fuel pump question
Thread Starter
Pro
Joined: Jun 2005
Posts: 703
Likes: 153
From: Central FL
St. Jude Donor '06 thru'17, '23-'26
fuel pump question
Is the fuel pump gravity fed from the tank? If I disconnect the "S" rubber line at the tank hardline/rubber line interface, should fuel "pour" out or just "trickle" out?
Thanks
Car is a '76
Thanks
Car is a '76
Team Owner
Joined: Sep 2006
Posts: 31,301
Likes: 4,389
From: Westminster Maryland
Hi T,
Since the sending unit is in the top of the tank on your 76 I'd think it would be more of a trickle…. just the gas in the line.
On earlier tanks on which the sending unit is in the bottom of the tank, gravity does force the gas out the fuel line.
Regards,
Alan
Since the sending unit is in the top of the tank on your 76 I'd think it would be more of a trickle…. just the gas in the line.
On earlier tanks on which the sending unit is in the bottom of the tank, gravity does force the gas out the fuel line.
Regards,
Alan
Last edited by Alan 71; Feb 14, 2017 at 07:45 AM.
Thread Starter
Pro
Joined: Jun 2005
Posts: 703
Likes: 153
From: Central FL
St. Jude Donor '06 thru'17, '23-'26
Hmmm, I'm getting nothing, and when I hook a vacuum pump and start to siphon, I'm only getting a trickle. Car hasn't started in 8 years, I'm trying to determine if it's the fuel pump or maybe the screen in the tank that may be clogged or the supply line. I'm not getting any fuel anywhere in the system even after I siphoned fuel to the pump and reattach the 's' tube to the supply line and the crank the engine. Nothing to the carb, filter, pump discharge, pump suction. After your post I'm leaning to a clogged screen in the tank.....
Melting Slicks
Joined: May 2012
Posts: 2,192
Likes: 344
From: Allenton Wisconsin
I'd suspect the tank sock filter is at with fault, even though the sender is on top once the siphon action has started the fuel should just keep on coming. Mechanical fuel pumps pump, they don't have much suction to them. T
Le Mans Master
Joined: May 2002
Posts: 5,086
Likes: 787
From: Lebanon Township New Jersey
Hmmm, I'm getting nothing, and when I hook a vacuum pump and start to siphon, I'm only getting a trickle. Car hasn't started in 8 years, I'm trying to determine if it's the fuel pump or maybe the screen in the tank that may be clogged or the supply line. I'm not getting any fuel anywhere in the system even after I siphoned fuel to the pump and reattach the 's' tube to the supply line and the crank the engine. Nothing to the carb, filter, pump discharge, pump suction. After your post I'm leaning to a clogged screen in the tank.....
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Team Owner
Joined: Jan 2006
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From: Crossville TN
Have you removed the vapor recovery tank? THAT is the vent for the fuel tank. If it is removed, you need to install a vented gas cap so that tank pressure can equalize.
What happens to the fuel flow (with your "S" tube test) if you remove the gas cap???
What happens to the fuel flow (with your "S" tube test) if you remove the gas cap???
Thread Starter
Pro
Joined: Jun 2005
Posts: 703
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From: Central FL
St. Jude Donor '06 thru'17, '23-'26
Thank you! That was it, just turned the ignition and within 2 or 3 seconds had fuel in the bowls and fired right up. Thanks everyone for your input and help!
4th Gear
Joined: Jun 2016
Posts: 4
Likes: 0
1973 vented gas cap
I’m looking for a vented gas cap for my 1973 Corvette. can I use a vented gas cap from a 68 to 69 vett. I was about to replace my fuel pump when I started going through some of your threats and realize that my tanks vent line was plugged. Because someone before me removed the vent tank up front. At the time it didn’t dawn on me I’d be creating a vacuum after I accelerated. When I put the peddle to the metal the car would die out like it was running out of gas. I thought the fuel pump was bad. Since I already replaced the fuel tank, rebuild the carburetor, blew out the fuel lines and rebuilt the carburetor, replaced all the filters. I figured the only thing left was the fuel pump. Wrong!... lol