded and pumped a few times and cocked... then pull the trigger. If the tissue moves... it would tell you if there is a leak in the transfer port seal area.  ;)
  • Ohio

Offline DRose

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Re: Crosman 1377 Losing power
« Reply #4 on: February 28, 2021, 08:05:02 PM »
First check you pump linkage. Slop and wear in the linkage will not allow full pressure to build for each pump.
  Those pump cups are something else. You can never tell by looking if it is good or bad.
It may be time to reseal the whole pistol. Easy to do and parts readily available from Crosman or Ebay.
I would get a new valve complete and several pump cups just to have on hand. Good luck! Dave
  • Crown City, Ohio

Offline Alanheal

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Re: Crosman 1377 Losing power
« Reply #5 on: February 28, 2021, 09:32:40 PM »
Thank you for all the suggestions.  I subsequently bought the parts and attempted to change the pump cup and valve.
  • Pennsylvania