Re: Can I run a Mechanical and Electric fuel pump together?
[Re: forphorty]
#1299136
09/07/12 11:52 PM
09/07/12 11:52 PM
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Joined: Mar 2005
Posts: 862 Iowa State fan
kilroy
super stock
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super stock
Joined: Mar 2005
Posts: 862
Iowa State fan
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If you used a dual pickup system 1 plumbed to the electric pump 2 and one with a one way valve on the pick up that goes to a Y then forward to the mechanical pump. That way the mechanical pump can suck through the one way valve line around the electric pump and when the electric pump is turned on it will pressurize the system forward to the mechanical pump but wont push fuel back to the fuel tank because of the one-way valve. But thats a lot of extra plumbing to do the same thing an electric pump will do by itself.
Plus if the mechanical pumps diaphragm ever ruptures while the electric pump is on it will start to dump raw fuel directly into the crank case!!!
1973 Charger, former SE, former auto
I'm not trying to be difficult, it comes naturally....
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Re: Can I run a Mechanical and Electric fuel pump together?
[Re: smokinwoody]
#1299138
09/08/12 12:13 AM
09/08/12 12:13 AM
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Joined: Oct 2003
Posts: 3,698 NE Oklahoma
Von
master
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master
Joined: Oct 2003
Posts: 3,698
NE Oklahoma
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Quote:
I have to laugh at a few of these...
No way it wont work...LOL...
72 RR, Pump gas 440, 452s, 3800 lbs, Corked, ET Radials,. 11.33@117.72.
Same car, bone stock 346s, 9.5 comp, baby solid. 12.24@110.
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Re: Can I run a Mechanical and Electric fuel pump together?
[Re: Dan Halen]
#1299139
09/08/12 12:15 AM
09/08/12 12:15 AM
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Joined: Oct 2003
Posts: 3,698 NE Oklahoma
Von
master
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master
Joined: Oct 2003
Posts: 3,698
NE Oklahoma
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Quote:
therefore would also need a good fuel pressure guage.....
..... should already have one anyway.
Um, why?????
72 RR, Pump gas 440, 452s, 3800 lbs, Corked, ET Radials,. 11.33@117.72.
Same car, bone stock 346s, 9.5 comp, baby solid. 12.24@110.
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Re: Can I run a Mechanical and Electric fuel pump together?
[Re: CrAzYMoPaRGuY]
#1299141
09/08/12 06:43 AM
09/08/12 06:43 AM
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Joined: Dec 2009
Posts: 21,066 in a cattle trailer down by th...
Guitar Jones
Paddle faster! I hear banjo music!
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Paddle faster! I hear banjo music!
Joined: Dec 2009
Posts: 21,066
in a cattle trailer down by th...
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I can't imagine the mechanical being able to suck through that Holley pump, but if you guys say you've done it who am I to say you can't?
"Come get your wife"
'92 D250 Club Cab CTD, 47RH conversion, pump tweaks, injectors, rear disc and hydroboost conversion. '74 W200 Crew Cab 360, NV4500, D44, D60 and NP205 divorced transfer case. Front and rear disc and hydroboost conversion. 2019 1500 Long Horn Crew Cab 4WD, 5.7 Hemi.
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Re: Can I run a Mechanical and Electric fuel pump together?
[Re: Guitar Jones]
#1299142
09/08/12 08:26 AM
09/08/12 08:26 AM
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Joined: Apr 2004
Posts: 12,339 somwhere
smokinwoody
I Live Here
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I Live Here
Joined: Apr 2004
Posts: 12,339
somwhere
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Quote:
I can't imagine the mechanical being able to suck through that Holley pump, but if you guys say you've done it who am I to say you can't?
if any of you ever disconnected the fuel line at the carb or in this case at the mechanical pump, you will find a very steady flowing stream of fuel..I mean flowing as if a pump was on!!!...and this is thru any electric pump in the rear...
so there is no effort on a mechanical fuel pump's part in sucking thru the electric pump...
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Re: Can I run a Mechanical and Electric fuel pump together?
[Re: smokinwoody]
#1299143
09/08/12 09:01 AM
09/08/12 09:01 AM
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Joined: Oct 2003
Posts: 21,345 Marysville, O-H-I-O
70Cuda383
Too Many Posts
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Too Many Posts
Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
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I don't understand why the desire to have 2 pumps. if you're going to put on an electric pump thats capable of delivering enough fuel on it's own, then why keep the mechanical pump? why not just bypass it, remove a few pounds of weight, and keep the fuel cooler.
what benefit do you GAIN by keeping the mechanical pump after adding an electric?
**Photobucket sucks**
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Re: Can I run a Mechanical and Electric fuel pump together?
