2 inlets for my fuel pump???
Thread Starter
Cruising
Joined: Dec 2011
Posts: 10
Likes: 0
2 inlets for my fuel pump???
was attempting to install a new hi flow chrome holley fuel pump on my 78 when i noticed the stock pump has 2 seperate inlets. Why does this exist? there are actually 2 fuel lines running to the pump.
any help would be greatly appreciated guys.
Thanks!
any help would be greatly appreciated guys.
Thanks!
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
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Melting Slicks
Joined: Sep 2004
Posts: 3,223
Likes: 666
From: Northeast
Just a FYI. At the top of the forum there is something called "search this forum" where you can type in a part of the subject you are looking for. This has been discussed before:
http://forums.corvetteforum.com/c3-t...pump-help.html
You can find a fuel pump at any of the vendors listed in the column on the left. Think they are @ $35 however no bling.
http://forums.corvetteforum.com/c3-t...pump-help.html
You can find a fuel pump at any of the vendors listed in the column on the left. Think they are @ $35 however no bling.
Melting Slicks
Joined: Mar 2005
Posts: 2,838
Likes: 10
From: Austin TX
If your engine is turning some RPMs and making some HP, then you likely need an aftermarket fuel pump. Stock pumps flow around 30 GPH whereas a performance pump will flow 80 GPH or more.
The text from the book above is weak and I think they're confusing the return line with the vapor line (EVAP system) which vents the fuel tank with the use of the charcoal canister and vacuum from the induction system.
The return line from the pump is different, and shouldn't have any vapor in it. It's purpose is to loop fuel back to the tank to keep the fuel in the lines cooler to prevent vapor lock.
There are no performance fuel pumps, that I'm aware of, that employ a return line (as you're finding out). Your two options are to remove the return line and block the nipple at the fuel tank, or, as stated above, keep your stock fuel pump in play.
FWIW
The text from the book above is weak and I think they're confusing the return line with the vapor line (EVAP system) which vents the fuel tank with the use of the charcoal canister and vacuum from the induction system.
The return line from the pump is different, and shouldn't have any vapor in it. It's purpose is to loop fuel back to the tank to keep the fuel in the lines cooler to prevent vapor lock.
There are no performance fuel pumps, that I'm aware of, that employ a return line (as you're finding out). Your two options are to remove the return line and block the nipple at the fuel tank, or, as stated above, keep your stock fuel pump in play.
FWIW
Melting Slicks
Joined: Apr 2004
Posts: 2,008
Likes: 38
From: Space Coast Gator Territory
Without a return line supplied by a three port pump, you significantly increase the chance of developing vapor lock problems. Three port pumps are not as available as years ago. Ecklers and other vendors catering to older Corvettes still have them available. If you want to use your chrome two port pump, you might try placing a T in the line before the carburetor and feed fuel back through the return line. This way unused fuel will return to the tank and keep cool fuel under the hood. The early C-3 SB used a similar system, but with a nipple off a special fuel filter.
Last edited by Red 69; Dec 19, 2011 at 06:02 PM.
Safety Car
Joined: Oct 2005
Posts: 3,570
Likes: 1
From: Algonac Michigan
Yep...I was just given a 3-port pump the other day. It was a Carter. I sent it back and got the simple inlet/outlet pump I was replacing.
Nothing in the engine compartment is very original on my car though.
Nothing in the engine compartment is very original on my car though.
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
this is correct, and contrary to some popular beliefs....plus there is no drop in performance with the 41240 pump or advantage in performance with the 2 port for street engines.......go with the stock system, one less problem
Oh,
dump that 3.08 gear or just give up on performance
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 99
From: Ontario
this is correct, and contrary to some popular beliefs....plus there is no drop in performance with the 41240 pump or advantage in performance with the 2 port for street engines.......go with the stock system, one less problem
Oh,
dump that 3.08 gear or just give up on performance
Oh,
dump that 3.08 gear or just give up on performance
Thread Starter
Cruising
Joined: Dec 2011
Posts: 10
Likes: 0
THANKS for all your help gentlemen! Very helpful indeed
I forgot to mention that im running a 450hp-tunnel ram-4x2-semi radical cam setup. The reason for replacing my fuel pump is my pressure keeps bouncing around way too much as my 2nd fuel press gauge reads.
RED69:would placing the T after the pump and before my carbs rob pressure?
I forgot to mention that im running a 450hp-tunnel ram-4x2-semi radical cam setup. The reason for replacing my fuel pump is my pressure keeps bouncing around way too much as my 2nd fuel press gauge reads.
RED69:would placing the T after the pump and before my carbs rob pressure?
Pro
Joined: Aug 2010
Posts: 698
Likes: 8
From: Stockholm Sweden
If you want to use your chrome two port pump, you might try placing a T in the line before the carburetor and feed fuel back through the return line. This way unused fuel will return to the tank and keep cool fuel under the hood. The early C-3 SB used a similar system, but with a nipple off a special fuel filter.
As i see it (basic hydraulic) this will result in a flow back to the tank OK but the fuelpressure at the carb will be zero becouse the returnline now is open to tank.
//Ricky.
Melting Slicks
Joined: Apr 2004
Posts: 2,008
Likes: 38
From: Space Coast Gator Territory
THANKS for all your help gentlemen! Very helpful indeed
I forgot to mention that im running a 450hp-tunnel ram-4x2-semi radical cam setup. The reason for replacing my fuel pump is my pressure keeps bouncing around way too much as my 2nd fuel press gauge reads.
RED69:would placing the T after the pump and before my carbs rob pressure?
It would have been nice to know what your application was in your first question. Unless special application is specified, it is assumed it is a stock, or close to stock application. The main feed line is 3/8ths and the the return is 1/4, unless you changed that. A stock engine may have enough fuel pressure for short WOT runs with a 1/4 T off the main line, but that is moot at this point. If not, you could always put an inline fuel pressure regulator with a return port to assure ample pressure with your existing pump. Holley sells them for under $30. Either way, I would not run without a return because of vapor lock. I have been there and it can become a real PITA and usually happens at the worst possible time.