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| JC4 Vacuum pump operation and additional wires [message #326643] |
Sat, 02 December 2017 11:53  |
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RF_Burns
Messages: 2276
Registered: June 2008
Location: S. Ontario, Canada
Karma: 3
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So I had the key on ACC last night pumping up the rear suspension to put blocks under the rear bogies for the winter. I noticed my JC4 brake vacuum pump was cycling, and driving my Digipanel low voltage nuts, so I thought I'd check the voltage going to it.
I followed the main power(I thought) to the battery 12V terminal and measured the voltage. There was very little change there, so I pulled the fuse... the pump continued to cycle. So I wondered if I got the Ignition and 12V wires reversed. I was under the assumption from wiring diagrams on the Net that +12V was the main power wire from the Motor, and Ign was just a sense wire. But turns out the motor power is taken from the Ignition line, hence the voltage drop going through the ignition switch wiring. I pull my Ign sense from the yellow fan wire which also supplies power in accessory.
So I dug around the Internet and found this explanation on the operation of the Vacuum Pump. Although I was searching for JC4, this article didn't explicitly say JC4, however the wiring chart below states JC4.
Supplemental Brake Assist
The Supplemental Brake Assist (SBA) unit creates vacuum for the brake booster in case of a vacuum loss or low vacuum to the brake booster. The SBA consists of
• The sensor circuit board and pressure sensor
• The check valve manifold
• The vacuum pump
• The motor
When the vehicle is keyed ON, the SBA performs a self test by toggling the Supplemental Brake Assist Signal Circuit low for one second. The instrument panel cluster (IPC) recognizes this as an indication that the SBA is functional. If the IPC does not see this signal for five consecutive ignition cycles the Service Brake Booster Message is displayed. The SBA performs diagnostics at 16 Km/h (10 mph) under normal conditions, and before 16 Km/h (10 mph) if a low vacuum condition exists. The SBA then spins the motor and runs diagnostics to determine if the pump is operating and the SBA is functional. The SERVICE BRAKE BOOSTER message will display until the next ignition cycle if the unit is unable to maintain reduced power brake levels.
The SBA unit utilizes the ignition on signal from the generator to determine the engine is running and monitors speed using an input from the vehicle speed sensor. It also has an internal pressure sensor that compares the pressure inside the booster to the ambient pressure. If the vacuum drops below 18 cm/Hg (7 in/Hg) the REDUCED BRAKE POWER message is displayed and a 5 second timer is started. If the vacuum stays below 18 cm/Hg (7 in/Hg) for 5 seconds the SBA starts the pump. If the vacuum drops below 15 cm/Hg (6 in/Hg) the pump comes on immediately. Once the vacuum level increases to 23 cm/Hg (9 in/Hg) The pump shuts off. The REDUCED BRAKE POWER message continues to be displayed until the vacuum level reaches 25 cm/Hg (10 in/Hg). If the pump runs for one minute without the vacuum reaching 23 cm/Hg (9 in/Hg) the pump shuts off and the SERVICE BRAKE BOOSTER message is displayed.
The SBA assembly operates in two modes.
• Low Vacuum Mode -- The low vacuum mode can occur with the engine ON or OFF. The SBA determines the ON/OFF status by monitoring the regulator output on the engine ON circuit. This mode involves SBA pump activation and deactivation due to changes in vacuum detected by the pressure sensor.
- Low Vacuum Engine ON Mode -- The SBA will operate in reaction to changes to brake booster vacuum as monitored by the pressure sensor. This mode is normally active on power up if a valid engine ON signal is detected and a low vacuum condition is indicated for more than 5 seconds.
- Reduced Brake Power Mode -- When the booster vacuum drops below 18 cm/Hg (7 in/Hg) the SBA will start a 5 second timer. If the vacuum exceeds 18 cm/Hg (7 in/Hg) the timer stops and resets. After 5 seconds the pump activates and the REDUCED BRAKE POWER message is displayed.
