Suby Club

Hi All

 

Can anyone brief me on how exactly the fuel pump priming works. I would assume it has either a pressure sensor or timer for the priming cutoff?

 

I've just got a long-standing issue where my pump keeps priming and doesn't cutoff at all. Obviously this is not an issue, as the regulator will keep bleeding excess fuel/pressure back into the tank, but it 'may' reduce the life of the regulator...? Its just bothering me when flashing the ecu, as the fuel pump keeps pumping away while the ignition is on, but again, not a big issue.

 

Anyone have a brief run-down on how the primer works before I start troubleshooting this? Or is there anyone who has had a similar issue?

 

Thanks
Josh

What engine?
2.5 or H6?

IIRC, the H6 has a fuel pump controller, but the 2.5 NA does not.
SO either the controller is stuck on or the relay is buggered and won;t shut off power to the pump.

Swap the relay first
Check the plugs under the rear seat and into the top of the tank that go to the pump.
May have a short keeping the pump running all the time

2.0 TT - no hate please

The fuel pump relay is the existing 2.5 relay though, which would mean it doesn't have a controller then. How does the 2.5 know when to stop priming then if it doesn't have a controller?

Out of interest it's been like this since the conversion. I'm just looking for some info on how the priming works or what differences there may be between models before I start pulling things apart to figure it out.

Thanks mate

It's just a 2 second timer. The ecu justs operates the fuel pump relay for 2 seconds at initial key on and obviously again once it detects engine speed. As rob suggested, could be the relay is shagged and stuck on.
It stays on with both the factory ecu and the eculabs?

Thanks. Yes it stays on with the factory GTB ecu and Eculabs. I may be able to adjust it in Eculabs, but I have a feeling that the way I have the outback rear loom plugged into the GTB front loom may have it 'hard wired' on. It might just be a matter of double-checking the pins on the connection or adjusting the settings in Eculabs.

If it has done it with both ecus than I would guess that it is most likely either the relay is stuck on or like you suggest, it is hard wired on from some funny wiring in the loom.
Probably easiest to just check or replace the relay first then double check your wiring. I wouldn't think this is something you can fix within the ecus settings.

Timer would be in the ECU,
But as the gen3 GTB would be designed to have the fuel pump controller connected, the timer would be integrated into the controller I'd suggest.
SO without it, the pump just runs all the time.

Won;t be a big issue.
Who did the conversion?

Also, just don;t leave the car on reds if you don;t have to

Car will run fine, it's just a bit of a safety issue.

Car gets crashed, splits fuel line etc.

 

Sound like the fuel pump controller may PWM the pump, like the H6 does.

Thanks guys.

I did the conversion.

So could I wire in a GTB/H6 fuel pump controller and be done with it? Where are the controllers usually located?

inside the LH Rear corner

Of the engine bay or car?

Car,
Near the fuel tank.

Don;t you have a Gen3 workshop manual?

I'll add a link

https://www.dropbox....2ad7/XVSUT4Wmta

Thanks mate. Yeah I do have the manual - lazy me!