4 bar fuel pump question?

[LuckyvRS20vT]

Need a 4 bar fuel pump for my vRS... was offered a pump from Audi TT but these are twin tank so I didn't get it

 

So the question..... 

 

Do I need a pump from Leon cupra R, are these single tank pumps?? 

[Mankee]

Strange. Just this evening I was talking to the chap who I bought a BBT actuator and BAM injectors from about fuel pumps.

 

The 4WD pumps need one of the ports blocking up like you say. So the only other choice is Leon Cupra R. But do you trust a used pump with probably unknown history? I don't. Plus there's numerous threads saying that Leon Cupra AUQ pumps are 4 bar anyway. Bit of a minefield.

 

So this unit from Motorsport Tools is straight fit apparently and filthy cheap:

 

http://www.motorsport-tools.com/sytec-hi-in-tank-fuel-injection-pump-36mm-in-8mm-out-p30311.html

 

What are your signs of a weak pump? And do you have a 4-bar regulator to go with the pump? I'm sticking with a 3-bar reg with 380cc injectors and just want the pump to provide consistent fuel delivery.

[LuckyvRS20vT]

No I'm sticking with 3 bar reg so the pressure stays right in the rail... otherwise fitting a 4 bar will overfuel and the ecu will see this and hold back in other areas...

So by fitting a 4 bar pump, that will keep the pressure up to the ref, then the ref will do its job from the rail..

 

Symptoms are, since the map, if I try to floor it the car holds back... yet if I build the throttle up and wind the boost up it goes like the clappers.. been told try new filter, fitted fuel filter and stayed the same.. So I'm going to fit this 4 bar pump I just payed for.. It's out of a Leon cupra R and he said its 4 bar so all good..

[David 8]

Put it this way, your older pump may be okay when wound up gradually, put when your asking for all out powah it may be a little tired.

 

Your injector duty cycle was high the other night which could well be a sign that OE pump is struggling a bit.

[mannyo]

Does the fuel pump not run at a constant speed, it does in my Audi. The fuel which is not needed by the injectors is pumped back to the fuel tank by the same pump. So the pump in effect always runs at a speed to supply sufficient fuel for full throttle, returning unused fuel back to the tank.

[David 8]

Could well do, you're right in saying that it returns the unused back to the tank.

 

So thats my theory up the swannie lol

[LuckyvRS20vT]

Not really... as a fuel pump can start to fail and not provide enough fuel up top ect. And once completely broken... car won't run at all 

[Gonzaga]

Does the fuel pump not run at a constant speed, it does in my Audi. The fuel which is not needed by the injectors is pumped back to the fuel tank by the same pump. So the pump in effect always runs at a speed to supply sufficient fuel for full throttle, returning unused fuel back to the tank.

 

It would run at the same speed (flow) if the pressure is constant which isn`t  , pressure in the fuel rail is. When the pressure rises fuel flow drops and vice verse. 

Edited 13 February, 2014 by Gonzaga

[Mankee]

Not really... as a fuel pump can start to fail and not provide enough fuel up top ect. And once completely broken... car won't run at all 

This is exactly what happened to the pump in my Caterham. Was fine mid-range but went lean at the very top as the pump couldn't meet the demands of the rail pressure. It made no difference if we added more injector duty or upped the pressure, the AFR didn't change. New pump fixed all that. Hopefully it'll fix your latest problem as well.

[LuckyvRS20vT]

I hope so mate.. we will see Tuesday if the weather is nice