- Immediate Pump Activation Mode -- When the booster vacuum drops below 15 cm/Hg (6 in/Hg) the REDUCED BRAKE POWER message is displayed and the pump is turned on.
- Pump Deactivation Mode -- The pump will be turned off when the booster vacuum exceeds 23 cm/Hg (9 in/Hg). The SBA will continue to display REDUCED BRAKE POWER until the booster vacuum exceeds 25 cm/Hg (10 in/Hg).
- Low Vacuum Engine Off -- The SBA will monitor the vacuum when the vehicle is above 8 Km/h (5 mph) and an engine OFF condition is detected. If the vehicle is below 8 Km/h (5 mph) and an engine OFF condition is detected the SBA will monitor the vacuum for 60 seconds
• Vacuum Augment (Engine OFF) Mode -- If the engine ON state changes to OFF after reaching 8 Km/h (5 mph) the SBA activates the pump for up to 60 seconds. After 60 seconds the pump shuts off and the SERVICE BRAKE BOOSTER message is displayed. If the engine ON signal is detected or the vehicle slows to below 8 Km/h (5 mph) before the pump times out. The pump shuts off and no message is displayed
I also found this information on the JC4 wiring including the additional pins.
http://www.gmcmhphotos.com/photos/misc/p64082-jc4-vacuum-pump-wiring.html
So from that wiring information, the line we have been calling +12V is an "Engine ON" signal. I can't tell if this "Engine ON" signal is an "Engine Running" signal, or simply Key ON.
However from my reading of its operation, it would seem that:
1) the vacuum is too low at 10" for our use...
2) the unit will time-out and shut down after 60 seconds of operation. Not exactly what we want if the engine quits while going down a long hill.
My eyes were starting to glaze over so maybe I missed something.
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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| Re: JC4 Vacuum pump operation and additional wires [message #326666 is a reply to message #326643] |
Sun, 03 December 2017 07:25  |
tphipps
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
Karma: 9
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Interesting read. Since GMC's do not have a vehicle speed sensor native to the vehicle, the cut-off at low speed does not occur. My installed JC4 provided enough boost to stop my GMC when the engine stopped. Was not moving very fast, trying to pull into traffic from a stop.
Thanks for the wiring diagram. Would be nice to use the connections as designed. Warning light would be interesting.
Tom
2012 Phoenix Cruiser model 2552
KA4CSG
[Updated on: Sun, 03 December 2017 07:30] Report message to a moderator |
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| Re: [GMCnet] JC4 Vacuum pump operation and additional wires [message #326668 is a reply to message #326643] |
Sun, 03 December 2017 07:58 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Bruce,
I was fortunate enough to attend Dave Lenzi's presentations on GMC brakes, he demonstrated the difference between the JC-4 and the Ford Azure brake vacuum pump and it was astounding!
I just found the "new" model (made of plastic) on RockAuto for $148.79 so I ordered one:
2012 FORD F-150 3.5L V6 Turbocharged
MOTORCRAFT BRPV30 Vacuum Pump $ 148.79 $ 0.00 1 $ 148.79
I'll report what I get when it arrives.
Also Les Burt noted:
******************************************************************************************************************************
----Original Message-----
From: Gmclist [mailto:gmclist-bounces@list.gmcnet.org] On Behalf Of Les Burt
Sent: Tuesday, March 14, 2017 7:49 AM
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] Anybody installed a Delco 20804130 Vacuum Pump??
The ford vacuum pump (aka Ford Azzure vacuum pump) that was listed on eBay a while back is still easily found. The early f150 ecoboost pick up uses the same pump. They were notorious for corrosion, so Ford revised the design and the latest version has a black composite body. You can buy them here in Canada at the Ford dealer for just a bit over $200cad.
Les Burt
Montreal
'75 Eleganza 26'
The EWIP (Eternal Work In Progress)
************************************************************************************************************************
Regards,
Rob M.
