You need to put a couple of notches in the pump housing to clear 2 short nubs on the walbro. DON"T CUT THE NUBS OFF!!!

I cut them off and my pump worked for about a month. then one day pump lost all pressure because of my mod to the pump. I disassembled the pump, and a found a cap and a spring that cam out of where I cut the nubs off!

I just reinstalled a new walbro (Thanks to Sharif for the quick overnight service!!!) but this time I broke out the dremel and I made 2 small notches in the housing to clear the nubs. The nubs are located on the output side of the pump!

 

I can verify the fuel starvation issue! I installed a Walbro fuel pump about 3 weeks ago because the stock fuel pump wasn't supplying enough fuel while cranking over. The Z would refuse to start unless I let it sit for a couple minutes, then the pump would provide enough fuel. I never had any issues after the car was started. To install the walbro pump, I followed turbonetics instructions, including drilling two rather large holes in the surge tank. I plan on spraying upwards of 150 shot with an NX wet kit in the future, and I didn't want the fuel soleniod to be starved of fuel, especially at wide open throttle. Nitrous - enough fuel = BOOM. After installing the fuel pump, I drove the car for a couple days until a was on E. While sitting at a light, I started hearing "slurping" coming from behind the passenger seat. Sure enough it kept getting louder and louder. I try to keep it above an 1/8th of a tank or so now. I will be installing a fuel pressure gauge when I install the nitrous kit and a-pillar gauge pod to see if the fuel pressure is where it should be at.

QuadCam - What's the perfect place for the fuel pressure to be, and what's a dangerous level, low and hi?

After I installed my headers I got dynoed and had a SUPER lean a/f curve. I was running high 14's in some places across the board. After installing the fuel pump, I noticed the car A)started alot easier every time and B)had a deeper exhaust note. There seems to be an increase in torque under 3krpm on top of the header gain, and the car pulls hard to redline.

If any of you guys are planning on putting a walbro in the Z, DON'T DRILL OUT THE SURGE TANK!

-Acree

 

Hmm I have a fuel pressure gauge and haven't seen any drop in fuel pressure when I get to below 1/5 of a tank. But I try my best to stay out of boost when I am that low on gas. Something about being low on gas and doing full boost runs that doesn't make sense to me. As for fuel pressure I see 53-55 PSI at idle.

 

if anyone ever needs fuel system technical support, please feel free to PM me here. We have done tons of R&D with the 350z and G35 fuel systems, and I think we are the only ones who setup true return conversions for the sedens. I have worked on them and tried more things than probably anyone, so its somewhat of a hobby of mine.

 

this is absolutely correct. there is no gained function by putting holes in the surge tank.. but there is loss of a swirl pot function and surge tank function by doing this. a true surge can has absolutely no openings near or at the bottom... and if it does, its not functional. a surge tank should always be completed sealed at the bottom, with the only place for fuel to escape as out the top.

 

Phunk,, for clarification, are you recommending to not modify the pump (Walbro/drilling holes) as the TN install manual say;'s??

 

The regulator probably needs to be modified as instructed to keep fuel pressure correct. But I wouldnt punch any holes in the can. Also, I would not remove the yellow swirl jet on the outside of the can, but the pinhole orifice on it does need to be opened up to about .068 - .070 to support the larger pump.

 

Whoops. I guess I need to go find that and open my assemlby back up.

Phunk - Can you recommend any fix for the surge tank other than buying a new one? Anything I can do to "patch" the holes permanently?

-Acree

 

you could make a square shaped patch out of aluminum and rivet it on there and use JBWeld as a bit of sealant for the patch.... ghetto fo sho, but its all I can think of.

A new assembly at Nissan is about $250 including pump and level sensor and etc.

I will have a surge can that I can give away for dirt cheap pretty soon that is left over from our twin fuel pump R&D.

 

Awesome! PM Sent.

-Acree

 

Would you use a surge tank with twin Walbro's? (i.e. APS twin pump setup)

 

do u have a pix of what u are referrring?

 

A good flowing fuel system with a single Walbro 255 will flow well over 600rwhp on a Dynojet 248... in comparison the typical APS fuel system that is in their turbo kits maxes out at around 500 rwhp on a Dynojet. These are not speculation, as these numbers have been tested and proven.

