2G 250lph vs. 450lph go big or go home?

[Kai Hefner]

I'm not too educated on fuel systems so bear with me here.

I'm going to be picking up some fuel parts from a friend. Now, my Talon doesn't have any engine management yet, but it will soon. I was wondering, what are the reasons to go a 250lph fuel pump instead of a 450lph? I understand the 250 is a common upgrade but are there any risks of me going to a higher flowing pump now? I want to avoid, in the future, my car running out of flow from the 250lph and having to upgrade to the 450lph.

I will be upgrading to braided fuel lines. I will have an AFPR. What are the risks, if any, of going to a higher flowing pump now rather than later?

 

[Vegas Smith]

It's very simple: if you're a real man, get the 450. If not, get the 255. Kidding, the only downside is on the 2gs there is some modding you have to do with the 450, otherwise, it's difficult to keep the pressure down.

 

[llxkevinxll]

https://www.dsmtuners.com/threads/2g-awd-fuel-siphon-mod.350851/

Just to be clear, what Vegas means about a mod for 2Gs is the fuel siphon needs to be opened slightly or you'll be unable to bring the rail pressure back down to nominal.

 

[Kai Hefner]

Seems really easy. One guy on that thread said he had a 255 drilled out to a 1/8", is 1/8" good enough for a 450?

 

[llxkevinxll]

Seems really easy. One guy on that thread said he had a 255 drilled out to a 1/8", is 1/8" good enough for a 450?

I ran a 255 with no modification. I just installed a 450 and a 7/64 hole was not good enough. The rail hung at about 52 psi with the car on and a rewired pump. You don't want to go more than 1/8" because you run the risk of the siphoning not working any longer, leaving half of your saddle tank filled with fuel that can't be reached.

 

[Kai Hefner]

I ran a 255 with no modification. I just installed a 450 and a 7/64 hole was not good enough. The rail hung at about 52 psi with the car on and a rewired pump. You don't want to go more than 1/8" because you run the risk of the siphoning not working any longer, leaving half of your saddle tank filled with fuel that can't be reached.

So I'm not sure what the fuel siphon does. When I do drill it out to size, is there anything I should be concerned about? Maybe look out for?

 

[llxkevinxll]

So I'm not sure what the fuel siphon does. When I do drill it out to size, is there anything I should be concerned about? Maybe look out for?

In the 2G awd cars the fuel tanks are shaped liked a saddle over the exhaust and drive shaft. That means that once the fuel level drops past the level of the middle of the saddle, one half of the tank is isolated from the fuel pump. The siphon is a small plastic orifice that the returning fuel is forced through. This is attached to the other half of the tank with one of the rubber hoses on the top of the hanger. The small plastic siphon is shaped such that the force of the passing fuel creates a vacuum on the rubber hose and it draws (siphons) fuel from the other half of the tank. If the siphon is damaged or or the orifice is made too large to create that vacuum, the fuel won't be sucked from the driver side of the tank. This means: 1. Your usable fuel capacity is halved. 2. Your fuel gauge will not read properly as the driver sending unit always sees full. Even when the passenger side is running out of fuel and the car no longer runs.

So, be careful not to break or damage the siphon when opening it up. I used a drill bit and just held it in my hand. It's 20+ years old and fuel soaked. It's soft enough to open by hand. And I wouldn't go larger than 1/8" as you may make it wider than the 450 pump can provide to ensure the suction action still works correctly.

 

[CORNF3DECLIPSE]

I went with the 450lph just so i could run a higher base fuel pressure to squeeze some extra juice from the injectors. But install was just as easy as a 255.