So I was wondering how many of you have fuel starvation problems. I am starting to see it more and more the faster I get. In every case it is on right handers, typically long sweeping ones. When I was at VIR in October, I was getting it coming onto the front straight. The car is heavily loaded onto the left side coming onto the straight. If I left the paddock with less then 3/4 tank, I would get fuel cut and that is only in a 15 minute TT session. I know the Spec Z guys are having this issue too. The few that I talked to at VIR in October were experiencing the same thing in the same location on the track.

There is a thread on the NASA forum about adding a secondary fuel pump to try to fix this problem. They have not tested it, but it sounds like it would work. It seems that the drivers side tank is the one that would need it because I believe the fuel pump is on the passenger side. I am wanting to get this starvation issue under control so I can run less fuel to save weight. Fuel is really heavy and if I could run it down to almost empty, I could save a lot of weight.

Anyone have any ideas? I was thinking of adding another OEM pump to the drivers tank and tying the lines together. Not sure if a pressure adjustment would be needed or if that would even work. I would rather not get a fuel cell at this time either.

 

You can always use a secondary surge tank...

 

What exactly is that? I've never heard of that before.z

EDIT: I used the power of the internet and looked. Something like this:

http://www.radiumauto.com/Fuel-Surge...umps-P272.aspx

 

The problem with a surge tank is needing to add a fuel return... cjmotorsports makes an in-tank kit (designed for the z34 but should work in a z33) that feeds the stock pump. Probably both cost about the same IIRC.

 

I was just looking into the surge tank a bit and did notice that a return line would be needed. The CJ kit I thought was just a bigger pump for FI guys?

EDIT: I see what you're talking about. I see the road race pump they make for the 370. The description describes my issue exactly and that it fixes that.

 

Build an external surge or buy the radium version would be easiest IMO. I have all the parts for an external, I just need to assemble. I don't think you need the one CJM adapter since you are not really bypassing the internal reg, you are still not using it, but you are not converting to a return system.

 

Dont say the faster you get the more you realize it. Thats scares me since im getting a decent amount faster now

 

That CJ pump is $1000. Wow! The surge seems a much cheaper way to go, just more work involved.

 

You need a swirl pot.

 

For the spec z solution. What would prevent the second fuel pump from overfilling the other side of the tank? I would think it would need a return back to itself.

 

Saddle tank, does not matter. It will flow back over when filled or all flow back over when you take a rt hand corner.

 

I thought converting to a return style system was pretty expensive too... It's been a year or two since I looked into it though. The 370 will starve about a half a session in depending on the track.

 

adding a surge tank isnt that easy for our cars.

normaly in a surge tank setup the regulator return goes to the surge tank and the surge tank return goes to the oem sending unit.

But this will result in a pressurized surge can. The source of the pressure will be the restrictive plumbing for the siphons in the OEM sending unit. If you drill the swirl jet too large, to try and lower this pressure, the siphons will then not work... then your problem will be even worse

and it means a pressurised container full of fuel, (not very safe)

my solution was to not worry about the siphon from the other side, i only needed 35-45L capactity so i just cut the tank in half to save weight.



that way i can drill out the siphons so it doesnt pressurise the swirl pot (surge tank)

EDIT: yes thats the left side of the tank, my car is RHD so i wanted to move tank and pumps to other side of car for balance

 

I thought about cutting the tank in half as well, but I am not sure if it will hold enough fuel for a race. With your cut in half tank setup, can you run it completely empty?

 

You can the cjm kit on stock pump! The the kits directions it says "if running an aftermarket pump you need ti enlarge the swirl jet in the sending unit" I just installed the cjm stage 1 in my car very easy to do and Charles at cjm is awesome to talk and deal with!!!!

 

as you can see i cut it a fair bit less than half and including the fuel filler pipe etc it holds about 40L.
as for being able to run it low, ill hopefully be able to test that this weekend.
up untill now ive ran it 3/4 full for a coupld of short tests.
but i cant see why i shouldnt be able to.

FYI when i was removing the old tank it was showing 1/4 left in it, which measured out to be 36L.
so even running a full tank now weights less than the old setup with it showing 1/4.

i guess to proof will be how much of the 40L is useable

 

Why not simply add a transfer pump on the driver side to pump fuel over to the OEM fuel pump? I have done this in (2) 370Z with no issues after adding the pump. There is a siphon/crossover tube already on the driver side that goes directly to the OEM fuel pump assembly, find a place to mount a low pressure pump (I used a Chevy TBI fuel pump), use 1' of submersible fuel line and attached the output of the pump directly to the crossover tube so it is always feeding the OEM fuel pump. For power I added a relay that is triggered off the factory fuel pump, drilled then threaded bolts through the plastic hat with ring terminals/washers, and you could add a toggle swith on relay ground if you wanted to but I just wired it to run anytime the OEM fuel pump was running. Works like a champ and we have maybe $100 in it. Its not my idea, a 370Z racer told me how he did it so I copied his idea and it works just fine.

 

I was reading that is what a couple of the Spec Z guys did. I think I am going to go that route. It's definitely the cheapest and easiest.

 

so far ive run it down to 15L left and had no issue, hopefully this saturday ill be able to run it down more to see when it runs out.

the idea of adding a pump is a good idea to help the starvation issue. i removed half the tank mainly for weight saving, it just happened to be a solution to the starvation issue too.

 

Do you have any pics to see how to do this?