'84 Vette fuel pump
Le Mans Master
Joined: Sep 2000
Posts: 6,303
Likes: 714
From: Bartlett IL
Re: '84 Vette fuel pump (shadypete)
Shady,
Why would you need 60psi for a Xfire? Although you may be running larger TB's are you using larger injectors? I am using 80# injectors and I have an LT-1 pump in my tank. FP is set at 10.5psi and I am running 13.6 in the 1/4 with about 275hp at the wheels. Larger TB's don't automatically require more psi. Have you looked at burning a new chip?
What other mods have you done?
Why would you need 60psi for a Xfire? Although you may be running larger TB's are you using larger injectors? I am using 80# injectors and I have an LT-1 pump in my tank. FP is set at 10.5psi and I am running 13.6 in the 1/4 with about 275hp at the wheels. Larger TB's don't automatically require more psi. Have you looked at burning a new chip?
What other mods have you done?
Race Director
Joined: Aug 2002
Posts: 13,356
Likes: 0
From: tucson AZ
St. Jude Donor '04 & '05
Re: '84 Vette fuel pump (shadypete)
shadypete,
did you check out installing the '85 fuel pump??????
If you do install let me know...how you did it?????
thanks
tony
:cool:
did you check out installing the '85 fuel pump??????
If you do install let me know...how you did it?????
thanks
tony
:cool:
Le Mans Master
Joined: Jan 2002
Posts: 7,460
Likes: 5
From: Burnet, TX
Re: '84 Vette fuel pump (oldace84)
shadypete,
did you check out installing the '85 fuel pump??????
If you do install let me know...how you did it?????
thanks
tony
:cool:
did you check out installing the '85 fuel pump??????
If you do install let me know...how you did it?????
thanks
tony
:cool:
It's fairly simple... it took about 25 minutes. On the crossfire injection vault they have a FAQ section that will describe with pictures how to do it.
:cheers:
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Re: '84 Vette fuel pump (shadypete)
A word to the wise. The later pumps WILL put out more pressure than the stock '84 pump. The question is: do you need more pressure? My Crossfire has 2" throttle bodies and a VERY ported manifold. My fuel pressure is set to 14 lbs. As a test, I made a time trial run at the strip with a fuel pressure guage taped to the outside of the windshield. Even with winding my engine beyond 6000 rpms, the needle never even wiggled. It stayed steady, at 14 lbs, through out the whole run. If the pump weren't able to supply the needed volume of fuel, the pressure would have dropped. It would be a shame to replace a failed '84 pump with a "stock" pump. It would be a bigger shame to waste money on a later pump if it isn't needed. IF the stock pump is doing it's job, a bigger, better, later, pump will provide NO benefit.
RACE ON!!!
PS. The pump upgrade is a "no brainer". It is a direct fit, with only minor wiring connections to be made.
RACE ON!!!
PS. The pump upgrade is a "no brainer". It is a direct fit, with only minor wiring connections to be made.
Le Mans Master
Joined: Sep 2000
Posts: 6,303
Likes: 714
From: Bartlett IL
Re: '84 Vette fuel pump (CFI-EFI)
CFI,
If you really need to run 14psi for best performance I would look into using a VAFPR to raise FP when you need it at WOT. I would suggest 14psi isn't necessary constantly. Also look into tuning your bin file. Pumping up the FP usually indicates a band-aid approach to the real fix which is modifying your fuel map. :yesnod: :chevy
If you really need to run 14psi for best performance I would look into using a VAFPR to raise FP when you need it at WOT. I would suggest 14psi isn't necessary constantly. Also look into tuning your bin file. Pumping up the FP usually indicates a band-aid approach to the real fix which is modifying your fuel map. :yesnod: :chevy
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Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Re: '84 Vette fuel pump (Dominic Sorresso)
Dominic,
They're lots of things I could or should do. Like a new timing chain (145,000++ miles). I have since cut the pressure back to 13#. I probably could reduce it further. Even at 14# it didn't seem to run rich, still got better than 22 mpg, average, AND passed the smog test. I agree, 14# SHOULDN'T be needed for everyday driving. I don't have the equipment to read or adjust the .bin files. Can that even be done with a stock ECU and prom?
