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Fuel Pressure Raised

beenowened

By beenowened,
in Engines & Forced Induction

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beenowened Enthusiast

beenowened

Posted
Posted

I recently put a walbro 450 e85 fuel pump in my 33 gtst, i hooked a fuel pressure gauge up after to check everything was still alright and found the pressure at vacuum was 3.5 bar. It has an adjustable regulator on it which looks similar to the nismo ones.

The car was tuned a few years ago at unigroup before i owned it with the basics pfc, 12psi, full exhaust, front mount, bosch 040.

With the pfc hand controller showing 88-90% duty cycle on the injectors at the top end.

So my question is, could the fuel pressure have been bumped up when it was being tuned or is the walbro flowing to much fuel for the reg to keep up with?

There has been a few thread saying it should be fine with it. Has anyone installed one and checked the pressure afterwards?

And will it be fine running at that pressure? will the current tune possible be affected if i do drop the pressure down or should i leave it how it is?

cheers

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Badgaz Experienced

Badgaz

Posted
Posted

more than likely they might've bumped up your rail pressure to try and get more out of your injectors...assuming they were stock. the pump can't over run the regulator. Yes the tune will be affected if you drop the pressure down....and yes you should leave it like it is until you upgrade your injectors....then change it back to 3bar.

vetter2769 Proficient

vetter2769

Posted
Posted

With such minimal mods (similar to me) then id say you'd be running stock fuel pressure.

This is how you set up for stock, and for your setup is identical to mine so this is what you need to do - take of the small hose vac/boost hose on the FPR, start car (it will idle lumpy) adjust the FPR till your gauge reads 43 psi (make sure the gauge is reading between the FPR and the rail, otherwise the FPR might have a port for a gauge, if so that will do fine)

once you've adjusted to 43 psi then re-attach the boost/vac hose and it should drop to around 34-38 psi and it will rise with the throttle/boost.

beenowened Enthusiast

beenowened

Posted
  • Author
Posted

more than likely they might've bumped up your rail pressure to try and get more out of your injectors...assuming they were stock. the pump can't over run the regulator. Yes the tune will be affected if you drop the pressure down....and yes you should leave it like it is until you upgrade your injectors....then change it back to 3bar.

Yeah thats what i assumed they had done i will leave it how it is for moment then. cheers

With such minimal mods (similar to me) then id say you'd be running stock fuel pressure.

This is how you set up for stock, and for your setup is identical to mine so this is what you need to do - take of the small hose vac/boost hose on the FPR, start car (it will idle lumpy) adjust the FPR till your gauge reads 43 psi (make sure the gauge is reading between the FPR and the rail, otherwise the FPR might have a port for a gauge, if so that will do fine)

once you've adjusted to 43 psi then re-attach the boost/vac hose and it should drop to around 34-38 psi and it will rise with the throttle/boost.

thanks mate i will do that when get my new injectors in soon.

vetter2769 Proficient

vetter2769

Posted
Posted

new injectors?

are they standard injectors because otherwise you will need a re-tune with the injectors in. you won't really be able to start you car, the pfc does has self learning modules, and you can tell the pfc that you've changed injectors etc.

Easiest thing to do would be have your tuner install the injectors.

unless you've got a trailer, if not hire one, install them yourself and take to tuners but don't start your car!

Badgaz Experienced

Badgaz

Posted
Posted

on any ECU when you are changing fueling parameters you need to adjust for this in the ECU. if he wants to put injectors in himself thats relatively easy and you can change the fuel injector correction calculation from the hand controller...this will allow him to drive the car to the tuner sedately where he can have a wideband and appropriate tuning equipment hooked up to retune.

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