Mechanical pump, or existing in-tank pump?

shnipplelicken · July 9th, 2007, 12:37 AM

ok, so heres whats up. I just did my first engine swap on my '90 stang. The V8 is from a '79 stang. My problem, or at least one of my problems, is that my car used to be EFI and the engine is carburated. My question is: can the mechanical pump still suck gas through the pump in the tank, even if the in-tank pump is disabled? Can I just use the in-tank pump to send fuel to the carb and just remove or bypass the mechanical pump? How should I go about doing this?

neverfastenough1 · July 9th, 2007, 06:55 AM

Definitely go with electric if possible. Reason being, mechanical pumps use hp to pump. You can use the in tank pump you have with a pressure regulator.

JBIGBOOTSY · July 9th, 2007, 09:28 AM

mallory makes a specific fuel pressure reg. for using the in-tank pump with a carb. You will not be able to pull fuel through the intank pump if you use the mech. pump.

neverfastenough1 · July 9th, 2007, 09:59 AM

Originally Posted by JBIGBOOTSY

mallory makes a specific fuel pressure reg. for using the in-tank pump with a carb. You will not be able to pull fuel through the intank pump if you use the mech. pump.

Yeah, you would have to pull the pump off and run a line from the pickup tube to the bottom of the tank. With a screen.

shnipplelicken · July 11th, 2007, 09:04 PM

ok, I guess its the electric pump FTW, but whats the exact regulator that I should use? Everything I've seen is between 30 and 60 psi. I was told that I should regulate the flow to about 6 or 7 psi to the carb. True?

JBIGBOOTSY · July 11th, 2007, 09:34 PM

mallory fuel pressure reg. part #4309

C MY 4D · July 11th, 2007, 10:21 PM

Yes electric pump FTW...... you need a 0-15psi regulator with a return bypass. I just got done converting my car over to carb and am still using my EFI BG Mighty Sumo pump. As long as the return line is large enough it will work great.

ryans88gt · July 12th, 2007, 12:47 AM

Yeah +1 on the return line.
I have a 140 gph out of tank electric pump designed for carbs with a 3/8" feed line. Originally I tried using the stock return line and the lowest I could get the fuel pressure down to was like 12 PSI. So I switched the routing around so that the factory feed line is my return line and this brought the pressure down to about 7-8 PSI. However, even with the 5/16" feed line as my return I can't turn the pressure down past 7-8 PSI...

With the factory EFI pump I could regulate between 3 PSI and 30 PSI using the factory feed and return line.

July 9th, 2007, 12:37 AM	#1
shnipplelicken Newbie Join Date: Jul 2007 Location: Hollywood, MD Posts: 4 iTrader: 0 reviews	Mechanical pump, or existing in-tank pump? ok, so heres whats up. I just did my first engine swap on my '90 stang. The V8 is from a '79 stang. My problem, or at least one of my problems, is that my car used to be EFI and the engine is carburated. My question is: can the mechanical pump still suck gas through the pump in the tank, even if the in-tank pump is disabled? Can I just use the in-tank pump to send fuel to the carb and just remove or bypass the mechanical pump? How should I go about doing this?

July 9th, 2007, 06:55 AM	#2
neverfastenough1 Hardcore Enthusiast 2002 Mustang GT Join Date: May 2007 Location: Savannah, Ga Posts: 2,778 iTrader: 3 reviews	Definitely go with electric if possible. Reason being, mechanical pumps use hp to pump. You can use the in tank pump you have with a pressure regulator. __________________

July 9th, 2007, 09:28 AM	#3
JBIGBOOTSY MM Fanatic 1990 LX hatch Join Date: Aug 2006 Location: Hobart Indiana Posts: 4,392 iTrader: 0 reviews	mallory makes a specific fuel pressure reg. for using the in-tank pump with a carb. You will not be able to pull fuel through the intank pump if you use the mech. pump. __________________ Bolt-on Abraham Lincoln Log motor. With extra wiring.

July 11th, 2007, 09:34 PM	#6
JBIGBOOTSY MM Fanatic 1990 LX hatch Join Date: Aug 2006 Location: Hobart Indiana Posts: 4,392 iTrader: 0 reviews	mallory fuel pressure reg. part #4309 __________________ Bolt-on Abraham Lincoln Log motor. With extra wiring.

July 11th, 2007, 10:21 PM	#7
C MY 4D Billy Weston 2003 Cobra 11.14@124.36 Join Date: Aug 2006 Location: Hampton, VA Posts: 4,794 iTrader: 7 reviews	Yes electric pump FTW...... you need a 0-15psi regulator with a return bypass. I just got done converting my car over to carb and am still using my EFI BG Mighty Sumo pump. As long as the return line is large enough it will work great. __________________ TT Build in progress....... Need work done to your car for a great price in Hampton Roads? Shoot me a PM.

July 11th, 2007, 09:04 PM	#5
shnipplelicken Newbie Join Date: Jul 2007 Location: Hollywood, MD Posts: 4 iTrader: 0 reviews	ok, I guess its the electric pump FTW, but whats the exact regulator that I should use? Everything I've seen is between 30 and 60 psi. I was told that I should regulate the flow to about 6 or 7 psi to the carb. True?

July 12th, 2007, 12:47 AM	#8
ryans88gt MM Fanatic Join Date: May 2007 Location: Bloomington, IL Posts: 4,627 iTrader: 0 reviews	Yeah +1 on the return line. I have a 140 gph out of tank electric pump designed for carbs with a 3/8" feed line. Originally I tried using the stock return line and the lowest I could get the fuel pressure down to was like 12 PSI. So I switched the routing around so that the factory feed line is my return line and this brought the pressure down to about 7-8 PSI. However, even with the 5/16" feed line as my return I can't turn the pressure down past 7-8 PSI... With the factory EFI pump I could regulate between 3 PSI and 30 PSI using the factory feed and return line. __________________ 88 GT CHI headed 351w 10.8 @ 125 - still figuring it out. 03 Cobra 2.3 whipple 10.7 @ 129 - sold it 04 Mach 1 12.7 @ 109 mostly stock - sold it 89 LX procharged 302 515 hp 497 ftlbs 10.7 @130 mph - sold it

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