plymouth67
Well-Known Member
The one I put on looks like this.
Last edited:
Fuel Pump Slowly Dies
- Thread starter Doorkicker
- Start date
RedlineRed
New Member
Very interesting post Doorkicker. I am having a very similar problem with my slant 6 in a 73 Valiant (yes this is an A body but very similar problem).
Background:
Recently had engine rebuilt and dyno tested. Ran great but fuel supply was from an electric pump and pressure was never measured.
Car had been sitting for many years so a new fuel tank was installed with new gaskets, cleaned up sending unit, and new filter sock. Lines blown out with brakleen until it ran clean. New in line fuel filter. New ethanol free fuel. Old fuel pump.
Had a carb flooding problem so I installed a fuel pressure gauge to verify pressure. About 6psi. Another carb solved the problem. But I noticed that my fuel pressure slowly dropped to 0 after about 30 minutes of idling. After about 10 minutes of idling, you can hear the fuel pump starting to struggle to pump (it makes a mid level pitched, low volume level popping noise).
Short test drives (under 5 miles) do not have any noticable performance issues. Hesitating on going for longer drives.
Trouble shooting:
Replaced pump as the old one was very old. New pump is Carter, made in Mexico. Slightly higher pressure but still drops to near 0 after about 30 minutes of idling. Same struggling noise from fuel pump.
Opened fuel tank cap to see if there would be an inrush of air (maybe the emission vent line was plugged). No change in fuel pressure, no inrush of air.
The steel fuel line on this slant 6 is original and comes in from the right front side of the engine, under the alternator, up and over the water pump and runs close to the number one exhaust manifold outlet. So, I thought I might be getting some vapor lock.
Disconneted fuel line and put it back on the bottle to verify no hose connection leakage.
Did temperature readings every 5 minutes on the fuel line where it crosses over exhaust manifold.
Started at 84F and after 30 minutes ended at 123F.
Check fuel pressure every 5 minutes as well. Started at about 6.75psi, after 30 minutes down to about 0.5psi.
As the fuel pump started to struggle I notice that small bubbles were starting to come from the end of the fuel pickup hose at the bottom of the clear 2 liter coke bottle. Bubbles increased until the bottle was nearly empty.
I have not had time to pursue remedies. I was going to try to insulate the steel fuel line where it crosses over the exhaust manifold.
You may want to try the 2 liter coke bottle to see if you have the bubbles. I am not yet sure why I have this but am convinced it is a symptom of the problem.
Background:
Recently had engine rebuilt and dyno tested. Ran great but fuel supply was from an electric pump and pressure was never measured.
Car had been sitting for many years so a new fuel tank was installed with new gaskets, cleaned up sending unit, and new filter sock. Lines blown out with brakleen until it ran clean. New in line fuel filter. New ethanol free fuel. Old fuel pump.
Had a carb flooding problem so I installed a fuel pressure gauge to verify pressure. About 6psi. Another carb solved the problem. But I noticed that my fuel pressure slowly dropped to 0 after about 30 minutes of idling. After about 10 minutes of idling, you can hear the fuel pump starting to struggle to pump (it makes a mid level pitched, low volume level popping noise).
Short test drives (under 5 miles) do not have any noticable performance issues. Hesitating on going for longer drives.
Trouble shooting:
Replaced pump as the old one was very old. New pump is Carter, made in Mexico. Slightly higher pressure but still drops to near 0 after about 30 minutes of idling. Same struggling noise from fuel pump.
Opened fuel tank cap to see if there would be an inrush of air (maybe the emission vent line was plugged). No change in fuel pressure, no inrush of air.
The steel fuel line on this slant 6 is original and comes in from the right front side of the engine, under the alternator, up and over the water pump and runs close to the number one exhaust manifold outlet. So, I thought I might be getting some vapor lock.
Disconneted fuel line and put it back on the bottle to verify no hose connection leakage.
Did temperature readings every 5 minutes on the fuel line where it crosses over exhaust manifold.
Started at 84F and after 30 minutes ended at 123F.
Check fuel pressure every 5 minutes as well. Started at about 6.75psi, after 30 minutes down to about 0.5psi.
As the fuel pump started to struggle I notice that small bubbles were starting to come from the end of the fuel pickup hose at the bottom of the clear 2 liter coke bottle. Bubbles increased until the bottle was nearly empty.
I have not had time to pursue remedies. I was going to try to insulate the steel fuel line where it crosses over the exhaust manifold.
You may want to try the 2 liter coke bottle to see if you have the bubbles. I am not yet sure why I have this but am convinced it is a symptom of the problem.
Curiousyellow71
Well-Known Member
Is the fuel gauge fluid filled and under the hood? If it is the heat can affect it. It will read lower then actual, often showing zero. Something to try is resetting the gauge if it is a fluid filled unit. It won't fix your fuel problem but verify if the gauge is reading correctly.
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