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Help With Rb25 Neo Swap Fuse Keeps Blowing

amnash

By amnash,
in Engines & Forced Induction

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amnash Enthusiast

amnash

Posted
Posted

im in the process of my rb25 neo swap and everything is done, its just a matter of wiring and getting it to start up. the r34 engine harness is all set up to plug into the r32 chassis wiring. i cant figure out my my fuel pump fuse keeps blowing. ive gone through three 15amp and one 20amp fuses.

im completely stumped as to why it keeps blowing. it worked fine with the rb20 installed. the only part of the circuit ive tampered with is the ecu fuel pump relay wire on the engine harness and that's now hooked up to were the rb20 fuel pump relay wire was connected to the chassis wiring so it should be fine. the signal voltage seems to be good and everything but after a second or 2 the fuse blows...

any ideas? anyone that's done a rb25 swap run into this problem??

89CAL Grand Master

89CAL

Posted
Posted

Is there a difference between the way R32's and R34's control the pump? The resistor pack for the fuel pump may be different, I'm sorry I cant be much more help then that but I had a funny feeling there was a difference somewhere there. Not sure if that will be the problem but

amnash Enthusiast

amnash

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  • Author
Posted (edited)

i have no idea, and im stumped. everything worked fine before, now with the r34 ecu it doesnt wanna work

im hoping there's someone on here thats put a neo into a r32 and can help me out a bit

Edited by amnash
amnash Enthusiast

amnash

Posted
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so after measuring some voltages on the relay pins i think the ecu isnt sending the signal to ground the pump relay. i checked both the r32 wiring and r34 wiring and they are the exact same for the fuel pump. any ideas why the ecu wouldnt be sending the signal?

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amnash Enthusiast

amnash

Posted
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could someone take a multimeter to there car and read the voltage or resistance on the fuel pump relay pin on ecu? that would be a huge help because then i would at least know what to aim for

amnash Enthusiast

amnash

Posted
  • Author
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well they dont look the same but if you trace the wires, its exactly the same. the pins are in different spot on the ecu plugs but should be doing the same job. it might be the drop resistor your talking about, anybody know where it is?

kitto Mentor

kitto

Posted
Posted

Get rid of the fuel pump control module for a start. Hard wire the fuel pump negative terminal to ground.

Ignore pin 111 on the ECU. Your only concern is pin 13. This grounds the fuel pump relay. On ignition on it grounds the relay for 4 seconds. When CAS signal is seen the ECU grounds this pin full time. When it isn't grounded you'll see an open circuit/high resistance.

If your fuse is constantly blowing find the short. DO NOT put bigger fuses in, you'll start melting your wiring. Bigger fuses are not the answer to a fuse that keeps blowing.

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