The Pedantic Mechanic
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808
-----Original Message-----
From: Gmclist [mailto:gmclist-bounces@list.gmcnet.org] On Behalf Of Bruce Hislop
Sent: Saturday, December 2, 2017 11:53 AM
To: gmclist@list.gmcnet.org
Subject: [GMCnet] JC4 Vacuum pump operation and additional wires
So I had the key on ACC last night pumping up the rear suspension to put blocks under the rear bogies for the winter. I noticed my JC4 brake vacuum
pump was cycling, and driving my Digipanel low voltage nuts, so I thought I'd check the voltage going to it.
I followed the main power(I thought) to the battery 12V terminal and measured the voltage. There was very little change there, so I pulled the fuse...
the pump continued to cycle. So I wondered if I got the Ignition and 12V wires reversed. I was under the assumption from wiring diagrams on the Net
that +12V was the main power wire from the Motor, and Ign was just a sense wire. But turns out the motor power is taken from the Ignition line, hence
the voltage drop going through the ignition switch wiring. I pull my Ign sense from the yellow fan wire which also supplies power in accessory.
So I dug around the Internet and found this explanation on the operation of the Vacuum Pump. Although I was searching for JC4, this article didn't
explicitly say JC4, however the wiring chart below states JC4.
Supplemental Brake Assist
The Supplemental Brake Assist (SBA) unit creates vacuum for the brake booster in case of a vacuum loss or low vacuum to the brake booster. The SBA
consists of
• The sensor circuit board and pressure sensor
• The check valve manifold
• The vacuum pump
• The motor
When the vehicle is keyed ON, the SBA performs a self test by toggling the Supplemental Brake Assist Signal Circuit low for one second. The instrument
panel cluster (IPC) recognizes this as an indication that the SBA is functional. If the IPC does not see this signal for five consecutive ignition
cycles the Service Brake Booster Message is displayed. The SBA performs diagnostics at 16 Km/h (10 mph) under normal conditions, and before 16 Km/h
(10 mph) if a low vacuum condition exists. The SBA then spins the motor and runs diagnostics to determine if the pump is operating and the SBA is
functional. The SERVICE BRAKE BOOSTER message will display until the next ignition cycle if the unit is unable to maintain reduced power brake
levels.
The SBA unit utilizes the ignition on signal from the generator to determine the engine is running and monitors speed using an input from the vehicle
speed sensor. It also has an internal pressure sensor that compares the pressure inside the booster to the ambient pressure. If the vacuum drops below
18 cm/Hg (7 in/Hg) the REDUCED BRAKE POWER message is displayed and a 5 second timer is started. If the vacuum stays below 18 cm/Hg (7 in/Hg) for 5
seconds the SBA starts the pump. If the vacuum drops below 15 cm/Hg (6 in/Hg) the pump comes on immediately. Once the vacuum level increases to 23
cm/Hg (9 in/Hg) The pump shuts off. The REDUCED BRAKE POWER message continues to be displayed until the vacuum level reaches 25 cm/Hg (10 in/Hg). If
the pump runs for one minute without the vacuum reaching 23 cm/Hg (9 in/Hg) the pump shuts off and the SERVICE BRAKE BOOSTER message is displayed.
The SBA assembly operates in two modes.
• Low Vacuum Mode -- The low vacuum mode can occur with the engine ON or OFF. The SBA determines the ON/OFF status by monitoring the regulator
output on the engine ON circuit. This mode involves SBA pump activation and deactivation due to changes in vacuum detected by the pressure sensor.
- Low Vacuum Engine ON Mode -- The SBA will operate in reaction to changes to brake booster vacuum as monitored by the pressure sensor. This mode is
normally active on power up if a valid engine ON signal is detected and a low vacuum condition is indicated for more than 5 seconds.
- Reduced Brake Power Mode -- When the booster vacuum drops below 18 cm/Hg (7 in/Hg) the SBA will start a 5 second timer. If the vacuum exceeds 18
cm/Hg (7 in/Hg) the timer stops and resets. After 5 seconds the pump activates and the REDUCED BRAKE POWER message is displayed.
