Need a GOOD relay to run my two fuel pumps. As my new China one just quit.

Bob Dunahugh

New member
Sep 17, 2012
2,784
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Put in another new fuel pump. Didn't even get out of the drive when the new relay died. This relay is a small black one from Auto Zone. Any suggestions? Bob Dunahugh
 
Lots more Scotch. (Grin) But seriously, that pump shouldn't draw more than
12 or 15 amps. Most of those little cube relays have their amperage rating
stamped on them. I have a bunch of them, most are rated for 40 amps. But,
does the pump run continously or does it start and stop to maintain a
certain pressure. That might tax a relay beyond its rating by inducing a
collapsing magnetic field internally. Just my wild assed guess.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

> Put in another new fuel pump. Didn't even get out of the drive when the
> new relay died. This relay is a small black one from Auto Zone. Any
> suggestions? Bob Dunahugh
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I suggest that you purchase a Bosch relay. Many of the cheaper “black boxes” don’t hold up.

Emery Stora
77 Kingsley
Frederick, CO

>
> Put in another new fuel pump. Didn't even get out of the drive when the new relay died. This relay is a small black one from Auto Zone. Any suggestions? Bob Dunahugh
> _______________________________________________
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> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Bob,

Here you go:

http://www.viaircorp.com/electrical/relays/

If you buy the 80 amp model I'd say you've got serious overkill!

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] On Behalf Of Bob Dunahugh
Sent: Friday, September 8, 2017 4:31 PM
To: gmclist
Subject: [GMCnet] Need a GOOD relay to run my two fuel pumps. As my new China one just quit.

Put in another new fuel pump. Didn't even get out of the drive when the new relay died. This relay is a small black one from Auto
Zone. Any suggestions? Bob Dunahugh
 
If you are using 1 relay to drive 2 pumps, I would split the load and use another relay for each additional pump. Less communication of the power
fluctuations generated by each pump that way and also makes troubleshooting much easier with each pump having a direct line to the battery.
--
Terry Kelpien

ASE Master Technician

73 Glacier 260

Smithfield, Va.
 
You might try something from Cole Hersee. A primary supplier to all the truck manufacturers.

----- Original Message -----

From: "Rob Mueller"
To: "gmclist"
Sent: Friday, September 8, 2017 3:24:36 PM
Subject: Re: [GMCnet] Need a GOOD relay to run my two fuel pumps. As my new China one just quit.

Bob,

Here you go:

http://www.viaircorp.com/electrical/relays/

If you buy the 80 amp model I'd say you've got serious overkill!

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] On Behalf Of Bob Dunahugh
Sent: Friday, September 8, 2017 4:31 PM
To: gmclist
Subject: [GMCnet] Need a GOOD relay to run my two fuel pumps. As my new China one just quit.

Put in another new fuel pump. Didn't even get out of the drive when the new relay died. This relay is a small black one from Auto
Zone. Any suggestions? Bob Dunahugh

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Terry. I'm not running both pumps at the same time. I've had the main/aux tank valve die on the road. So I wanted to have a backup fuel pump already installed. And get rid of that gas switch over valve. So now I have the dash gas tank switch operate a rely. The relay now runs the main tank pump till I switch over to the Aux tank pump. This setup works for EFI, or Carb systems. I still have my entire carb system in place with the Carter 4070 pump installed on the outside of the main frame. This pump only takes gas out of the main tank. Now I can't have tank valve fail because I don't have one. And if I have a main tank pump fails. I just turn on the aux tank pump. If all of my EFI fails. I can go back to the carb. And with the carb in place. I just won't have a vacuum advanced distributor. But I'll get home. And right now. I'm SO SO glad I didn't put my fuel pumps in the gas tanks. As I can change a fuel pump in 20 minutes.

Bob Dunahugh
 
Just about any 12 volt relay will do. A fuel pump is a low current device. It does not have any high current start up requirements. My Cater P4070
draws less than 2 amps. I have a 3 amp fuse in line with it and have never blown it. I'm not quite sure of your wiring set up, but you can always
go to the junk yard and get a few relays out of GM vehicles (or other brands) and wire one up with some small push on connectors.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
> If you are using 1 relay to drive 2 pumps, I would split the load and use another relay for each additional pump. Less communication of the power
> fluctuations generated by each pump that way and also makes troubleshooting much easier with each pump having a direct line to the battery.

The relay Bob is using (or hopefully is using) is a 5 pin. When the relay is not energized the 12v from the EFI (which should be triggered by a
normal relay) goes into the 5 pin relay then out to the main tank pump. When the relay is energized by the selector switch (switching to Aux), then
the relay will switch the 12v to the other lug which should be connected to the Aux. Pump.

Bob, is this the way you have wired your setup? I think this is what we have discussed as the best way to wire the main and aux pumps.

