Erattic fuel pressure - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

the head · 05-23-2005, 10:14 AM

I have a 98 blacktop S13 SR running a JGS fuel rail 560cc top feed injectors, walboro 255 pump, and a nismo adjustable FPR i have it set to 44psi but when it warms up or under load i am not getting consistant pressure i have sen it drop as low as 12 about 5 lbs of boost at full throttle when running and it seems to fluctuate between 20 and 35 psi during light throttle and idle not sure what is up with it

btw I am using a new 300zx fuel filter and it is controlled by a haltech ecu

orion::S14 · 05-23-2005, 01:44 PM

Do you have the OEM wiring goig to the pump, or a seperate circuit with new relay? S13 wiring is known to be insufficient for bigger pumps.

If it's just stock wiring...run a new ciurcuit to the fuel pump.

Use the stock fuel pump + wire to turn a relay on and provide a dedicated circuit just for the pump.

See KA-T.org for a S14 install...S13 is almost identical:

http://www.ka-t.org/tech - "Rewiring Your Walbro 255 Pump for S14's"

Do that, report back with results...

the head · 05-23-2005, 01:52 PM

Good thought I will just hotwire the pump 10 ga sould be sufficent for the power wire right?

RBS14 · 05-23-2005, 02:57 PM

don't hotwire it, a relay cost's like $4.

the head · 05-23-2005, 04:06 PM

That is how it is referred to where i am from if you are mainlining power to the pump we call it hotwiring with or without the relay

I am using a relay

RBS14 · 05-23-2005, 05:01 PM

oh ok, cool.

05-23-2005, 10:14 AM	#1
the head Nissanaholic! Join Date: Jul 2002 Location: in a dark room mastering the art of typing with one hand Posts: 2,164 Trader Rating: (3) Feedback Score: 3 reviews	Erattic fuel pressure I have a 98 blacktop S13 SR running a JGS fuel rail 560cc top feed injectors, walboro 255 pump, and a nismo adjustable FPR i have it set to 44psi but when it warms up or under load i am not getting consistant pressure i have sen it drop as low as 12 about 5 lbs of boost at full throttle when running and it seems to fluctuate between 20 and 35 psi during light throttle and idle not sure what is up with it btw I am using a new 300zx fuel filter and it is controlled by a haltech ecu __________________ I never knew you could do that with an eggplant

05-23-2005, 01:44 PM	#2
orion::S14 Nissanaholic! Join Date: May 2003 Location: Orange Park, FL Posts: 1,665 Trader Rating: (0) Feedback Score: 0 reviews	Do you have the OEM wiring goig to the pump, or a seperate circuit with new relay? S13 wiring is known to be insufficient for bigger pumps. If it's just stock wiring...run a new ciurcuit to the fuel pump. Use the stock fuel pump + wire to turn a relay on and provide a dedicated circuit just for the pump. See KA-T.org for a S14 install...S13 is almost identical: http://www.ka-t.org/tech - "Rewiring Your Walbro 255 Pump for S14's" Do that, report back with results... __________________ www.KA24DEvelopment.com

05-23-2005, 01:52 PM	#3
the head Nissanaholic! Join Date: Jul 2002 Location: in a dark room mastering the art of typing with one hand Posts: 2,164 Trader Rating: (3) Feedback Score: 3 reviews	Good thought I will just hotwire the pump 10 ga sould be sufficent for the power wire right? __________________ I never knew you could do that with an eggplant

05-23-2005, 02:57 PM	#4
RBS14 Nissanaholic! Join Date: Feb 2003 Location: Santa Cruz/San Diego Posts: 2,271 Trader Rating: (0) Feedback Score: 0 reviews	don't hotwire it, a relay cost's like $4. __________________

05-23-2005, 04:06 PM	#5
the head Nissanaholic! Join Date: Jul 2002 Location: in a dark room mastering the art of typing with one hand Posts: 2,164 Trader Rating: (3) Feedback Score: 3 reviews	That is how it is referred to where i am from if you are mainlining power to the pump we call it hotwiring with or without the relay I am using a relay __________________ I never knew you could do that with an eggplant

05-23-2005, 05:01 PM	#6
RBS14 Nissanaholic! Join Date: Feb 2003 Location: Santa Cruz/San Diego Posts: 2,271 Trader Rating: (0) Feedback Score: 0 reviews	oh ok, cool. __________________

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