ARMAN

Hi im having alot of trouble with my fuel system i cant get it to prime if anybody knows which relay is responsible for priming the engine can u please let me know, Is it the main fuel relay or the (speed) relay that primes the motor, and how long does it prime for before it flicks off? Thanks to everyone for the info... I hope i get this going ..

weetbix13

have you tried priming it through the diagnosis box?

ARMAN

yeah but i wanna get to the bottom of it because there is a short circut somewhere and i cant find it my car is not responding to the ecu for low rpm fuel pump voltage it should drop but stays at 12V, i need to know which relay is responsibel for priming the motor because somewhere along the wiring of that relay is the short.

weetbix13

why do you think it should drop voltage?
shouldn't the fuel pump constantly recieve 12v to pressurise the fuel rail? the injectors should pulse voltage to allow fuel into the chambers, but the pump itself should be 12v right?

does the fuel pump even interact with the ECU?

ARMAN

Ahh for sure it does in the standard twin turbo setup the motor recieves 8.8V in low range rpm and 12.2V for higher rpm, thats 8.8V with the resistor at the right temp, the Ecu is the switch, as the revs get higher it flicks over to 12V thats when the Fuel relay (Speed) should kick in and complete the circut, but when you start your car the car starts in 12.2V untill the correct temp is reached then the relay should switch to 8.8V which will be open. im pretty sure that the Fuel (speed) relay is responsible for priming the engine and combined with the fuel resitor provide the correct voltage to the pump. Thats my theory as myne is Fu*ked but my engine doesnt even prime, and i have fault codes along that relay's wiring.. Thats why i wanted to know if thas the case, because no auto elec can figure it out. 2 of them thought my car is supposed to have an airflow meter lol i didnt even bother with them, and they were supposed to be "The best for fuel problems". who knows...

weetbix13

well i'll be damned... you learn something new everyday!
hit the sticky at the top of the forum, you'll probably need the wiring diagram to figure it out... trace the wires back from the EGI fuse (in the box closest to the diagnosis box).

can you give a full account of the symptoms? rough idle, high idle... rich condition etc?

ARMAN

yeah i been working on it all day cant find the problem...
Symptoms...

Burning too rich u can really smell it! stinks out the road u can smell it 6 cars back at the lights.

Lots of farting and small backfiring from excess fuel leaking into the exhaust.
Louder backfiring when down gearing as the revs drop also due to extra fuel in the exhaust.
80Ltrs of petrol for 200km's lol half of it pours into the exhaust. lol
smoke from unburned petrol in the exhaust.
Fuel cut off, i think the sensors are sending the wrong info to the ecu, mayb creating overboost but my second turbo isnt even kicking in.
This all comes down to the fuel i know that now because

I hooked up a 6V batter to my fuel pump started the car idles like a dream and revs out perfectly throtle is responsive didnt choke or stutter up till 3500RPM thats when the relay should kick in and take over 12.2V but obviously not because i had a 6V batter hooked up to it. weird **** i need someone with a fd to compare the process of the fuel system thats the only way i rekon i can find the fault and get to the bottom of it i made a diagram see if u understand it.

ARMAN

RED= Positive
ORANGE=FUSES
BLACK=Groud
LIGHT BLUE= Wire to ecu which should flick the Voltage to the pump.
YELLOW= Fuel Pump
SKY BLUE= Relays in the system.
LIGHT GREEN= RELAY RESISTOR
DARK GREEN= + for the relays from fuse box. 12.2V
DARK BLUE= Cant figure them out. Mayb just wires connecting components to complete circut.

ARMAN

Where abouts in NZ are you from in from Auckland.

weetbix13

manukau way... plenty of FD's here!
i had no idea about the changing voltage... that may help me source my fuel smell