- Immediate Pump Activation Mode -- When the booster vacuum drops below 15 cm/Hg (6 in/Hg) the REDUCED BRAKE POWER message is displayed and the pump
is turned on.
- Pump Deactivation Mode -- The pump will be turned off when the booster vacuum exceeds 23 cm/Hg (9 in/Hg). The SBA will continue to display REDUCED
BRAKE POWER until the booster vacuum exceeds 25 cm/Hg (10 in/Hg).
- Low Vacuum Engine Off -- The SBA will monitor the vacuum when the vehicle is above 8 Km/h (5 mph) and an engine OFF condition is detected. If the
vehicle is below 8 Km/h (5 mph) and an engine OFF condition is detected the SBA will monitor the vacuum for 60 seconds
• Vacuum Augment (Engine OFF) Mode -- If the engine ON state changes to OFF after reaching 8 Km/h (5 mph) the SBA activates the pump for up to 60
seconds. After 60 seconds the pump shuts off and the SERVICE BRAKE BOOSTER message is displayed. If the engine ON signal is detected or the vehicle
slows to below 8 Km/h (5 mph) before the pump times out. The pump shuts off and no message is displayed
I also found this information on the JC4 wiring including the additional pins.
http://www.gmcmhphotos.com/photos/misc/p64082-jc4-vacuum-pump-wiring.html
So from that wiring information, the line we have been calling +12V is an "Engine ON" signal. I can't tell if this "Engine ON" signal is an "Engine
Running" signal, or simply Key ON.
However from my reading of its operation, it would seem that:
1) the vacuum is too low at 10" for our use...
2) the unit will time-out and shut down after 60 seconds of operation. Not exactly what we want if the engine quits while going down a long hill.
My eyes were starting to glaze over so maybe I missed something.
--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
Hubler 1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
_______________________________________________
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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 Vacuum pump operation and additional wires [message #326687 is a reply to message #326686] |
Sun, 03 December 2017 14:34 |
Richard Denney
Messages: 920
Registered: April 2010
Karma: 9
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Senior Member |
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I didn't say it was right, I said that's what I found. It seemed like that
switch would turn on the supplemental pump much more aggressively than what
was described in the original post.
I would have thought, though, 16" or more vacuum enough to get good brake
boost.
Rick "whose old engine didn't exceed 15" vacuum at 4400 feet, with no
auxiliary pump, but who still had good brakes" Denney
On Sun, Dec 3, 2017 at 3:09 PM Emery Stora wrote:
> Why would you want to operate it at 16” hg and lower?
>
> I operate mine at higher than that and I am located at over 5000 feet
> elevation.
>
> Emery Stora
>
>> On Dec 3, 2017, at 12:13 PM, Richard Denney wrote:
>>
>> Rob,
>>
>> Please do. I am persuaded my current auxiliary pump isn't working and I
> was
>> out of the loop when people bought up the Azure pumps.
>>
>> Is Dave still offering his kit?
>>
>> Also--related: what are the options for silicone brake-booster vacuum
> hose?
>>
>> Rick "who found a switch that operates the pump at 16"Hg and lower"
> Denney
>>
>> On Sun, Dec 3, 2017 at 9:00 AM Rob Mueller
> wrote:
>>
>>> Bruce,
>>>
>>> I was fortunate enough to attend Dave Lenzi's presentations on GMC
> brakes,
>>> he demonstrated the difference between the JC-4 and the Ford Azure brake
>>> vacuum pump and it was astounding!
>>>
>>> I just found the "new" model (made of plastic) on RockAuto for $148.79
> so
>>> I ordered one:
>>>
>>> 2012 FORD F-150 3.5L V6 Turbocharged
>>> MOTORCRAFT BRPV30 Vacuum Pump $ 148.79 $ 0.00 1 $ 148.79
>>>
>>> I'll report what I get when it arrives.
