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Can I run a Mechanical and Electric fuel pump together? #1299114
09/07/12 04:21 PM 09/07/12 04:21 PM
Joined: Jan 2003
Posts: 9,670
Lima, Peru
domingo Offline OP
EL Master
domingo  Offline OP
EL Master

Joined: Jan 2003
Posts: 9,670
Lima, Peru
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

7368929-cuda!!!!.jpg (211 downloads)
Re: Can I run a Mechanical and Electric fuel pump together? [Re: domingo] #1299115
09/07/12 04:37 PM 09/07/12 04:37 PM
Joined: Dec 2009
Posts: 20,640
in a cattle trailer down by th...
G
Guitar Jones Offline
Paddle faster! I hear banjo music!
Guitar Jones  Offline
Paddle faster! I hear banjo music!
G

Joined: Dec 2009
Posts: 20,640
in a cattle trailer down by th...
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 would suggest just building a real fuel system for it and get rid of the mechanical pump.

"Follow me the wise man said, but he walked behind"


'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. Rear disc and hydroboost conversion.
2019 1500 Long Horn Crew Cab 4WD, 5.7 Hemi.
Re: Can I run a Mechanical and Electric fuel pump together? [Re: Guitar Jones] #1299116
09/07/12 05:35 PM 09/07/12 05:35 PM
Joined: Sep 2003
Posts: 10,645
Houston, Tx
A
AlexP Offline
I Live Here
AlexP  Offline
I Live Here
A

Joined: Sep 2003
Posts: 10,645
Houston, Tx
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 would suggest just building a real fuel system for it and get rid of the mechanical pump.



I would ditch the mechanical pump all together.

My Build thread: Let the hemi swap begin!

1968 wanna be pro touring whatchamacallit with some fancy stuff and a new roof skin.
Re: Can I run a Mechanical and Electric fuel pump together? [Re: AlexP] #1299117
09/07/12 05:43 PM 09/07/12 05:43 PM
Joined: Jan 2003
Posts: 9,670
Lima, Peru
domingo Offline OP
EL Master
domingo  Offline OP
EL Master

Joined: Jan 2003
Posts: 9,670
Lima, Peru
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.....
Re: Can I run a Mechanical and Electric fuel pump together? [Re: domingo] #1299118
09/07/12 05:52 PM 09/07/12 05:52 PM
Joined: Aug 2007
Posts: 1,271
Vista, California
6
67Satty Offline
pro stock
67Satty  Offline
pro stock
6

Joined: Aug 2007
Posts: 1,271
Vista, California
Sometimes the trouble you are having is from the fuel getting hot and vapor locking. If you still running the mechanical, you are still running the fuel through something next to the hot motor.

On the other hand, I'm running a Carter M6903 mechanical pump only on my 440 at the strip with no problems.

If you were to ask for a show of hands all the people running a good mechanical pump only at the strip, you'd probably get quite a few replies from people with way faster stuff than my high 12-second street car.
Re: Can I run a Mechanical and Electric fuel pump together? [Re: 67Satty] #1299119
09/07/12 05:57 PM 09/07/12 05:57 PM
Joined: Mar 2008
Posts: 264
Westbury, NY
C
cowbay Offline
enthusiast
cowbay  Offline
enthusiast
C

Joined: Mar 2008
Posts: 264
Westbury, NY
Years ago there were a few classes that actually required both mechanical and electrical fuel pumps

"Alcohol is for drinking, gas is for cleaning parts, and nitro is for racing!" original author unknown, used by Gene Adams and Don Garlits among others
Re: Can I run a Mechanical and Electric fuel pump together? [Re: 67Satty] #1299120
09/07/12 06:23 PM 09/07/12 06:23 PM
Joined: Jan 2003
Posts: 9,670
Lima, Peru
domingo Offline OP
EL Master
domingo  Offline OP
EL Master

Joined: Jan 2003
Posts: 9,670
Lima, Peru
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 real fuel system".

I want to know why it is NOT adviseable to do so, as I have seen it done and work....

