Issue: Fuel line Pulsating with Walbro Intank

[Bazda]

Short story - Installed a Walbro intank pump to my car and the main fuel line pulsates, the pump also sounds a little strange like not a nice continuous wining noise, sounds more like a rolling of ball bearings (but much quitier).

The pump is installed into a large 3L surgetank, another pump from the main tank feeds the surge tank. Fuel rail returns back into the surge tank and an over flow back down to the main tank. And yes the surge tank is full as I have a level indicator on it.
Basically the same setup as i've always run but I used to have a Bosch 044 off the surge tank, decided it was too noisy so is why i've made the change.

Anyone heard of this pulsating issue before?? sounds to me like a dud walbro pump. Car seems to drive fine and boosts fine. Just not happy with the strange things its doing...

[strx7]

walbros flow shite, why did you go there?
there flow rating is at 45psi where bosche etc flowrates are at 70 psi or so

[Bazda]

walbros flow shite, why did you go there?
there flow rating is at 45psi where bosche etc flowrates are at 70 psi or so

I used to run one with 330kw with no issues. But changed to the bosch setup as went for a surgetank, but bosch was way too loud so chanigng back to a walbro but put that inside the surge tank.

Anyhow i've got a Aeromotive intank to try out next week. After I do some trouble shooting tonight.

[Quint]

sounds more like a rolling of ball bearings

Sounds like cavitation.

edit add. the pressure at the intake of the pump is dropping below its NPSH requirement (if it is cavitation). try mounting it lower to get a bit more head pressure on it and see if you get a change. Pump should have an NPSH value supplied in its literature, easy to work out what is being supplied to see if the requirements are met.

note: pressure is a function of height not volume.

[Bazda]

The pump is inside a surge tank, its mounted at the bottom of the surge tank.

I cant mount the pump any lower, I cant mount the surge tank any lower either.

[Quint]

One way would be to have the pump mounted out of the surge tank and lower and have it fed from the surge tank, probably not practical considering it's an intank pump...

Does the surge tank go under atmospheric pressure? (is it able to breath freely)

[Bazda]

There is no breather as such on the surge tank.

The lines running to the tank are -
1. Feed from the main fuel tank via another 255lph pump
2. Over flow off the top of the surge tank to the main tank
3. Return from the fuel tail to the surge tank
4. Outlet from the inside walbro pump to the fuel rail

And yes the pump needs to be mounted inside the surge tank as thats what its designed to do. I already ran the external 044 but its damn loud.

I'll have a check tonight again. I only saw it pulsing on first start up, possibly air lock. I drove it 40km last night and it seemed to drive as it normally would.

[Mr Ree]

Where was the walbro bought from? Any chance of it being a clone?

[Bazda]

After some more testing I think its ok. The pulsating is gone now. Must of been air trapped. But sound of the pump is not as id expect it to sound, possibly because its in a alloy tank, getting another pump to try anyhow.