>>>
>> --
>> Rick Denney
>> 73 x-Glacier 230 "Jaws"
>> Off-list email to rick at rickdenney dot com
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Rick Denney
73 x-Glacier 230 "Jaws"
Off-list email to rick at rickdenney dot com
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| Re: [GMCnet] JC4 Vacuum pump operation and additional wires [message #326688 is a reply to message #326687] |
Sun, 03 December 2017 14:45 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Senior Member |
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If you think you have good brakes at 16” you should try it at 18 or 19”. Dramatic improvement.
Dave Lenzi has demonstrated this in his seminars and it makes a remarkable difference.
Emery Stora
77 Kingsley
Frederick, CO
> On Dec 3, 2017, at 1:34 PM, Richard Denney wrote:
>
> I didn't say it was right, I said that's what I found. It seemed like that
> switch would turn on the supplemental pump much more aggressively than what
> was described in the original post.
>
> I would have thought, though, 16" or more vacuum enough to get good brake
> boost.
>
> Rick "whose old engine didn't exceed 15" vacuum at 4400 feet, with no
> auxiliary pump, but who still had good brakes" Denney
>
>> On Sun, Dec 3, 2017 at 3:09 PM Emery Stora wrote:
>>
>> Why would you want to operate it at 16” hg and lower?
>>
>> I operate mine at higher than that and I am located at over 5000 feet
>> elevation.
>>
>> Emery Stora
>>
>>> On Dec 3, 2017, at 12:13 PM, Richard Denney wrote:
>>>
>>> Rob,
>>>
>>> Please do. I am persuaded my current auxiliary pump isn't working and I
>> was
>>> out of the loop when people bought up the Azure pumps.
>>>
>>> Is Dave still offering his kit?
>>>
>>> Also--related: what are the options for silicone brake-booster vacuum
>> hose?
>>>
>>> Rick "who found a switch that operates the pump at 16"Hg and lower"
>> Denney
>>>
>>> On Sun, Dec 3, 2017 at 9:00 AM Rob Mueller
>> wrote:
>>>
>>>> Bruce,
>>>>
>>>> I was fortunate enough to attend Dave Lenzi's presentations on GMC
>> brakes,
>>>> he demonstrated the difference between the JC-4 and the Ford Azure brake
>>>> vacuum pump and it was astounding!
>>>>
>>>> I just found the "new" model (made of plastic) on RockAuto for $148.79
>> so
>>>> I ordered one:
>>>>
>>>> 2012 FORD F-150 3.5L V6 Turbocharged
>>>> MOTORCRAFT BRPV30 Vacuum Pump $ 148.79 $ 0.00 1 $ 148.79
>>>>
>>>> I'll report what I get when it arrives.
>>>>
>>> --
>>> Rick Denney
>>> 73 x-Glacier 230 "Jaws"
>>> Off-list email to rick at rickdenney dot com
>>> _______________________________________________
>>> GMCnet mailing list
>>> Unsubscribe or Change List Options:
>>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
> --
> Rick Denney
> 73 x-Glacier 230 "Jaws"
> Off-list email to rick at rickdenney dot com
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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| Re: [GMCnet] JC4 Vacuum pump operation and additional wires [message #326724 is a reply to message #326722] |
Mon, 04 December 2017 09:34 |
GMC.LES
Messages: 505
Registered: April 2014
Karma: -2
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Senior Member |
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The price has come down quite a bit for the azure pump. rockauto was selling them for just over $300 a while back, so the current price of $148 is a great deal. Thanks Rob M for updating us on the price.
Les Burt
Montreal
'75 Eleganza 26'
> On Dec 4, 2017, at 10:22 AM, Bruce Hislop wrote:
>
> Rob and Les,
>
> Thanks for the update on the new part number.
>
> Emery, I believe you posted some instructions a long time ago about increasing the JC4 vacuum limit settings. Counld you provide a link to that, or
> if it wasn't you, maybe someone has it book-marked. I tried to search for it but I didn't come up with anything.
