Can I run a Mechanical and Electric fuel pump together?

Posted By: Dan Halen

Re: Can I run a Mechanical and Electric fuel pump together? - 09/07/12 11:07 PM

Yes, you would have to use a regulator with the blue pump and

therefore would also need a good fuel pressure guage.....

..... should already have one anyway.

Posted By: 67Satty

Re: Can I run a Mechanical and Electric fuel pump together? - 09/07/12 11:16 PM

I think what people are trying to say is that if you run the electric back at the tank in series with the mechanical at the motor, the electric has to be on and pumping. I don't think there is any way to do your idea of just turning on the electric when you are at the strip. There would be no way for the mechanical to pull gas through the non-running electric pump in the back.

Posted By: keefe

Re: Can I run a Mechanical and Electric fuel pump together? - 09/07/12 11:23 PM

Quote:

Quote:

This is just a quick fix....OK...Ill just ditch the mechanical.

But Id like to understand why it is not adviseable....I have seen people do it with no problems.....

If you have the electric pump plumbed in series the mechanical is going to have to suck through that vane pump which isn't going to work very well at all.

I know there's no problem with the carter pumps, i got the idea from the old direct connection book (13 second build). I never tried it with a Holley pump.

Posted By: domingo

Re: Can I run a Mechanical and Electric fuel pump together? - 09/07/12 11:34 PM

It is not vapor locking...its got exh manifolds and the temperature here is very mild.

Everything on the car is NEW. Ignition is a newer electronic (stock).

I had some electrical trouble once while driving at night with the hi beams on because I have the original rebuilt 35 amp alternator and the headlights were on....and seems that the alternator didnt out out enough outup to charge the battery.....so I was cruising and all of a sudden the car started missing. I turned on the lights to just the running lights and waited it to recgarge and it was all OK again.

Now, the car doesnt ever miss.....But when I took it to the track it missed on 3rd top end. It didnt miss at all in 1st or 2nd. Made a couple more passes and the same thing.....it missed on the top end on 3rd.

So what Im guessing is that it starving for fuel at some point?????

Am I right????

This is why I want to put the Holley Blue electrical pump before the mechanical. I have seen it done before and the cars run fine,....

Now IM being told here not to do that, and just "build a re

Posted By: topside

Re: Can I run a Mechanical and Electric fuel pump together? - 09/07/12 11:34 PM

My Hemi car has a Carter electric + the hi-perf mechanical. It will run with just the mechanical, but it has 1/2" fuel line and the mech can't keep adequate pressure in a line that size after a couple miles. So I run both. Regulator after the mech pump, with a gauge. With a smaller line it might be OK, but I can't say for sure. Granted, the mech would have to pull through the vanes of an "off" electric pump, but mine will do that for a while until the pressure finally drops.

Posted By: Guitar Jones

Re: Can I run a Mechanical and Electric fuel pump together? - 09/07/12 11:38 PM

Quote:

It is not vapor locking...its got exh manifolds and the temperature here is very mild.

Everything on the car is NEW. Ignition is a newer electronic (stock).

I had some electrical trouble once while driving at night with the hi beams on because I have the original rebuilt 35 amp alternator and the headlights were on....and seems that the alternator didnt out out enough outup to charge the battery.....so I was cruising and all of a sudden the car started missing. I turned on the lights to just the running lights and waited it to recgarge and it was all OK again.

Now, the car doesnt ever miss.....But when I took it to the track it missed on 3rd top end. It didnt miss at all in 1st or 2nd. Made a couple more passes and the same thing.....it missed on the top end on 3rd.

So what Im guessing is that it starving for fuel at some point?????

Am I right????

This is why I want to put the Holley Blue electrical pump before the mechanical. I have seen it done before and the cars run fine,....

Now IM being told here not to do that, and just "build a re

You are not being told not to do that. You are being told you won't be able to just turn the electric pump on at the strip.

Posted By: gonzo440

Re: Can I run a Mechanical and Electric fuel pump together? - 09/08/12 01:55 AM

Yes you can run an electric in series with your mechanical. You can turn on the electric when you need it, like when you are at the track. I did this many years ago on my 440 6 Pack Challenger. I plumbed a Blue pump with regulator. (you can add the Red pump without the regulator) If it is falling on its face on the top end it is starving for fuel. Thats what mine was doing and this solved the problem. I still run my Hemi Challenger with this set up. Kind of an old school approach, but it works.