By the way, why do you have an LT1 pump for 10.5 pounds of fuel pressure?
RACE ON!!!
[Modified by CFI-EFI, 1:20 PM 11/29/2002]
They're lots of things I could or should do. Like a new timing chain (145,000++ miles). I have since cut the pressure back to 13#. I probably could reduce it further. Even at 14# it didn't seem to run rich, still got better than 22 mpg, average, AND passed the smog test. I agree, 14# SHOULDN'T be needed for everyday driving. I don't have the equipment to read or adjust the .bin files. Can that even be done with a stock ECU and prom?
By the way, why do you have an LT1 pump for 10.5 pounds of fuel pressure?
RACE ON!!!
[Modified by CFI-EFI, 1:20 PM 11/29/2002]
Le Mans Master
Joined: Sep 2000
Posts: 6,303
Likes: 714
From: Bartlett IL
Re: '84 Vette fuel pump (CFI-EFI)
Dominic,
They're lots of things I could or should do. Like a new timing chain (145,000++ miles). I have since cut the pressure back to 13#. I probably could reduce it further. Even at 14# it didn't seem to run rich, and still got better than 22 mpg, average. I agree, 14# SHOULDN'T be needed for everyday driving. I don't have the equipment to read or adjust the .bin files. Can that even be done with a stock ECU and prom?
Actually Matt on the CFI forum was doing a hack of the stock ECM so that you could make mods. IMO, the 7747 has been meticulously documented and there's plenty of "freeware" available making the stock ECM hack redundant. But the answer to your question is yes.
By the way, why do you have an LT1 pump for 10.5 pounds of fuel pressure?
Two reasons:
1. My TB's are now plumbed in parallel. So its important that the same pressure be applied to both simultaneously. Although the stock pump can put out over 13psi, it doesn't have much reserve beyond that, making consistent pressure delivery "iffy".
2. I have found the LT-1 pump to provide "rock-steady" pressure while the stock pump fluctuated. I am running an external regulator also and there's more fuel line to keep up to pressure. Again, I was looking for something that has more "reserve" capacity. The stock pump is pretty stretched by that point.
RACE ON!!!
[Modified by CFI-EFI, 1:10 PM 11/29/2002]
They're lots of things I could or should do. Like a new timing chain (145,000++ miles). I have since cut the pressure back to 13#. I probably could reduce it further. Even at 14# it didn't seem to run rich, and still got better than 22 mpg, average. I agree, 14# SHOULDN'T be needed for everyday driving. I don't have the equipment to read or adjust the .bin files. Can that even be done with a stock ECU and prom?
Actually Matt on the CFI forum was doing a hack of the stock ECM so that you could make mods. IMO, the 7747 has been meticulously documented and there's plenty of "freeware" available making the stock ECM hack redundant. But the answer to your question is yes.
By the way, why do you have an LT1 pump for 10.5 pounds of fuel pressure?
Two reasons:
1. My TB's are now plumbed in parallel. So its important that the same pressure be applied to both simultaneously. Although the stock pump can put out over 13psi, it doesn't have much reserve beyond that, making consistent pressure delivery "iffy".
2. I have found the LT-1 pump to provide "rock-steady" pressure while the stock pump fluctuated. I am running an external regulator also and there's more fuel line to keep up to pressure. Again, I was looking for something that has more "reserve" capacity. The stock pump is pretty stretched by that point.
RACE ON!!!
[Modified by CFI-EFI, 1:10 PM 11/29/2002]
Thread Starter
6th Gear
Joined: Nov 2002
Posts: 6
Likes: 0
From: Scottsdale AZ
Re: '84 Vette fuel pump (oldace84)
I installed an LT-1 pump which is almost a direct change. BIG thing is the wire connecter to the pump. Chev doesn't have one.
The stock pump would drop ~2psi under full throttle. new pump is rock steady. its the way to go.
The stock pump would drop ~2psi under full throttle. new pump is rock steady. its the way to go.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Re: '84 Vette fuel pump (shadypete)
The stock pump would drop ~2psi under full throttle. new pump is rock steady. its the way to go.
RACE ON!!!
