Anyone used PWM for pump between main fuel tank & swirl pot?

[JohnMcL]

I asked over on Home Mechanics but got no replies so maybe here is closer to potential user experience.

There are readily available PWM solutions for the pump from swirl pot to fuel rails. They use pressure sensors in the fuel lines and inlet manifold. But speed control for the low pressure pump from the main tank needs a level sensor in the swirl pot. Has anyone found, or could suggest, a commercially available combination of sensor/controller to do the job?

Thanks for any help.

[Storer]

I always thought that the low pressure pumps were self regulating.

If they detected a rise in pressure they shut down.

In our case where efi is used the high pressure pump is the one causing issues heating up the fuel.


Paul

[Steve_D]

Storer said:

I always thought that the low pressure pumps were self regulating.

If they detected a rise in pressure they shut down.

In our case where efi is used the high pressure pump is the one causing issues heating up the fuel.


Paul

The Carter pumps on my GTR are self regulating at about 6psi but do not shut down they just pressure relief in the pump but stay running.

Steve

[anonymous-user]

With a single pick up point and lift pump, there is no advantage (except a tiny power saving and a tiny noise saving) to be made by speed controlling your lift pump.

It should be run at full speed to quickly fill the swirl pot, and keep it full (ie to push out any air or vapour that has got there, to ensure the pressure pump always has a nice wet feed. Also, with a suitable restriction on the swirl pot return, the slight positive pressure in the swirl pot when the lift pump is at full speed helps to keep the pressure pump from cavitating at high flows.

If you have multiple lift pumps, in the corners of a wide shallow tank, then using a G sensor and only driving the pump that has the fuel sloshed towards it as you corner / brake etc can be advantageous if you really want to use ALL the fuel in the tank (ie for endurance racing etc)

[JohnMcL]

Thanks guys. Very helpful.

Its a Holley 12-801 with an internal relief valve at 7psi. There is a -6 overflow back to the main tank. The objective is to reduce noise, but taking Max Torque's comments I think I will just put a restriction in the return and let the pump run.

[Storer]

My in-tank l/p pump is virtually silent and I suspect Steve is right and it just dumps the fuel from a small relief valve when 6-7psi is exceeded.

I too have a small return from the swirl pot to the tank to maintain some pressure in the pot.


Paul

[Steve_D]

I have my return restricted to no more than a dripping tap as all you want to do is clear any trapped air/vapour which will clear through that restriction easily.

Steve

[Storer]

Mine is a 2mm hole......



Paul