Posted By: Hemi Allstate

Re: Can I run a Mechanical and Electric fuel pump together? - 09/08/12 02:29 AM

Quote:

Yes you can run an electric in series with your mechanical. You can turn on the electric when you need it, like when you are at the track. I did this many years ago on my 440 6 Pack Challenger. I plumbed a Blue pump with regulator. (you can add the Red pump without the regulator) If it is falling on its face on the top end it is starving for fuel. Thats what mine was doing and this solved the problem. I still run my Hemi Challenger with this set up. Kind of an old school approach, but it works.

I did it using a Carter electric pump. I only turned it on to prime the system if the car had been sitting, and then whenever I wanted full power for a run, be it street or strip.

Posted By: moparjoe360.4

Re: Can I run a Mechanical and Electric fuel pump together? - 09/08/12 03:06 AM

My dad runs a parts store electric and a Carter high performance mechanical on his 6 pack with no issues but that's not a Holley blue, if u have that u don't need the mechanical pump.

Posted By: forphorty

Re: Can I run a Mechanical and Electric fuel pump together? - 09/08/12 03:20 AM

I ran a blue pump in series with a mech pump for years on a daily driver.The stock mech pump had no problem pulling fuel through the electric pump.Only had the electric on when racing or to fill the bowls of a dry carb.

Posted By: kilroy

Re: Can I run a Mechanical and Electric fuel pump together? - 09/08/12 03:52 AM

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!!!

Posted By: smokinwoody

Re: Can I run a Mechanical and Electric fuel pump together? - 09/08/12 03:54 AM

I have to laugh at a few of these...

for the last 15 years I have run both without a hitch and the only time I use the electric is when it was at the track...

it sucks through the electric just fine...the rear pump is a Holley black pump rated at 140GPH at 14psi...the front mechanical pump is a modified Speedway (Carter ) that Barry Grant made...its stats are 140GPH at 14psi...so a regulator is used and I do have a small supercharger .....

Posted By: Von

Re: Can I run a Mechanical and Electric fuel pump together? - 09/08/12 04:13 AM

Quote:

I have to laugh at a few of these...

No way it wont work...LOL...

Posted By: Von

Re: Can I run a Mechanical and Electric fuel pump together? - 09/08/12 04:15 AM

Quote:

therefore would also need a good fuel pressure guage.....

..... should already have one anyway.

Um, why?????

Posted By: CrAzYMoPaRGuY

Re: Can I run a Mechanical and Electric fuel pump together? - 09/08/12 09:13 AM

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Yes you can run an electric in series with your mechanical. You can turn on the electric when you need it, like when you are at the track. I did this many years ago on my 440 6 Pack Challenger. I plumbed a Blue pump with regulator. (you can add the Red pump without the regulator) If it is falling on its face on the top end it is starving for fuel. Thats what mine was doing and this solved the problem. I still run my Hemi Challenger with this set up. Kind of an old school approach, but it works.

I did it using a Carter electric pump. I only turned it on to prime the system if the car had been sitting, and then whenever I wanted full power for a run, be it street or strip.

EXACTLY what I did with my Demon, and EXACTLY what I am doing with my 1967 Charger!!

Posted By: Guitar Jones

Re: Can I run a Mechanical and Electric fuel pump together? - 09/08/12 10:43 AM

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?

Posted By: smokinwoody

Re: Can I run a Mechanical and Electric fuel pump together? - 09/08/12 12:26 PM

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...

Posted By: 70Cuda383

Re: Can I run a Mechanical and Electric fuel pump together? - 09/08/12 01:01 PM

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?

Posted By: Mr.Yuck

Re: Can I run a Mechanical and Electric fuel pump together? - 09/08/12 02:04 PM

I did it for a few years. I had a mild 440 w/ a Paxton. I used the eletric pump at the track or when I was going to get on it. I used the carter street/strip mech pump and their electric as well. If I had it to do over agin I'd just use a realy good mech or a straight up eletirc. Forget to turn on the electric and at about the 1000 foot mark your pistons start to burn up...AMHIK.
Not sure about you combo but I ran a 11:1, 548 soild cam 440-6 w/ a Stock (autozone) Hemi pump and 3/8 w/o issue. Maybe you need to raise your float levels, you could also have an electrical problem. I'd start w/ the basics before you add or spend money.

Posted By: domingo

Re: Can I run a Mechanical and Electric fuel pump together? - 09/08/12 04:05 PM

I just plumbed the electric blue pump and ditched the mechanical with a bloick off plate and added a regulator.-....like its supposed to be done.