I know I can put an Aeromotive fuel pump 10 AN Lines and all that and forget it, but this is not a car where I want to do that! I have such a fuel system in my race car project....I wanna know what can I do to fix this quick so I can go racingf on sunday!!!

And why are you saying that I should not expect to see the engine keep running after I turn off the electrical pumpˇˇˇˇ????

Thanks]!

D
Re: Can I run a Mechanical and Electric fuel pump together? [Re: domingo] #1299121
09/07/12 06:39 PM 09/07/12 06:39 PM
Joined: Jan 2003
Posts: 403
southern Maryland
K
keefe Offline
mopar
keefe  Offline
mopar
K

Joined: Jan 2003
Posts: 403
southern Maryland
on my gtx i use the carter (street strip ) mechanical and the carter electric pump at the tank. I only use the electric at the track, it had the stock 5/16 gas line. car use to go high 12's to low 13's, was my daily driver. The electric pump finally crapped out a few months ago after 30 years..LOL
With out the electric the car would dang near cut off when you shifted in to third.
Keefe

Last edited by keefe; 09/07/12 06:44 PM.
1971 duster twister 440, 3380#,509 M/P hyd,906's,full Exhaust,11.06@117.46 1/4,6.95@ 97.03 1/8,1.497 60ft.....
Re: Can I run a Mechanical and Electric fuel pump together? [Re: domingo] #1299122
09/07/12 06:44 PM 09/07/12 06:44 PM
Joined: Dec 2009
Posts: 20,640
in a cattle trailer down by th...
G
Guitar Jones Offline
Paddle faster! I hear banjo music!
Guitar Jones  Offline
Paddle faster! I hear banjo music!
G

Joined: Dec 2009
Posts: 20,640
in a cattle trailer down by th...
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.

"Follow me the wise man said, but he walked behind"


'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. Rear disc and hydroboost conversion.
2019 1500 Long Horn Crew Cab 4WD, 5.7 Hemi.
Re: Can I run a Mechanical and Electric fuel pump together? [Re: Guitar Jones] #1299123
09/07/12 06:55 PM 09/07/12 06:55 PM
Joined: Jan 2003
Posts: 9,670
Lima, Peru
domingo Offline OP
EL Master
domingo  Offline OP
EL Master

Joined: Jan 2003
Posts: 9,670
Lima, Peru
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.



but the mechanical is gonna get more fuel than it can suck....so I guess fuel will just get pushed through it???? I would have the electrical on the whole time...

I know I should just bypass it, im just trying to understand completely what is happenign, i want to learn.
Re: Can I run a Mechanical and Electric fuel pump together? [Re: Guitar Jones] #1299124
09/07/12 06:56 PM 09/07/12 06:56 PM
Joined: Oct 2003
Posts: 3,698
NE Oklahoma
V
Von Offline
master
Von  Offline
master
V

Joined: Oct 2003
Posts: 3,698
NE Oklahoma
I used to run an electric before the mech pump. Never had a problem. Many years ago I had a starvation issue. Put a red pump before the mech and never had a problem.

2 other buddys did the same thing with their sbcs.

A member on here has a red pump before his mech pump also. Never a problem also.

One thing to keep in mind if you put a blue pump before the mech pump you might have to put a reg after the mech pump. Im not sure on that??

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.
Re: Can I run a Mechanical and Electric fuel pump together? [Re: domingo] #1299125
09/07/12 07:01 PM 09/07/12 07:01 PM
Joined: Dec 2009
Posts: 20,640
in a cattle trailer down by th...
G
Guitar Jones Offline
Paddle faster! I hear banjo music!
Guitar Jones  Offline
Paddle faster! I hear banjo music!
G

Joined: Dec 2009
Posts: 20,640
in a cattle trailer down by th...
Quote:

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.



but the mechanical is gonna get more fuel than it can suck....so I guess fuel will just get pushed through it???? I would have the electrical on the whole time...

I know I should just bypass it, im just trying to understand completely what is happenign, i want to learn.