>
> Thanks
>
> --
> Bruce Hislop
> ON Canada
> 77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
> Hubler 1 ton front end
> http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
> My Staff says I never listen to them, or something like that
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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| Re: JC4 Vacuum pump operation and additional wires [message #326725 is a reply to message #326722] |
Mon, 04 December 2017 10:14 |
 |
GMC Jimmy
Messages: 199
Registered: September 2016
Location: Niagara, Ontario
Karma: 2
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Senior Member |
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Hello Bruce, you have a PM,
Thanks,
Mike
RF_Burns wrote on Mon, 04 December 2017 10:22Rob and Les,
Thanks for the update on the new part number.
Emery, I believe you posted some instructions a long time ago about increasing the JC4 vacuum limit settings. Counld you provide a link to that, or if it wasn't you, maybe someone has it book-marked. I tried to search for it but I didn't come up with anything.
Thanks
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| Re: [GMCnet] JC4 Vacuum pump operation and additional wires [message #326728 is a reply to message #326725] |
Mon, 04 December 2017 11:19 |
Emery Stora
Messages: 959
Registered: January 2011
Karma: 4
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Senior Member |
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> On Dec 4, 2017, at 9:14 AM, Mike wrote:
>
> Hello Bruce, you have a PM,
> Thanks,
> Mike
>
>
> RF_Burns wrote on Mon, 04 December 2017 10:22
>> Rob and Les,
>>
>> Thanks for the update on the new part number.
>>
>> Emery, I believe you posted some instructions a long time ago about increasing the JC4 vacuum limit settings. Counld you provide a link to that,
>> or if it wasn't you, maybe someone has it book-marked. I tried to search for it but I didn't come up with anything.
>>
>> Thanks
>
>
RF Burns - I did not post anything about the JC4 vacuum pump. I am using a Azure pump which I bought from Dave Lenzi which has a separate vacuum control.
Emery Stora
77 Kingsley
Frederick, CO
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| Re: [GMCnet] JC4 Vacuum pump operation and additional wires [message #326881 is a reply to message #326685] |
Thu, 07 December 2017 23:06 |
|
USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Rick,
The pump arrived from RockAuto and I've posted some photos. It's not the same as the first one but it looks good to me. It's late
and I want to hit the hay so I've just posted some photos, tomorrow I'll make some comments and compare the two of them.
http://www.gmcmhphotos.com/photos/g7123-ford-vacuum-pump-232.html
Regards,
Rob M.
The Pedantic Mechanic
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808
-----Original Message-----
From: Gmclist [mailto:gmclist-bounces@list.gmcnet.org] On Behalf Of Richard Denney
Sent: Sunday, December 3, 2017 1:13 PM
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] JC4 Vacuum pump operation and additional wires
Rob,
Please do. I am persuaded my current auxiliary pump isn't working and I was
out of the loop when people bought up the Azure pumps.
Is Dave still offering his kit?
Also--related: what are the options for silicone brake-booster vacuum hose?
Rick "who found a switch that operates the pump at 16"Hg and lower" Denney
On Sun, Dec 3, 2017 at 9:00 AM Rob Mueller wrote:
> Bruce,
>
> I was fortunate enough to attend Dave Lenzi's presentations on GMC brakes,
> he demonstrated the difference between the JC-4 and the Ford Azure brake
> vacuum pump and it was astounding!
>
> I just found the "new" model (made of plastic) on RockAuto for $148.79 so
> I ordered one:
>
> 2012 FORD F-150 3.5L V6 Turbocharged
> MOTORCRAFT BRPV30 Vacuum Pump $ 148.79 $ 0.00 1 $ 148.79
>
> I'll report what I get when it arrives.
>
--
Rick Denney
73 x-Glacier 230 "Jaws"
Off-list email to rick at rickdenney dot com
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
_______________________________________________
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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: JC4 Vacuum pump operation and additional wires [message #326903 is a reply to message #326890] |
Fri, 08 December 2017 11:47 |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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Senior Member |
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RF_Burns wrote on Fri, 08 December 2017 08:14Larry,
You say you have switch to turn it on? So you don't have a vacuum switch to automate it's operation? or does the unit have an internal vacuum control switch?
