Carb in tank fuel pump???
#1
Member
Thread Starter
Carb in tank fuel pump???
Hi, I have the 87 formula with the CC Rochester carb on a 305 engine. Supposedly there is a low pressure pump in the fuel tank to keep the line to the engine pump pressurized to eliminate vapor lock.
I have a fuel pump relay on the firewall but don't know if I have the pump or if i its working. I cant find a bit of information on it. I have never heard it, yet the car runs perfectly.
Does anyone have any information on this mystery pump?
Thanks,
Louis
I have a fuel pump relay on the firewall but don't know if I have the pump or if i its working. I cant find a bit of information on it. I have never heard it, yet the car runs perfectly.
Does anyone have any information on this mystery pump?
Thanks,
Louis
#3
Supreme Member
iTrader: (7)
Join Date: May 2004
Location: Lexington, SC
Posts: 5,291
Likes: 0
Received 58 Likes
on
52 Posts
Car: 1987 SC/1985 TA
Engine: 350/vortec/fitech
Transmission: T56
Axle/Gears: 3.27 9-bolt
Re: Carb in tank fuel pump???
jump the hot and power to pump leads on the relay connector and you should note fuel flowing from the supply line...you can disconnect it and drop it in a container.
the car will run with a failed in-tank pump, the block pump will just have to pull through the dead one in the tank. It will be more susceptible to fuel starvation under high demand and vapor lock than a system with pick up only in the tank. best to keep it functioning.
I put a pressure gage on mine once and it didn't read much if anything, although it did flow fuel. could have been a worn pump or just the nature of things.
the car will run with a failed in-tank pump, the block pump will just have to pull through the dead one in the tank. It will be more susceptible to fuel starvation under high demand and vapor lock than a system with pick up only in the tank. best to keep it functioning.
I put a pressure gage on mine once and it didn't read much if anything, although it did flow fuel. could have been a worn pump or just the nature of things.
#4
Member
Thread Starter
Re: Carb in tank fuel pump???
Thanks Drew and Naf. This is good info.
Louis
Louis
#5
Junior Member
Join Date: Apr 2015
Location: massachusetts
Posts: 58
Likes: 0
Received 0 Likes
on
0 Posts
Car: 96 Impala 84 berlinetta
Engine: LT1
Transmission: 4speed auto
Axle/Gears: 3.23
Re: Carb in tank fuel pump???
vapor lock is when the carb gets too hot . I never had any vapor lock issues. fuel manual pump on the block does fail and it will reduce power. 305 CU is not a engine that requires high fuel volume . a 350CU with power up grades will .
if I had an power problem I would hook up the fuel pressure gauge .. 7 psi ish ..fuel filter dirty also ..check engine vacuum should be 17 inches and higher at 600rpm's..
if I had an power problem I would hook up the fuel pressure gauge .. 7 psi ish ..fuel filter dirty also ..check engine vacuum should be 17 inches and higher at 600rpm's..
#6
Senior Member
Join Date: Apr 2016
Location: Perth Western Australia
Posts: 517
Likes: 0
Received 4 Likes
on
3 Posts
Car: 1987 Z28 Camaro
Engine: 305 LG4 4bbl
Transmission: TH700R4
Re: Carb in tank fuel pump???
the issue isnt the carb getting hot, its the fuel lines that run next to the exhaust/headers getting hot. For the first start of the day, turn the key to run (not start) and listen, youll probably hear a whirrrr coming from the back of the car for a few seconds as it primes.
If no whirr, it either doesnt exist, or its dead. but if theres no issue with how the car is running, then theres no need worry about it. Theyre a tiny little low pressure pump, i think the one i replaced my dead one with was about 4psi from memory.
If no whirr, it either doesnt exist, or its dead. but if theres no issue with how the car is running, then theres no need worry about it. Theyre a tiny little low pressure pump, i think the one i replaced my dead one with was about 4psi from memory.
#7
Junior Member
Join Date: Apr 2015
Location: massachusetts
Posts: 58
Likes: 0
Received 0 Likes
on
0 Posts
Car: 96 Impala 84 berlinetta
Engine: LT1
Transmission: 4speed auto
Axle/Gears: 3.23
Re: Carb in tank fuel pump???
insulate the fuel lines and perhaps the headers .. see if that works do it on the cheap then use some high quality high temp insulation ..
Trending Topics
#8
Supreme Member
iTrader: (4)
Re: Carb in tank fuel pump???
From everything I read on the in-tank pusher pumps, they're only pushing 2-3psi tops, just enough to keep the fuel flowing "forward" and keep it circulating to help prevent the vapor lock issues when the lines are hot. When I did my original 350 swap, I got rid of it and ran a whalboro with regulator up in the engine bay.
#9
Supreme Member
iTrader: (4)
Join Date: Oct 1999
Location: GO PACK GO
Posts: 4,211
Likes: 0
Received 2 Likes
on
2 Posts
Car: 83Z28 HO
Engine: Magnacharged Dart Little M 408
Transmission: G Force 5 speed
Axle/Gears: Moser 9" w/Detroit Trutrac
Re: Carb in tank fuel pump???
I'm guessing this was only added to cars that were sold in hot climate areas. That being said, the fuel lines do come seriously close to the passenger side exhaust....just a bad design altogether really. When I bought Edelcrock TES headers years ago, they came with a fiberglass "wrap" to cover the fuel lines in that area, which helped. I never had vapor lock issues myself....maybe just lucky.
Thread
Thread Starter
Forum
Replies
Last Post
Justin Hertel
LSX and LTX Parts
6
10-23-2018 01:52 PM
whytspeeddevil
Electronics
2
03-18-2003 04:02 PM
un4givin89
Tech / General Engine
1
10-06-2001 04:20 PM