--
Randy & Margie
'77 Eleganza II '403'
Battlefield, MO
 
Randy. I did go with your suggestion with the 5 pin relay. Thank you. The pumps are running with about 4 Amps. The rely is rated at 40 Amps. I just love this setup. Should have installed that setup when I had the carb. And Randy. My idle in drive is now at 725 RPMs. Is that close enough to keep my TB happy? Bob Dunahugh One happy sucker.

________________________________
From: Bob Dunahugh
Sent: Saturday, September 9, 2017 11:14 AM
To: gmclist
Subject: RE: Need a GOOD relay to run my two fuel pumps. As my new China one just quit.

Terry. I'm not running both pumps at the same time. I've had the main/aux tank valve die on the road. So I wanted to have a backup fuel pump already installed. And get rid of that gas switch over valve. So now I have the dash gas tank switch operate a rely. The relay now runs the main tank pump till I switch over to the Aux tank pump. This setup works for EFI, or Carb systems. I still have my entire carb system in place with the Carter 4070 pump installed on the outside of the main frame. This pump only takes gas out of the main tank. Now I can't have tank valve fail because I don't have one. And if I have a main tank pump fails. I just turn on the aux tank pump. If all of my EFI fails. I can go back to the carb. And with the carb in place. I just won't have a vacuum advanced distributor. But I'll get home. And right now. I'm SO SO glad I didn't put my fuel pumps in the gas tanks. As I can change a fuel pump in 20 minutes.

Bob Dunahugh
 
> Put in another new fuel pump. Didn't even get out of the drive when the new relay died. This relay is a small black one from Auto Zone. Any
> suggestions? Bob Dunahugh

Get your failed one open. Bring it to Elkhart. I had one of these cube relays fail. I popped it open and found an itty bitty relay inside the case.
No way was that relay good for 30/40 amps.
--
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI
 
> Randy. I did go with your suggestion with the 5 pin relay. Thank you. The pumps are running with about 4 Amps. The rely is rated at 40 Amps. I
> just love this setup. Should have installed that setup when I had the carb. And Randy. My idle in drive is now at 725 RPMs. Is that close enough to
> keep my TB happy? Bob Dunahugh One happy sucker.

Bob,

Yes, that idle should be good. When you get here to Elkhart, I can put a monitor on and we can do the final adjustment of idle to get it dialed in
properly. I can also check your fueling parameters and make any additional tweaks that might help it run even better.
--
Randy & Margie
'77 Eleganza II '403'
Battlefield, MO
 
Mens mall is where I get relays. OEM relays are generally high quality, and they're like a buck or 2 at the pick n pull.

Bosch ones are ok... But I've replaced more than a few few on BMWs, Audis and VWs over the years... I prefer the Denso ones. I've been driving
Mazda RX7s for 27 years now, and I currently own 4. None are my daily drivers anymore, but all have the original relays, and I've never replaced even
one. Including my 85 which has 290K miles on it. Same goes for my friends with these cars. Heck, even my 74 Rotary Pickup, which I've owned for 10
years now, has all the original relays. However, the 74 has the old style with the metal caps and big copper coils that are more "serviceable" than
the modern ones, but are heavy, and no better than the newer ones... at least, 30 years in they haven't proved to be so far.

Hard to beat 70s, 80s and 90s Japanese electronics for durability. Can't comment on the newer stuff, as it's still unproven, IMO.

FWIW, all modern GM vehicles I know of run Denso ignition components from the factory...

I have a whole box full of relays I've pulled off of Mazda's in JYs over the years. Used them on all sorts of projects... Lighting, electric fan
setups, etc. I generally clip a nice section of the plug harness as well for splicing. When Mazda mounts a relay out in the elements, they generally
include a rubber boot that goes over the relay and part of the harness as well. Nice to have if you also plan on mounting outside.

Like this:

http://www.ebay.com/itm/FA0151939-New-Genuine-Headlamp-Light-Retractor-Relay-OEM-For-1984-85-Mazda-RX-7-/182382442682?fits=Model%3ARX-7&hash=item2a76d738ba:g:cscAAOSwo4pYSbvb&vxp=mtr

They're expensive if you buy them new, (which may be why they last so long)... But like a a couple bucks at the JY.

--
Mark S. '73 Painted Desert,
Manny 1 Ton Front End,
Howell Injection,
Leigh Harrison 4bag and Rear Brakes,
Fort Worth, TX
 
Thanks so much for you help. I'll have my extra ECM that you programed the chip with my. Would it be much to program that ECM as a backup? We're leaving in the AM tomorrow. Bob
 
> Thanks so much for you help. I'll have my extra ECM that you programed the chip with my. Would it be much to program that ECM as a backup? We're
> leaving in the AM tomorrow. Bob
>
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No problem...

--
Randy & Margie
'77 Eleganza II '403'
Battlefield, MO