I think Edelbrock suggest 6.5 psi max, Mikes 4-5psi sounds spot on.
71 ls5 fuel pressure
Thread Starter
Pro
Joined: Nov 2008
Posts: 680
Likes: 5
From: Denham Springs LA
71 ls5 fuel pressure
I have a 71 LS5, 454 365 hp with 58,000 miles.
How much fuel pressure should it have at the carb? I measure 7 to 9 psig. I am currently replacing the fuel tank and fuel pump due to heavy rust in the tank. Worried I will still have this problem after I install these parts.
I have had 3 different carbs on this car and all of them had problems with dripping gas into intake, either while idling, or when the engine is turned off.
When I bought the car a couple months ago it had been sitting for several years, only being cranked occasionlly. it had a rebuilt quadrajet that flooded continuously.
I replaced the carb with a new Edelbrock just to drive it home. After driving for a few hundred miles it too begin flooding at idle and when the engine was turned off. I cleaned the needle valve and replaced fuel filter. flooding stopped mostly.
I recently purchased the correct quadrajet, had it rebuilt, and installed it. Ran it for about 15 minutes and when I shut the engine off the primary's were dripping gas into intake.
Any advice will be greatly appreciated.
Thanks
Roger
How much fuel pressure should it have at the carb? I measure 7 to 9 psig. I am currently replacing the fuel tank and fuel pump due to heavy rust in the tank. Worried I will still have this problem after I install these parts.
I have had 3 different carbs on this car and all of them had problems with dripping gas into intake, either while idling, or when the engine is turned off.
When I bought the car a couple months ago it had been sitting for several years, only being cranked occasionlly. it had a rebuilt quadrajet that flooded continuously.
I replaced the carb with a new Edelbrock just to drive it home. After driving for a few hundred miles it too begin flooding at idle and when the engine was turned off. I cleaned the needle valve and replaced fuel filter. flooding stopped mostly.
I recently purchased the correct quadrajet, had it rebuilt, and installed it. Ran it for about 15 minutes and when I shut the engine off the primary's were dripping gas into intake.
Any advice will be greatly appreciated.
Thanks
Roger
Thread Starter
Pro
Joined: Nov 2008
Posts: 680
Likes: 5
From: Denham Springs LA
The fuel pump on the car Has 3 ports and looks stock. I just bought a new stock 3 port fuel pump I will install this week. Hoping that lowers the fuel pressure.
When I dropped the tank the rubber return line was sort of kinked. I corrected it and have my fingers crossed that my fuel problems are solved.
When I dropped the tank the rubber return line was sort of kinked. I corrected it and have my fingers crossed that my fuel problems are solved.
Race Director
Joined: Dec 2004
Posts: 15,025
Likes: 2
We always flow checked the carbs we remanufactured @10-12psi. They can handle it, but not as a rule. As Mike and Golden said, 4-6psi is the recommended pressure.
You said you had tank rust issues. When you have rust or other contaminate problems, they never just stay in the tank. When you clean and or replace the tank, you need to perform the same to the entire fuel system. Fuel lines, return lines, filters and fuel pumps need to be serviced, or you are just going to pump the crap right back into the carburetor. An inline filter will help, but will soon become clogged if the appropriate measures aren't taken to clean the entire system.
You said you had tank rust issues. When you have rust or other contaminate problems, they never just stay in the tank. When you clean and or replace the tank, you need to perform the same to the entire fuel system. Fuel lines, return lines, filters and fuel pumps need to be serviced, or you are just going to pump the crap right back into the carburetor. An inline filter will help, but will soon become clogged if the appropriate measures aren't taken to clean the entire system.
Race Director
Joined: Nov 2002
Posts: 12,142
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From: Taylor Michigan
Replacing the fuel tank will probably fix the issue...Good possibility that the needle and seat was clogged with a piece of rust...9 is too high, but 7 is normally the high figure for all mechanical pumps. But you mentioned that the new carb worked under the same conditions. But dirt and rust coulld get into the new carb also....
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