 Testing a four MPS, one holds vacuum but it's erratic |
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| Mark Henry |
 Feb 18 2021, 01:56 PM
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#1
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that's what I do!  Group: Members Posts: 20,065 Joined: 27-December 02 From: Port Hope, Ontario Member No.: 26 Region Association: Canada  |
Hi All!
Ethan just tested four MPS on a '74 2.0 we have here and it seems one holds pressure but it runs erratic. We tested the three other MPS and they tested good. I know that even if an MPS tests good, old MPS's the diaphragm's often fail once pressed back into service. Would the Tangerine MPS diaphragm kit help this, or is there something else likely going on? |
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| JeffBowlsby |
Feb 18 2021, 03:11 PM
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#2
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914 Wiring Harnesses Group: Members Posts: 8,663 Joined: 7-January 03 From: San Ramon CA Member No.: 104 Region Association: None 
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QUOTE(Mark Henry @ Feb 18 2021, 11:56 AM)  Hi All! Ethan just tested four MPS on a '74 2.0 we have here and it seems one holds pressure but it runs erratic. We tested the three other MPS and they tested good. I know that even if an MPS tests good, old MPS's the diaphragm's often fail once pressed back into service. Would the Tangerine MPS diaphragm kit help this, or is there something else likely going on? Open it up and see. Bet the diaphragm is ruptured, or at least the case is not vacuum tight. Another issue may be corrosion on the coil shaft, or a distorted plate spring. When vacuum is pulled is it a smooth transition or is there any point where there is a pinging sound or sudden jerk of the increasing/decreasing vacuum signal? If so, that is not good and could be cause of the erratic behavior. That MPS could be unrepairable if this is what is happening. |
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Posts in this topic
Mark Henry Testing a four MPS Feb 18 2021, 01:56 PM
Mark Henry Thanks Jeff, I see Chris' kit also has a coupl... Feb 18 2021, 03:23 PM
DRPHIL914
Thanks Jeff, I see Chris' kit also has a coup... Feb 18 2021, 04:10 PM Mark Henry Thanks Feb 18 2021, 04:22 PM MikeM Mark...I have one that has failed electrically. Th... Feb 19 2021, 11:20 AM Mark Henry Thanks, yes I figured as much.
The one that's... Feb 20 2021, 12:45 PM mgphoto I’ve rebuilt about a half dozen using Racer Chri... Feb 20 2021, 01:46 PM 914_teener I had one that was partially cracked.
Would opera... Feb 20 2021, 10:44 PM warpig Had a similar prob. Rebuilt MPS and would run erra... Feb 21 2021, 12:20 PM r_towle Order kit (s)
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Then open MPs Feb 21 2021, 06:25 PM |
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