Diesel foaming when polisher on

[nfbr]

I have a problem with diesel foaming and bubbling up the vent pipe when the polisher is running / cycling fuel through.

Anyone seen this?

Thoughts on "defoaming"?

Thanks

[Pete7]

Is this just when the tank is close to full or at any tank level? Vetus do a widget for putting in the vent line. Its a little plastic moulded tank to allow the bubbles to disperse and the fuel to return to the tank.

Pete

[tkeithlu]

If I understand the process, basically multistep coarse to fine filtation, I'm left wondering where the air for the foam is coming from. Are you sucking air somewhere on the vacuum side of the pump?

[Uncle Bob]

Are you returning the fuel to the top of the tank or are you returning it through a tube to near the base of the tank.

[nfbr]

Originally Posted by Uncle Bob

Are you returning the fuel to the top of the tank or are you returning it through a tube to near the base of the tank.

Top of the tank, opposite end to pickup to promote end to end flow.
It's t'd into the vent fitting at the tank, which I suspect makes the issue worse.
Vent line is 1". Polish lines are 3/8". Pump is small 4psi pump, not large flow.

Air ingestion could be related - I need a section of clear line after the filter to check.

[Uncle Bob]

Originally Posted by nfbr

Top of the tank, opposite end to pickup to promote end to end flow.
It's t'd into the vent fitting at the tank, which I suspect makes the issue worse.
Vent line is 1". Polish lines are 3/8".

Install a tube to near the bottom and return the fuel through that, as far away from the pickup as practical. Fuel entering the tank to the top will foam when squirted in via a small diameter fitting. You may well be able to use the vent fitting for both with a little creative engineering.