Pretty sure the nissan ECU can't do pwm, you'd have to hookup another controller. Nistune should be able to be rigged up with a 1-5v output or just a switched output as inputs for the controller. Could probably also use the FPCU outputs for switching depending on voltages.
The stock fuelpump controller actually DO pwm. The ecu itself doesnt but it gives the FPC "orders" of what speed it wants. So you can just hook up the 485 to the FPC. Should look into upgrading the wires though. Or at least be aware of that the new pump draws more amps so it could be problems down teh line...
Same, I didn't think it was that smart.. Wiki states 3 voltages for tt and 2 for na. Even lists the voltages. What gave you the idea it was pwm? https://z32.wikispaces.com/Fuel+Pump+Control+Unit
Haha. Knew that would turn some heads. Yes it regulates voltage using pwm to do it (98% sure of it). https://en.m.wikipedia.org/wiki/Pulse-width_modulation
It's literally the first I've heard about it. If you know so much about it why not make one of your fancy graphs to show us the frequency a tt fpcu runs on each of its 3 stages. Or even if stage 3 which is battery voltage is controlled at all. I have only ever read a fpcu voltage on dc not ac so yeah...
Lol. I never measured it when i had one in my car Should be easy enough to check tho. Just use the hz setting on a dvom at the pump wires to see the hz. And use the dutycycle setting to meassure... well, the dutycycle... I could be wrong but dont think so. Im no electrical engineer at all but how else would it be done? Resistors. Would be some beefy ones i beleive and i cant recall anyone beeing in there. Transistors on the other hand...
I had assumed some dodgy resistor setup or maybe a little transformer if they were feeling fancy. Just went out and probed some wires though, no frequency on the white or orange but getting an unstable reading on the one with the black sheath/blue sheath (swaps from one side of the connector to the next). Just a cheap multimeter with frequency function so maybe polling period is too short. Not familiar enough with what each wire connects to or how pwm and other voltage steppers work to tell you what that means though. Edit: Just looking at the wiring diagram, is the sheathed wire a shield?
Did some quick googling on some downtime and came up with this http://forums.nicoclub.com/fuel-pump-controller-module-voltage-drop-wire-or-signal-feed-t487062.html Bottom post. Now this is for a Q45 but some more googling pictures of that one looks alot like the z32 one so i dont think it is much different inside. This guy states it works at 20 000 Hz so that might explain why your multimeter wont read it Fists.
That's interesting, another field they were ahead of the game? Googling I'm getting references to later cars with that sort of hardware. I have seen a 485 running off the stock controller though and it didn't work very well, not sure if Madcow will remember the details but pretty sure his pump running off the controller wouldn't even make pressure at idle. May have been a current issue but probably not easy to beef up the controllers power rating.
Hm as far as understood the OP he is running 485 on stock fpcu with too much pressure? Maybe i got his issues wrong.
Right you are, unless someone else has bypassed the controller we must have had other problems at that point too. Once the pump was running the R33 Nismo reg was definitely too small.
Yeah, it's running high pressure with the 485. There is a chance though that the fpcu has been bypassed by a previous owner but I doubt it by looking at it. Maybe I just got lucky
Sorry for the tangent but I wanted to check that my original guess of using a resistor wasn't too unreasonable, looks like those cheap uncivilised R33s use one. http://www.sau.com.au/forums/topic/137043-fuel-pump-control-module-dropping-resistor/ Will be interesting to see how you go with reg upgraded. If you are currently running through the FPCU it does mostly rule out the possibility of using it to solve the pressure problem though.
Sure looks like it. https://www.aeromotiveinc.com/340-stealth/ "Turbine pump mechanism increases durability and can be used in pulse modulated applications."
Not totlay related but just came over this one. Could be intresting for people with aftermarket ecus that wants an easy way to PWM their pump. http://www.nzefi.com/product/fuel-pump-pwm-speed-controller/
J3bba.. As it turns out the 485 draws alot of current. The FPCU seemingly have a tendency to crap out because of it. Ashspez in the us sells an upgraded controller that can take the abuse. You should probably invest in one (or some other solution for that matter). I had one of those for several years with two pumps hooked up to it and it never failed. I sold it a few months ago after having it on the shelf for years though... Just dont order one from Ash himself. Find some other shop that sells it http://ashspecz.com/shop/prodInfo2.php?prodID=19 Here is a read or two for you https://conceptzperformance.com/blog/defeating-the-stock-fuel-control-system/ https://conceptzperformance.com/blog/defeating-the-stock-fuel-control-system-addendum/
