Fuel pump return line.

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Mr. Monte
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Joined:Wed Apr 09, 2008 12:38 pm
Location:Minnesota
Fuel pump return line.

Postby Mr. Monte » Sun Jul 27, 2008 10:46 am

hi guys, after melting a few elctrodes on the plugs at the last race using some NOS, I realized it's time to add an additional fuel pump. I run a Mallory 140 and I am adding a seond one, one pump will be dedicated to the motor and one pump with a toggle switch will be turned on when I run the nitrious.
I have a lot of fuel line as well as a return line. here is my question : The return line is the same diameter as my fuel line, I have been told that the return must be larger than the fuel line. How crucial is that and can I get away with using the line I have rather than purchasing larger line ?
Nobody wins alone. Jimmy

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rock
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Location:Des Moines, Iowa

Postby rock » Sun Jul 27, 2008 2:00 pm

Are you adding a second Mallory 140 pump? If so i don't remember it having a return on the pump.Or are you returning the fuel from the regulator? Here is a link to fuel system setup and the returns are not bigger than the feed line http://www.productengr.com/mm5/pumpinst ... nguide.htm

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Eric David Bru
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Postby Eric David Bru » Sun Jul 27, 2008 4:27 pm

I see no reason to have the return line larger than the feed line.

EDB
Outlaw Eric :cool:

Mr. Monte
Posts:19
Joined:Wed Apr 09, 2008 12:38 pm
Location:Minnesota

Postby Mr. Monte » Mon Jul 28, 2008 8:55 am

Hi Rock and Eric, thanks for getting back to me. Here's what I have :
The motor makes 609 h.p. on the dyno and the NOS kit is at 250 h.p. which I hardly use. But at the track I have my fuel pressure set at 7-8 and by the 1000 ft. mark its dropping to ONLY 1 !! I currently run a mallory 140 ( dead-headed) no return line. We just added the second Mallory 140 yesterday and will finish plumbing the line today. I wasnt sure if it was o.k. to run both pumps to the regulator then to the carb and NOS plate with or without running a return line. Lots of my friends run dual 140's without a return line, I thought a return line would keep the fuel cooler.
Nobody wins alone. Jimmy

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rock
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Location:Des Moines, Iowa

Postby rock » Mon Jul 28, 2008 11:39 am

i would run the second pump just to the nitrous system with its own regulator
make sure when you set the fuel pressure for the nitrous it is flowing

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Eric David Bru
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Postby Eric David Bru » Mon Jul 28, 2008 8:11 pm

Yep, what Rock said... /\

EDB
Outlaw Eric :cool:

Mr. Monte
Posts:19
Joined:Wed Apr 09, 2008 12:38 pm
Location:Minnesota

Postby Mr. Monte » Tue Jul 29, 2008 9:40 am

o.k. thanks guys, appreciate it.
Nobody wins alone. Jimmy


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