Fuel Pump Load V RPM

[8krpm]

I'm trying to wire in a Walbro 460 in an evo 8MR (3 plug ECU).

The car is running a Link G4X, just wondering what ways we could wire it in so that we could have it behave on a load vs RPM basis.

My usual go to is to just hardwire it to the battery via a relay and bulkheads, but recently a friend who went with an EMtron had his wired via an EVO fan controller which is able to adjust voltage variably to the pump and have it run only the voltage it needs for the load it sees.

I'm OK at wiring - just not savvy with putting together components that work together to make it work and was wondering if the Link G4X plug in ECU could operate in a similar way using an available input which could then be configured through PC Link, sort of like a GP Output on an ignition drive but with more parameters to control the pump in a more OEM fashion.

Cheers in advance, sorry if parts of this post don't make a lot of sense.

[Adamw]

The ECU has many options for controlling the pump depending on what hardware you go for.  Your car should already have a two speed fuel pump control in it from factory.  So provided it is not causing you large voltage drop at high pressures I wouldn't bother changing.  The reason for varying pump speed is generally to reduce noise at idle/cruise and give full pump speed at higher load.  The low/high switch point is user adjustable.  There are other options in the software such as 3 speed PWM and fully configurable open loop PWM as well. 

To do variable speed PWM control you will need a solidstate relay, a pump controller, or a fan controller like your mate.  The problem with the fan controllers is they are designed to fail "active" (ie fan on all the time) rather than fail off for safety which the fuel pump controllers are generally designed to so I would consider that before going that way.  The Evo fan controllers are well known for failing.  There is a ford fuel pump controller that some use but it is only good for about 20A from memory.

But be aware you wont really gain much compared to your existing system - maybe a slightly more smooth pressure transition from low speed to high speed but thats about all.  The "pump heating the fuel" is really just an old myth if thats what you are thinking, there may be a little heating with extreme fuel systems with 3 high pressure pumps or something, but I certainly see no fuel heating in my car with a walbro 450 in it.  From memory I got a couple of degress after an hour or so of pump running.  The fuel heating actually mostly comes from the metal fuel rail that is attached to the hot cylinder head and slowing the pump down doesnt change that one bit.   Even my injector flow bench which only holds 5L of fuel only gets luke warm after a few hours of testing.  

 

[8krpm]

3 hours ago, Adamw said:

The ECU has many options for controlling the pump depending on what hardware you go for.  Your car should already have a two speed fuel pump control in it from factory.  So provided it is not causing you large voltage drop at high pressures I wouldn't bother changing.  The reason for varying pump speed is generally to reduce noise at idle/cruise and give full pump speed at higher load.  The low/high switch point is user adjustable.  There are other options in the software such as 3 speed PWM and fully configurable open loop PWM as well. 

To do variable speed PWM control you will need a solidstate relay, a pump controller, or a fan controller like your mate.  The problem with the fan controllers is they are designed to fail "active" (ie fan on all the time) rather than fail off for safety which the fuel pump controllers are generally designed to so I would consider that before going that way.  The Evo fan controllers are well known for failing.  There is a ford fuel pump controller that some use but it is only good for about 20A from memory.

But be aware you wont really gain much compared to your existing system - maybe a slightly more smooth pressure transition from low speed to high speed but thats about all.  The "pump heating the fuel" is really just an old myth if thats what you are thinking, there may be a little heating with extreme fuel systems with 3 high pressure pumps or something, but I certainly see no fuel heating in my car with a walbro 450 in it.  From memory I got a couple of degress after an hour or so of pump running.  The fuel heating actually mostly comes from the metal fuel rail that is attached to the hot cylinder head and slowing the pump down doesnt change that one bit.   Even my injector flow bench which only holds 5L of fuel only gets luke warm after a few hours of testing.  

 

Hi Adam,

Thank you for your really well written and considerate reply.

The main reason I was going for the two speed style was as you mentioned for the overheating (or overruning the pump if supplied max voltage 100% of the time) I've been reading about. In my previous evo I ran a 255 lift pump and two 350 pumps in the surge, all hard wired, and didn't have issues (no data to back this up, only right foot of course). This time around I thought as a second attempt at a build I'd try and do it "properly", but in the scheme of things the overheating issue seems to be negligible gauging by your response and my own experience (I wasn't really aware of the overheating phenomenon at all during my first build).

In that case I will hardwire it with a solid state relay as I usually would.