To add a second pump creates a ton of absolutely unnesessary ammount of fuel flow under 99.5% of driving conditions. The insane ammount of fuel that is being pumped out merely to recirculate back into the tank creates high levels of evaporative emissions and puts unnesessary heat in the gasoline.

One solution is to put the second pump on a switch that activates it at a prescribed boost level. Unfortunatly, this is an unsafe practice as you are relying on additional components. If that switch or wiring failed, you would find out about the same time your engine cracks a piston.

Our factory surge tank design is phenomenal. We have here, a standalone and unbaffled pump assembly with integrated surge tank, swirl pot, and venturi siphon that can contain fuel well enough to run our engines at VERY high HP full throttle at very low tank levels (comparitively).

You have to be not thinking to throw away this amazing OEM unit until your cars HP just is not quenchable with a single fuel pump.

That said, if my car was making the HP to out-run a well designed single fuel pump setup (which it will soon), I would definatly utilize a twin pump in-tank surge can. However, I would not consider the APS twin pump setup a surge can. An employee of APS posted to a thread on another forum telling me that their can has opening on the bottom of it to allow the pumps to get fuel when the tank level is lower then the walls of their can. This officially disqualifies it as a surge can, and the can might as well not even be there, as it surves no purpose. This system will undoubtably have the same symptons I predicted that the instructed modifications to the OEM can by Turbonetics would have, which were later confirmed by a few owners of the setup. Around a 1/4 tank, they have fuel starvation problems as the fuel gets away from the pumps... because they were instructed to punch hole(s) in the surge can, officially eliminating its function.

aalzuhair, we have been testing a true in-tank surge can setup with larger displacement and greater functionality. We learned a few different tricks and methods for designing extremely high flowing in-tank surge cans from the engineers at Mercedes. Maybe in about 4 more weeks or even less now, we will show you some proven OEM techniques to keeping an actual surge can full to the top under extremely high flow demands.

 

At this moment on this computer I do not. If you have any pictures of your pump assembly that you would want to post, i would gladly draw on to demonstrate.

 

Phunk I sent a PM. Please let me know about that extra surge can as soon as you possibly can. I almost ran out of gas today on a 3hour road trip even though the tank showed a lil under 1/4.

-Acree

 

acree: I got your PM, sorry i didnt reply I figured I would just reply when I was ready to ship it. We will probably be done using it for final measurements this week. There is something we are trying to get just right, and its nice to have the stock unit for reference.

 

Sounds great. Hopefully I will be installing a fuel pressure gauge in the near future so I can monitor pressure.

Can anyone list off some recommended steps if my pressure is too high? How do you acurately lower it to within the stock range? Something to do with the regulator I'm sure. I drilled out the stock regulator 1 bit size smaller than Turbonetics recommended.

-Acree

 

there are other factors involved then the regulator. once the regulator flow sufficiently, the internal return flow is still restricted by 2 venturis. one of them is accessable, and that is the yellow one on the outside of the can that turbonetics tells you to remove. if you enlarge the pinhole oriface to about .070 it wil be able to flow enough to keep pressure where it needs to be... but i highly reommend a fuel pressure gauge, even if its just a mini $20 in the engine bay.

 

i was reading the aam fuel return line and it doesnt have anything on drilling out the surge tanks. Why would u need to? Is it to just drop the pressure?

I have another question. I'm planning on staying around ~380hp but I want to ditch the fmu/ inline pump on my vortech. I understand the aam fuel return line is the best solution but is it really needed for lo hp? I was wanting to do stock rails with 440cc + walbro and to have it controlled with the greddy EU. Will this setup work well or will it be risky? Also, if I dont get the return line, I would have to drill a small hole in the surge tank?

 

Putting a Walbro in my G Sedan very soon and wanted to revisit a few things to be sure the info in this thread is still correct for a Walbro with out a return system in a G Sedan.

1) No need to drill the factory regulator?
2) Cut notches in the housing rather than clip off the tabs on the pump?
3) Enlarge the pin hole oriface on the yellow part on the outside of the surge can to .070

Is this the right things to do for a Walbro install on a G Sedan?