| [GMCnet] jc4 pump weirdness [message #127846] |
Sat, 28 May 2011 20:26  |
KB
Messages: 1262
Registered: September 2009
Karma: 0
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I recently installed a JC4 vac pump to provide braking in case the
engine dies while driving. I confess, I haven't actually driven with it
yet. I tested my installation with the key on and the engine off and
the pump came on after its 5-second delay as expected, then shuts off.
The weird thing is it keeps cycling on briefly about every 15 seconds or so.
Is this normal, or an indication of a vacuum leak? I'd read that the boosters
do leak, so maybe that's it??
thanks,
Karen
1973 23'
1975 26'
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Karen
1975 26'
San Jose, CA
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| Re: [GMCnet] jc4 pump weirdness [message #127866 is a reply to message #127846] |
Sat, 28 May 2011 23:53  |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Is your foot on the pedal when the pump is running? If the answer is no, then you have a vacuum leak which is probably in the booster. If the booster is leaking get a new sensitized one from Jim K.
I believe Jim B also has them but from a different rebuilder. I'm not familiar with Jim B's sensitized boosters.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] jc4 pump weirdness [message #127877 is a reply to message #127866] |
Sun, 29 May 2011 09:23 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Ken,
I have one from Jim B in Double Trouble, it works very well and I am
COMPELETLY satisfied with it.
Regards,
Rob M.
USAussie - Downunder
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Ken Burton
Sent: Sunday, May 29, 2011 2:54 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] jc4 pump weirdness
Is your foot on the pedal when the pump is running? If the answer is no,
then you have a vacuum leak which is probably in the booster. If the
booster is leaking get a new sensitized one from Jim K.
I believe Jim B also has them but from a different rebuilder. I'm not
familiar with Jim B's sensitized boosters.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] jc4 pump weirdness [message #127894 is a reply to message #127846] |
Sun, 29 May 2011 13:08 |
KB
Messages: 1262
Registered: September 2009
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Thanks Ken. No, my foot wasn't on the pedal. I'll do more investigation.
thanks,
Karen
> Is your foot on the pedal when the pump is running? If the answer is no, then you have a vacuum leak which is probably in the booster. If the booster is leaking get a new sensitized one from Jim K.
>
> I believe Jim B also has them but from a different rebuilder. I'm not familiar with Jim B's sensitized boosters.
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Karen
1975 26'
San Jose, CA
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| Re: [GMCnet] jc4 pump weirdness [message #127901 is a reply to message #127894] |
Sun, 29 May 2011 14:28 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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| KB wrote on Sun, 29 May 2011 13:08 |
Thanks Ken. No, my foot wasn't on the pedal. I'll do more investigation.
thanks,
Karen
> Is your foot on the pedal when the pump is running? If the answer is no, then you have a vacuum leak which is probably in the booster. If the booster is leaking get a new sensitized one from Jim K.
>
> I believe Jim B also has them but from a different rebuilder. I'm not familiar with Jim B's sensitized boosters.
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You have a vacuum leak somewhere. My First guess is the booster. After that it could be the check valve or the connection hoses. Finally it could be the pump.
You might unplug the check valve from the booster after it has been sitting for a hour or so. If you hear a vacuum sucking sound when you unplug it, then the booster is not leaking. I have unplugged some in the junk yard that have been sitting for months and still have vacuum stored in the booster. If there is no sound then you have a bad booster or check valve.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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