[Re: SSAAHemiFan]
#1299147
09/08/12 02:06 PM
09/08/12 02:06 PM
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Joined: Jul 2006
Posts: 4,319 Puyallup, WA
StealthWedge67
master
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master
Joined: Jul 2006
Posts: 4,319
Puyallup, WA
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Carter 4862 mechanical pump being fed by stock 5/16" line into an 830cfm DP on a 451 here. Car weighs 3750 and runs 11.90's @ 113 mph with no fuel issues. I've had electric pumps before.... didn't like the noise and the hassle.
LemonWedge - Street heavy / Strip ready - 11.07 @ 120
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Re: Can I run a Mechanical and Electric fuel pump together?
[Re: 70Cuda383]
#1299148
09/08/12 02:28 PM
09/08/12 02:28 PM
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Joined: Nov 2006
Posts: 1,463 oklahoma
forphorty
pro stock
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pro stock
Joined: Nov 2006
Posts: 1,463
oklahoma
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Quote:
I don't understand why the desire to have 2 pumps. if you're going to put on an electric pump thats capable of delivering enough fuel on it's own, then why keep the mechanical pump? why not just bypass it, remove a few pounds of weight, and keep the fuel cooler.
what benefit do you GAIN by keeping the mechanical pump after adding an electric?
When i bought my first Holley blue back in the 80s, i heard that they weren't very reliable in a continuous duty(daily driver) application. So i kept the mech and turned the electric on when racing,etc. That first Holley blue lasted for years. When i switched from the factory 5/16 fuel line to 1/2 inch, i took off the mech. The Holley blue failed after about a year. Replaced it with a new one, it lasted a couple of years, bought another, it lasted a couple years. Switched to a red and it's been going for a long time . So... my long winded point is... Factory mechanical pumps are cheap, electric pumps are not. The life of an electric pump is greatly extended if it is rarely on. A mechanical pump has never left me stranded on the road, an electric has .Sure,a big ,fat high output mech would be fine for all my stuff but i like the electric for other reasons too.Like priming the system after the car has been sitting without having to crank the engine forever . Also as a way of checking for leaks after doing any fuel system work without having to start the engine.
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Re: Can I run a Mechanical and Electric fuel pump together?
[Re: SCATPACK 1]
#1299151
09/09/12 12:17 AM
09/09/12 12:17 AM
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Joined: Mar 2005
Posts: 862 Iowa State fan
kilroy
super stock
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super stock
Joined: Mar 2005
Posts: 862
Iowa State fan
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Last comments from me. Then you can do as you please. Regarding fuel coming through a Holley style vane pump. Yes fuel will go through them but it is very restricted, believe me I just had to change a electric pump when I broke its casing by installing a pipe thread to deep. (lesson learned there) The flow through the line when it is not attached to the pump is has A WHOLE LOT MORE FREE FLOW through it. When the line is attached to the pump it will run out but not much, as I could do my work with out worry about emptying the tank (or drowning). In regards to worrying about the longevity of electric v mechanical. I think it is a wash as mechanical pumps get weak and fail too. The only thing I can say for the noise is lots of rubber parts between the metal pieces of the pump/mounting areas.
1973 Charger, former SE, former auto
I'm not trying to be difficult, it comes naturally....
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Re: Can I run a Mechanical and Electric fuel pump together?
[Re: domingo]
#1299153
09/09/12 12:23 PM
09/09/12 12:23 PM
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Joined: Nov 2009
Posts: 2,275 Desert Tracker
HYPER8oSoNic
top fuel
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top fuel
Joined: Nov 2009
Posts: 2,275
Desert Tracker
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Quote:
Hi!
Last time I hit the track with my stock 71 440-6 car I think I had some fuel starvation issues....
When I was in 3rd gear and peak RPMs I had the motor die intermitently, kinda like if the cylinders were getting no spark....thing is, when the car is driven normally that never happens, so what Im guessing is that on a pass at wide open throttle Im sucking dry the 6 pack fuel bowls....am I thinking right???
Well, now to fix this I was wondering if I could run a Holley Blue pump (I already have it) out of the gas tank and then pump it through the stock mechanical pump.
I would like to avoid removing the stock mechanical if possible.
I would only turn the electric pump for ging down the 1/4 mile.
Can I do it like that?
Thanks!
D
To answer the questions - YES!!
This "old school" fuel system upgrade is timeless for carbuerated motors. Just wire the electric fuel pump with it's own on/off switch. Put the pump inline with the suction line from the tank and output side heading towards the input side of the mechanical pump. As a method of less flow restriction, try to upgrade to 3/8" steel fuel line, if you can. When you buy the electric pump, try to buy a "similar" (read: slightly higher)flow output pump than the mechanical. Example: 12psi output electric pump feeding into a 8psi mechanical pump. Got it? Remember, 6-packs NEED a lot of fuel, just like HEMIS or Max-Wedges!!
"Stupidity is Ignorance on Steroids" "Yeah, it's hopped to over 160" (quote by Kowalski in the movie Vanishing Point 1970 - Cupid Productions)
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