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SU Fuel Pump Running Continuously

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R

RonR

Jedi Trainee
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Folks.

I have a SU Electronic fuel pump on my Healey 3000. The pump is around 20 years old.
Recently, the fuel pump has failed to shut off when the engine is running.
I replaced the needles and seats in the float bowels, and that helped, but did not completely solve the issue.

Is it possible that the expensive SU electronic fuel pump has an internal failure, in that it no longer senses when the fuel lines are pressurized?

Thanks.
Ron
 
Ron,

It's the pressure in the fuel line between the pump and the carbs that keeps the pump from running on. If there's a leak at the carbs, in the fuel line or internal to the pump (outlet valve), then the pump will continue to run. It's a strictly mechanical valve. SU pumps are rebuildable.
 
"Recently, the fuel pump has failed to shut off when the engine is running."

Am I missing something here? If the engine is running then the pump won't shut off.

Danny
 
So many pump complaints, I am getting tired of them. Just get a low pressure Facet that looks like a ignition coil. They have been around since WW2. Cut the banjos off or get a little Moss kit that keeps them.
 
Hangtown Healey said:
So many pump complaints, I am getting tired of them. Just get a low pressure Facet that looks like a ignition coil. They have been around since WW2. Cut the banjos off or get a little Moss kit that keeps them.
Click to expand...
The gold rectangular Facet pumps will run continuously. Don't know abut the round version.
 
RonR said:
Folks.

I have a SU Electronic fuel pump on my Healey 3000. The pump is around 20 years old.
Recently, the fuel pump has failed to shut off when the engine is running.
I replaced the needles and seats in the float bowels, and that helped, but did not completely solve the issue.

Is it possible that the expensive SU electronic fuel pump has an internal failure, in that it no longer senses when the fuel lines are pressurized?

Thanks.
Ron
Click to expand...
The SU fuel pump "senses" the lines are pressurized by not being able to overcome the pressure. You may have a leak downstream of the pump, an air leak between the tank and the pump, or a leak in the pump check valve. A leak in the check valve may be a problem with valve itself, or a piece of grit in the valve. Start with looking of a leak downstream, then a leak between the tank and pump. If you don't find the leak in either of those places, then move on to the pump. It's best to start with the easiest and cheapest things first, then move to the harder stuff.
 
Disconnect the fuel line going to the carbs and with a small container immerse the fuel line in the container with a little bit of gas. Power on the pump and look for bubbles in the gas. If you have bubbles, you have an air leak. Simple test!
 
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