From your photos, maybe you have the original metal version rather than the new style plastic one like RobM just got?
Thanks..
Yes, I have the original metal version. When that came available, I jumped on it right away. It has automated operation when the switch is on. So when the switch is on, it automatically comes on at a preset vacuum and turns off at a set upper limit. But the thing is noisy and every time you hit the brakes it comes on to keep the vacuum high..a source of irritation to me. With foot off the throttle, I have more than adequate vacuum to make full use of the vacuum booster for normal stopping. So because of the noise factor, I shut it off and it is there for use in case the engine just stops or when I'm pulling on the ramps. With this pump, there is no need for a vacuum reservoir. Recovery is so quick it will keep up 18-20in of vacuum even with pumping the brakes. Just what I do.
Larry 
78 Royale w/500 Caddy
Menomonie, WI.
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| Re: [GMCnet] JC4 Vacuum pump operation and additional wires [message #326904 is a reply to message #326903] |
Fri, 08 December 2017 11:55 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Senior Member |
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Hope you never get distracted
http://gmcmotorhome.info/addens.html#story
Noise is good
On Fri, Dec 8, 2017 at 9:48 AM Larry wrote:
> RF_Burns wrote on Fri, 08 December 2017 08:14
>> Larry,
>> You say you have switch to turn it on? So you don't have a vacuum
> switch to automate it's operation? or does the unit have an internal vacuum
>> control switch?
>> From your photos, maybe you have the original metal version rather than
> the new style plastic one like RobM just got?
>>
>> Thanks..
>
> Yes, I have the original metal version. When that came available, I
> jumped on it right away. It has automated operation when the switch is on.
> So
> when the switch is on, it automatically comes on at a preset vacuum and
> turns off at a set upper limit. But the thing is noisy and every time you
> hit
> the brakes it comes on to keep the vacuum high..a source of irritation to
> me. With foot off the throttle, I have more than adequate vacuum to make
> full use of the vacuum booster for normal stopping. So because of the
> noise factor, I shut it off and it is there for use in case the engine just
> stops or when I'm pulling on the ramps. With this pump, there is no need
> for a vacuum reservoir. Recovery is so quick it will keep up 18-20in of
> vacuum even with pumping the brakes. Just what I do.
>
>
> --
> Larry
> 78 Royale w/500 Caddy
> Menomonie, WI.
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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| Re: [GMCnet] JC4 Vacuum pump operation and additional wires [message #326910 is a reply to message #326903] |
Fri, 08 December 2017 13:05 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Senior Member |
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Larry - I believe I have the same setup as you. I bought it from Dave Lenzi at a rally.
Mine was also very noisy until I purchased rubber dampener mounts with studs at each end. After installing these it has been very quiet.
They screwed right into the Azure pump so they were probably metric.
Emery Stora
77 Kingsley
Frederick, CO
> On Dec 8, 2017, at 10:47 AM, Larry wrote:
>
> RF_Burns wrote on Fri, 08 December 2017 08:14
>> Larry,
>> You say you have switch to turn it on? So you don't have a vacuum switch to automate it's operation? or does the unit have an internal vacuum
>> control switch?
>> From your photos, maybe you have the original metal version rather than the new style plastic one like RobM just got?
>>
>> Thanks..
>
> Yes, I have the original metal version. When that came available, I jumped on it right away. It has automated operation when the switch is on. So
> when the switch is on, it automatically comes on at a preset vacuum and turns off at a set upper limit. But the thing is noisy and every time you hit
> the brakes it comes on to keep the vacuum high..a source of irritation to me. With foot off the throttle, I have more than adequate vacuum to make
> full use of the vacuum booster for normal stopping. So because of the noise factor, I shut it off and it is there for use in case the engine just
> stops or when I'm pulling on the ramps. With this pump, there is no need for a vacuum reservoir. Recovery is so quick it will keep up 18-20in of
> vacuum even with pumping the brakes. Just what I do.
>
>
> --
> Larry
> 78 Royale w/500 Caddy
> Menomonie, WI.
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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