Thanks for all the replies....now I know that it is doable to have a mechanical in betweenm the electric fuel pump and carbs.....but yes, why do it that way? Only thing would be the annoying sound of the electric pump on a car thats driven on the street...but oh well----

BTW the car runs great....Ill test it at the track tomorrow and Ill see if the problem's been solved!

Thanks!!!

Posted By: SSAAHemiFan

Re: Can I run a Mechanical and Electric fuel pump together? - 09/08/12 05:34 PM

holley red pump with mechanical pump here - red pump was only used in hot weather, racing, or to prime system

I installed a tee at the inlet and outlet of the electric pump with a bypass loop to help the pump run cooler and it allows fuel to pass thru easier then when the electric pump is off.

Car ran 10:50's, 3/8 line with no starvation issues - pump is 12 years old

Seems funky - but it works

Posted By: StealthWedge67

Re: Can I run a Mechanical and Electric fuel pump together? - 09/08/12 06:06 PM

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.

Posted By: forphorty

Re: Can I run a Mechanical and Electric fuel pump together? - 09/08/12 06:28 PM

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.

Posted By: 540DUSTER

Re: Can I run a Mechanical and Electric fuel pump together? - 09/08/12 10:11 PM

who the heck wants to listen to a loud ace holley pump in a street car if you don't have to.That is one noise I can't stand.But at the track you uncork them headers and turn that holley pump on and all you will hear is sweet music.

Posted By: SCATPACK 1

Re: Can I run a Mechanical and Electric fuel pump together? - 09/09/12 12:33 AM

Quote:

You can run an electric pump with the mechanical but you won't be able to turn it off and expect the car to still run.

I have this mechanical and electric set up on my 440 and do not use the electric pump except at the track. I have never had an issue this way. Before adding the high pressure mechanical, I wore out 2 Holley electric pumps trying to run them on the street. They just do not seem to hold up well for me with long drives/crusies. After I added the mechanical pump, I have not had any problems. I have not tried to run it at the track with just the mechanical pump. But i have used it a lot on the street with the electric pump off and no issues at all.
Good luck

Posted By: kilroy

Re: Can I run a Mechanical and Electric fuel pump together? - 09/09/12 04:17 AM

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.

Posted By: CrAzYMoPaRGuY

Re: Can I run a Mechanical and Electric fuel pump together? - 09/09/12 03:50 PM

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?

In MY Charger's case the reason was.... NOISE!!!!! I couldn't stand the sound of a noisy electric pump while cruising through town.

Posted By: HYPER8oSoNic

Re: Can I run a Mechanical and Electric fuel pump together? - 09/09/12 04:23 PM

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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!!

Posted By: 70Cuda383

Re: Can I run a Mechanical and Electric fuel pump together? - 09/10/12 01:24 PM

Quote:

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.

and the electric pump on my Dakota that puts out 50 psi is 15 years old, and has 100K street miles on it, and it doesn't cost that much more than a quality, aftermarket, low pressure carb fuel pump.

so there's no reason why an electric pump CAN'T provide reliability.

Was your system "dead headed" or did it have a return line to keep the fuel flowing? was there enough air flow to keep the pump from overheating? modern EFI pumps are submersed in fuel to keep them cool, and they have a regulator right at the tank that lets the fuel they pump continue to flow, the excess pressure dumps right back into the tank.

maybe the trick to getting an aftermarket "performance" carb pump to last is to keep it cool and let the fuel continue to flow vs dead heading it.

Posted By: forphorty

Re: Can I run a Mechanical and Electric fuel pump together? - 09/12/12 05:40 AM

Quote:

Quote:

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.

and the electric pump on my Dakota that puts out 50 psi is 15 years old, and has 100K street miles on it, and it doesn't cost that much more than a quality, aftermarket, low pressure carb fuel pump.

so there's no reason why an electric pump CAN'T provide reliability.

Was your system "dead headed" or did it have a return line to keep the fuel flowing? was there enough air flow to keep the pump from overheating? modern EFI pumps are submersed in fuel to keep them cool, and they have a regulator right at the tank that lets the fuel they pump continue to flow, the excess pressure dumps right back into the tank.

maybe the trick to getting an aftermarket "performance" carb pump to last is to keep it cool and let the fuel continue to flow vs dead heading it.

Your idea makes sense. I just ran the Holley "deadhead" regulator with no return line.

Can I run a Mechanical and Electric fuel pump together?