If the electric pump is on then it's not a problem, it's only a problem if you turned it off.

"Follow me the wise man said, but he walked behind"


'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. Rear disc and hydroboost conversion.
2019 1500 Long Horn Crew Cab 4WD, 5.7 Hemi.
Re: Can I run a Mechanical and Electric fuel pump together? [Re: Von] #1299126
09/07/12 07:07 PM 09/07/12 07:07 PM
Joined: Jan 2012
Posts: 1,650
Harm City Md.
Dan Halen Offline
top fuel
Dan Halen  Offline
top fuel

Joined: Jan 2012
Posts: 1,650
Harm City Md.
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.
Re: Can I run a Mechanical and Electric fuel pump together? [Re: domingo] #1299127
09/07/12 07:16 PM 09/07/12 07:16 PM
Joined: Aug 2007
Posts: 1,271
Vista, California
6
67Satty Offline
pro stock
67Satty  Offline
pro stock
6

Joined: Aug 2007
Posts: 1,271
Vista, California
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.
Re: Can I run a Mechanical and Electric fuel pump together? [Re: Guitar Jones] #1299128
09/07/12 07:23 PM 09/07/12 07:23 PM
Joined: Jan 2003
Posts: 403
southern Maryland
K
keefe Offline
mopar
keefe  Offline
mopar
K

Joined: Jan 2003
Posts: 403
southern Maryland
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.

1971 duster twister 440, 3380#,509 M/P hyd,906's,full Exhaust,11.06@117.46 1/4,6.95@ 97.03 1/8,1.497 60ft.....
Re: Can I run a Mechanical and Electric fuel pump together? [Re: 67Satty] #1299129
09/07/12 07:34 PM 09/07/12 07:34 PM
Joined: Jan 2003
Posts: 9,670
Lima, Peru
domingo Offline OP
EL Master
domingo  Offline OP
EL Master

Joined: Jan 2003
Posts: 9,670
Lima, Peru
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
Re: Can I run a Mechanical and Electric fuel pump together? [Re: keefe] #1299130
09/07/12 07:34 PM 09/07/12 07:34 PM
Joined: Jan 2003
Posts: 20,797
A collage of whims
topside Offline
Too Many Posts
topside  Offline
Too Many Posts

Joined: Jan 2003
Posts: 20,797
A collage of whims
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.
Re: Can I run a Mechanical and Electric fuel pump together? [Re: domingo] #1299131
09/07/12 07:38 PM 09/07/12 07:38 PM
Joined: Dec 2009
Posts: 20,640
in a cattle trailer down by th...
G
Guitar Jones Offline
Paddle faster! I hear banjo music!
Guitar Jones  Offline
Paddle faster! I hear banjo music!
G

Joined: Dec 2009
Posts: 20,640
in a cattle trailer down by th...
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.

"Follow me the wise man said, but he walked behind"


'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. Rear disc and hydroboost conversion.
2019 1500 Long Horn Crew Cab 4WD, 5.7 Hemi.
Re: Can I run a Mechanical and Electric fuel pump together? [Re: domingo] #1299132
09/07/12 09:55 PM 09/07/12 09:55 PM
Joined: Jun 2003
Posts: 14
Hickory Hills,Il
G
gonzo440 Offline
member
gonzo440  Offline
member
G

Joined: Jun 2003
Posts: 14
Hickory Hills,Il
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.
Re: Can I run a Mechanical and Electric fuel pump together? [Re: gonzo440] #1299133
09/07/12 10:29 PM 09/07/12 10:29 PM
Joined: Mar 2006
Posts: 2,675
Mt. Eden Ky.
Hemi Allstate Offline
master
Hemi Allstate  Offline
master

Joined: Mar 2006
Posts: 2,675
Mt. Eden Ky.
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.


1996 Ram 1500 Sport
1968 road runner
1952 Sears Allstate licensed, pump gas, Hemi 5.98 @ 115.73 1.33 60 ft. The best is yet to come. Painless Performance / Street RODDER magazine Top 100 for 2019
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