Home » Public Forums » GMCnet » Looking for electric fuel pump control
| Looking for electric fuel pump control [message #367174] |
Tue, 12 October 2021 12:12  |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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During the winter re-fit, I will be installing a pair of Carter 4070s.
I am mulling over how to control them so that when the main engine shuts down for any reason, they stop pumping.
I can think of lots of good reasons for this and trying to decide between alternator output (like I use for the electric choke), or lube oil pressure present.
They should both be reliable and the alternator is less invasive.
If someone has a better idea, I should like to hear it before I buy more parts.
Thank You
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| [GMCnet] Re: Looking for electric fuel pump control [message #367176 is a reply to message #367174] |
Tue, 12 October 2021 13:25  |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Matt,
The problem with the alternator supply is that if the alt. fails, you're
dead in the water 'til you bypass the isolator. The oil pressure switch
(from a Vega), on the other hand, only shuts down the pump when the engine
initiates the shutdown.
Ken H.
On Tue, Oct 12, 2021 at 1:12 PM Matt Colie wrote:
> During the winter re-fit, I will be installing a pair of Carter 4070s.
>
> I am mulling over how to control them so that when the main engine shuts
> down for any reason, they stop pumping.
> I can think of lots of good reasons for this and trying to decide between
> alternator output (like I use for the electric choke), or lube oil pressure
> present.
> They should both be reliable and the alternator is less invasive.
>
> If someone has a better idea, I should like to hear it before I buy more
> parts.
>
> Thank You
>
> Matt
> --
> Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL,
> GMCES
> Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum
> Brakes with Applied Control Arms
> SE Michigan - Near DTW - Twixt A2 and Detroit
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Re: Looking for electric fuel pump control [message #367180 is a reply to message #367176] |
Tue, 12 October 2021 15:42 |
Christo
Messages: 109
Registered: April 2019
Location: Weymouth, MA
Karma: 0
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Senior Member |
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...and even if you jumper the outer terminals of the isolator (or have a combiner), the alternator output feed would still be dead along with your fuel pumps. Wiring in an override switch would work, but it would carry the risk of leaving the switch in the override position, thus defeating the safety feature. At least if such a switch were illuminated you'd be likely to notice when it was in the override position.
I vote for using oil pressure. That's how the PO set up the aux electric fuel pump on my coach, using an oil pressure switch and a relay so that the pump will only run when switched on and there's oil pressure. The only thing I don't like is that I have a "tree" coming out of the oil pressure port with one switch and two senders (for aftermarket dash gauge and DigiPanel. It's ugly.
Some folks have also used a "crash sensor" switch based on an accelerometer -- I don't know the OEM brand / part number -- to kill the pumps if there's an accident.
Christo Darsch
GMC Nor'easters
1977 Eleganza II - "The Komet"
3.50 Power Drive, Disc Brakes, Alcoas
Weymouth, MA
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| [GMCnet] Re: Looking for electric fuel pump control [message #367183 is a reply to message #367177] |
Tue, 12 October 2021 17:54 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Matt,
Here's a list of the applications for what I'm in the habit of calling a
"Vega Switch":
https://1drv.ms/t/s!Ai1vXmS6UF0_gotF3OLJPne3NDCh2w
And here is the diagram of my pumps, as I drew it in 2010:
https://1drv.ms/b/s!Ai1vXmS6UF0_gotLYbNzGmIJMNYfvA?e=md8n9j
Ken H.
On Tue, Oct 12, 2021 at 3:15 PM Matt Colie wrote:
> Ken Henderson wrote on Tue, 12 October 2021 14:25
>> Matt,
>>
>> The problem with the alternator supply is that if the alt. fails, you're
> dead in the water 'til you bypass the isolator. The oil pressure switch
>> (from a Vega), on the other hand, only shuts down the pump when the
> engine initiates the shutdown.
>>
>> Ken H.
>
> Ken,
> I like the idea and the Vega switch had the other function of of powering
> up the pump with ignition on. But that was 50 years ago and I really don't
> remember how it all worked and I don't have another place to add a
> pressure switch. All the regular pressure switches are normally open.
> Anybody have any diagrams or part numbers?
> Thanks
> Matt
> --
> Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL,
> GMCES
> Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum
> Brakes with Applied Control Arms
> SE Michigan - Near DTW - Twixt A2 and Detroit
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: Looking for electric fuel pump control [message #367200 is a reply to message #367174] |
Thu, 14 October 2021 03:43 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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The wiring diagram you referenced will work OK but the 10 gauge wire and 30 amp fuse are a little over kill for a pump that draws a little under 2 amps. I have a 3 amp fuse in mine and have never blown it. I would rather blow a fuse if the motor ever locked up than have the pump sit there getting hot and burning up. Especially Since it has lots of gasoline available to help feed the fire.
Ken B.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| [GMCnet] Re: Looking for electric fuel pump control [message #367201 is a reply to message #367189] |
Thu, 14 October 2021 07:04 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Matt,
I really hate being a nit-picker, but just to keep everyone straight: That
arrangement of diodes provides OR logic, not AND. In other words, the
circuit is activated when one OR another of the switches is closed.
To provide an AND function, switches merely need to be wired in series.
You knew all that, but some readers may not.
Ken H.
On Wed, Oct 13, 2021 at 10:14 AM Matt Colie wrote:
> Ken Henderson wrote on Tue, 12 October 2021 18:54
>> Matt,
>>
>> Here's a list of the applications for what I'm in the habit of calling a
>> "Vega Switch":
>> https://1drv.ms/t/s!Ai1vXmS6UF0_gotF3OLJPne3NDCh2w
>>
>> And here is the diagram of my pumps, as I drew it in 2010:
>> https://1drv.ms/b/s!Ai1vXmS6UF0_gotLYbNzGmIJMNYfvA?e=md8n9j
>>
>> Ken H.
>
> Ken,
>
> Your diagram has lots of good ideas that I may borrow. The diode AND gate
> is a great start.
>
> What I have been hoping to locate is the Vega (We had one back then) fuel
> pressure relay with an "On Delay" so it powers the fuel pump for a given
> time when the ignition is turned on. I have found references, but nothing
> with a working part number. That could eliminate the "prime" switch.
>
> I really like the idea of the alternator output as a signal because it
> exists. It works great for my electric choke.
>
> Fortunately, I have a lot of time before I tear into the coach for the
> winter re-fit.
>
> Matt
> --
> Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL,
> GMCES
> Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum
> Brakes with Applied Control Arms
> SE Michigan - Near DTW - Twixt A2 and Detroit
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Re: Looking for electric fuel pump control [message #367206 is a reply to message #367201] |
Thu, 14 October 2021 09:06 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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Ken Henderson wrote on Thu, 14 October 2021 08:04Matt,
I really hate being a nit-picker, but just to keep everyone straight: That arrangement of diodes provides OR logic, not AND. In other words, the circuit is activated when one OR another of the switches is closed.
To provide an AND function, switches merely need to be wired in series.
You knew all that, but some readers may not.
Ken H.
OOps,
Thanks Ken
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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