| Installing Small Electric Fuel Pump- anyone? [message #354845] |
Mon, 18 May 2020 14:15  |
GEMRECS
Messages: 34
Registered: October 2008
Karma: -1
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Somewhere I found someone had installed a small electric fuel pump between the fuel selector VALVE and the mechanical pump like an auxiliary device.
My GMC was not getting fuel up to the pump, so I have dropped the tanks, installed all new rubber hoses and new hybrid fuel senders.
I will report on these senders if they work, but I wish to try this 4-8 psi pump and I need a model number and connection information to do this.
I read about the connection to the oil pressure sending unit, but need on/off input or how to connect to ignition switch while also having safety using the oil pressure sending unit.
My fuel gauges at the dash may not be working either-will see.
Michael Bozardt
1974 GMC Motorhome probably Canyon Lands (yellow)
1972 Datsun 240-Z
1998 BMW M3 (16,000 miles)
[Updated on: Mon, 18 May 2020 14:19] Report message to a moderator |
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| Re: Installing Small Electric Fuel Pump- anyone? [message #354849 is a reply to message #354845] |
Mon, 18 May 2020 16:45  |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Michael,
After trying several inexpensive push through solenoid type pumps, I finally wized up and installed a Carter 4070 on the outside of my frame along with relocating the fuel lines, filter, and selector valve.
I did NOT follow the usual safety protocol of installing it through an oil pressure switch but it is probably an excellent idea. Mine is wired through a relay that is triggered by the tank selector switch and it also pumps through the mechanical pump (BAD, I know).
I know the risks of running it this way, and will probably get around to correcting the situation eventually (if it's not too late by then).
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: Installing Small Electric Fuel Pump- anyone? [message #354853 is a reply to message #354845] |
Mon, 18 May 2020 20:55 |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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The carter 4070 that carl suggests is the most reliable one I know of. Used on vw buggies and my old wagoneer, Never failed.
However they are kinda a pain to mount on a gmc in my opinion.
I say go with a basic facet cube pump. Buy off amazon. 4-8 psi.
Just put a flat mounting plate accross the frame or it can even be screwed up to the floor. Just use it occationally. Like everytime you start the gmc. Switch to aux. start. And switch back. You hear it pumping and will know a good sound vs a bad sound. Dont go a year and switch to aux and expect it to all work.
THere is a photo in my write up:
http://lqqkatjon.blogspot.com/2017/04/fuel-lines.html?m=1
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
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| Re: Installing Small Electric Fuel Pump- anyone? [message #354905 is a reply to message #354865] |
Wed, 20 May 2020 00:17 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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roy1 wrote on Tue, 19 May 2020 11:25Is there a reason for not using 1 pump for each tank?
There is no reason not to do it. Many have done it. My OEM system works fine so I have no bothered to do it and "upgrade" to that system.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Installing Small Electric Fuel Pump- anyone? [message #355101 is a reply to message #354845] |
Mon, 25 May 2020 03:47 |
Clark76
Messages: 62
Registered: February 2010
Karma: -2
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I installed a Supplemental Electric Carter 4070 Fuel pump on my 1976 GMC.
The pump is activated by pressing and holding a spring loaded momentary button for 10 to 20 seconds (With the Tank Selector Switch also set to AUX) on the dash to temporarily boost fuel to the engine after it has been sitting for an extended period of time to reduce cranking time on start up.
The Fuel Filter and Pump are located inside the frame rail on the drivers side in front of the fuel tanks. When the MAIN/AUX fuel selector is set to AUX and the Fuel Pump Momentary Button is pressed in the drivers compartment, fuel is moved from the AUX tank through the Fuel Filter, then to the Carter 4070 pump, and then through the Fuel Selector Solenoid, then to the inlet of the manual fuel pump on the engine.
Alternatively, with the Tank Selector Set to AUX, (and the momentary Fuel Pump button not activated), Fuel from the AUX Tank can "Free Flow" from the AUX tank through the Fuel Filter then through a check-valve bypass (bypassing the electric fuel pump) to the inlet of the Mechanical fuel pump on the engine.
Alternatively, with the Tank Selector Set to MAIN, (and the momentary Fuel Pump not activated), Fuel from the Main Tank can "Free Flow" from the Main Tank through the Fuel Selector Solenoid, then to the inlet of the manual fuel pump on the engine.
Photo's of the installation can be seen on the following link:
http://www.gmcmhphotos.com/photos/g7300-electric-fuel-pump.html
[Updated on: Mon, 25 May 2020 09:59] Report message to a moderator |
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| Re: Installing Small Electric Fuel Pump- anyone? [message #355112 is a reply to message #355101] |
Mon, 25 May 2020 13:02 |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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Clark76 wrote on Mon, 25 May 2020 03:47I installed a Supplemental Electric Carter 4070 Fuel pump on my 1976 GMC.
The pump is activated by pressing and holding a spring loaded momentary button for 10 to 20 seconds (With the Tank Selector Switch also set to AUX) on the dash to temporarily boost fuel to the engine after it has been sitting for an extended period of time to reduce cranking time on start up.
IMO, REDUCING the cranking time on an engine that has been sitting for an extended period is NOT really a good thing. During that extended period, gravity will pull oil off of bearing surfaces, leaving them dry and exposed to damage when the engine starts. Long cranking in this situation gives the oil pump time to prime all bearing surfaces with oil so that adequate lubrication is available when the engine finally fires up. I have fuel injection on my Cadillac engine. When sitting for long periods, I will pull the fuse for the FI and the coil wire, and crank the motor until I see oil pressure. I have found that it can take 30 seconds or more before the oil pressure gauge shows pressure indicting to me that oil is flowing to the bearings. Personally, I would not want my engine to run for 30 seconds without lubrication to the bearings. Is it hard on the starter, yes. But starters are cheaper and easier to replace than an engine rebuild. Again, JMHO
Larry 
78 Royale w/500 Caddy
Menomonie, WI.
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| Re: Installing Small Electric Fuel Pump- anyone? [message #355115 is a reply to message #355112] |
Mon, 25 May 2020 15:41 |
Clark76
Messages: 62
Registered: February 2010
Karma: -2
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Good Point.
Without the supplemental low pressure fuel boost, my initial cranking time after extended lack of RV use was well over 30 seconds after multiple attempts.
With the set-up now, extended cold start is more reasonable, more in line with the suggested 30 second target.
Cold Start after sitting for a few days at a campground for example, supplemental boost is not needed.
Warm start is quick and great. No supplemental boost required.
Hot start is finicky. Likely due to intermittent vapor lock issues which seems to be mitigated with another short boost from the Supplemental Carter 4070 electric fuel pump from time to time.
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