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...

[MWP]

Is it a genuine pump?
Is the power supply to it up to scratch?
Could it be the FPR?

[Bazda]

FPR is the same as i've run for years, power supply is the same supply I used for the Bosch 044.

Basically all I have done is swap the bosch 044 surge tank setup out for a Walbro surge tank setup (put the walbro inside the surgetank). Everything else is the same. When I bought the walbro they said it was genuine and they had quite a few for sale, seems like no one had issues with them. I have bought another pump any how and its on the way so will also try this.

Possibly the surge tank needs to breathe? maybe a 1-way valve so it can suck air in. I'll pop the top open tonight and dis-connect the main feed and see what noises the walbro makes.

[2004lowlux]

would have thought a pulsation dampner off say a vl might help. the bosch pump may have had an internal bypass so it wasnt noticable where as the walbro possibly wouldnt so as the injectors cycle the fuel flow is stop/starting causing pulsation.
spose the best way to find that out is let the fuel cycle through the system with the injectors disconnected or not cycling and if the main fuel line isnt pulsating then theres your answer.
well thats my two cents anyway hope it helps.

[Bazda]

Yea I will try out a few things tonight.

[oldcorollas]

does fuel rail have the normal damper on it?
does the pump have a filter on it, and if not, how far from the bottom of the tank is it.. could be cavitating?

[Bazda]

Fuel rail there is none, its the stock 20v ITBs internal fuel rail it runs through.
Yes has the filter on the end and its sitting right at the bottom of the surge tank.

I just checked it now, its not pulsating any more :S. I think there must have been an air lock in the system when I first primmed the system. But it still makes a strange sound, not like a fuel pump sound to me. I will investigate more after dinner!

Hold 45psi at idle fine as well.

[thechuckster]

45psi at idle is a bit high? at 26psi boost, the thing would be pushing ~80psi?

[Bazda]

Yes its 45psi and has been like that since 2007.
Therefore goes up to 75psi with 30psi of boost, but I normally run 27psi at the drags.
My FPR can handle this any how.

The recommended pressure should be around 43psi by most peoples standards.

The Bosch 044 is good for 800hp with 45psi base pressure and 30psi of boost to get an a/f of approx 11.5:1
I changed to the intank walbro which for this same level would be good for 517hp.

But now i'm only going to be running 22psi max and a smaller turbo, therefore less power but alot more mid range i'm looking for this time round. Only wanted to hit 300kw max power atw as i only use the car for circuit racing .

Oh turned on the pump last night and it wasnt pulsating, thats with the car off. Didnt have time to start it and check, will do that tonight but been talking to a few guys in NZ with 044s and they get this issue when the car is idling or the fuel is quite warm.

Most likely would need a pulsating damper on the fuel rail.