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Old 04-04-2015, 09:24 AM   #1
some dude
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Default Fuel pump electricity Q

I have a stock '06 WRX with a Walbro 255lph FP. I'm having a problem with a seal going out on the fuel pump hanger and I want to know how power is delivered to it. I've read of ppl hard wiring their pumps for 100% (duty cycle?) and I'm wondering if there is a variable voltage applied to the pump?

I know about the pressure regulator, what about power regulation?
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Last edited by some dude; 04-20-2015 at 07:05 AM.
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Old 04-05-2015, 01:10 PM   #2
Razgeiz
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In stock form there is a controller for how much fuel pump duty there is, now if your tune runs various duties you'd have to look at the tune however. Hardwiring gives more juice and 100% duty at all times.
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Old 04-05-2015, 01:16 PM   #3
veritasaequitas
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There is a section about this on here. I believe you run the hardwire to the pump than the ground gets sent to the fpcm and that regulates the duty cycles and works just fine without blowing up the fpcm
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Old 04-06-2015, 01:58 PM   #4
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Low side PWM driver.

hardwire will give the same voltage (a little less drop at full duty) but 100% duty cycle, so the pump will always be balls out, fuel will be hotter.


The wires going to the pump itself are nothing more than ~18AWG or so, and these plus the inductance of the coil itself limit the amount of power that the pump can consume. ie running a 1/2" copper wire from your battery is dumb, Ohmic losses in this situation mean little. I built a PWM driver and cnc'd the housing from 6061, a decent sized electrolytic cap ensures plenty of peak current available to the circuit. It still runs at the variable duty too.

Pre Potting epoxy


Last edited by ALOKIN; 04-06-2015 at 02:20 PM.
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Old 04-09-2015, 06:52 PM   #5
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Quote:
Originally Posted by ALOKIN View Post
Low side PWM driver.

hardwire will give the same voltage (a little less drop at full duty) but 100% duty cycle, so the pump will always be balls out, fuel will be hotter.


The wires going to the pump itself are nothing more than ~18AWG or so, and these plus the inductance of the coil itself limit the amount of power that the pump can consume. ie running a 1/2" copper wire from your battery is dumb, Ohmic losses in this situation mean little. I built a PWM driver and cnc'd the housing from 6061, a decent sized electrolytic cap ensures plenty of peak current available to the circuit. It still runs at the variable duty too.

Pre Potting epoxy

I need this. MEOW
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Old 04-09-2015, 07:26 PM   #6
I--RIDE--BIKES
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How much does directly hardwiring the fuel pump for 100% duty cycle lower the pumps lifespan vs hardwiring it with ground through the controller to get varying duty cycles?
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Old 04-09-2015, 09:15 PM   #7
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Quote:
Originally Posted by Razgeiz View Post
I need this. MEOW
I had to test a few before I started slingin em...noimsayn Ive had mine in for 6 months now and its chugging along just fine.


PM me, Ill gibs you teh hookup


Quote:
Originally Posted by I--RIDE--BIKES View Post
How much does directly hardwiring the fuel pump for 100% duty cycle lower the pumps lifespan vs hardwiring it with ground through the controller to get varying duty cycles?
That info would be in the spec sheet of any pump. My main concern is overheating the fuel.
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Old 04-14-2015, 10:07 AM   #8
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Quote:
Originally Posted by veritasaequitas View Post
There is a section about this on here. I believe you run the hardwire to the pump than the ground gets sent to the fpcm and that regulates the duty cycles and works just fine without blowing up the fpcm

Is this true? I believe that's how I hard wired mine early last year I am now wanting to step up in fuel pump size to something like the walbro 400 and just want to make sure I won't be frying my Fuel pump controller.
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Old 04-14-2015, 10:14 AM   #9
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http://forums.nasioc.com/forums/show....php?t=2382384

I think it's 2 or 3 pages back it is quoted with a picture of how to use it. Somewhere in there I think page 5 is the original post
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Old 04-20-2015, 07:02 AM   #10
some dude
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Default Fuel pump electricity Q

Take a listen to this 3rd gear pull. Only to about 4700rpm or so, the pump changes pitch/sound and goes back to normal at the end. When the pump makes this noise, the car instantly loses lots of power and starts hesitating/stuttering.


Last edited by some dude; 04-20-2015 at 06:13 PM.
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Old 04-25-2015, 11:51 AM   #11
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Quote:
Originally Posted by ALOKIN View Post
Low side PWM driver.

hardwire will give the same voltage (a little less drop at full duty) but 100% duty cycle, so the pump will always be balls out, fuel will be hotter.


The wires going to the pump itself are nothing more than ~18AWG or so, and these plus the inductance of the coil itself limit the amount of power that the pump can consume. ie running a 1/2" copper wire from your battery is dumb, Ohmic losses in this situation mean little. I built a PWM driver and cnc'd the housing from 6061, a decent sized electrolytic cap ensures plenty of peak current available to the circuit. It still runs at the variable duty too.

Pre Potting epoxy

Does your pwm controller take in the ecu pwm signal and use a larger gauge battery Cable to pulse a higher voltage? Or is it for yarding out the ecu in favor of one that doesn't pwm control the fuel pump?

- thanks!
- Isaac
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Old 05-27-2015, 08:01 PM   #12
some dude
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Default Fuel pump electricity Q

I need a little help with why something is happening to my car and it is related to the fuel pump.

I have a thread in 2.5L with pictures of the seal i am talking about.

http://forums.nasioc.com/forums/show....php?t=2699693

I just blew out the 2nd one in under 500 miles. My car is pretty much stock, supposedly my original fuel pump went out so I bought a Walbro 255 and put it in my stock fuel system car. Well something is up because my fuel system cut a brand new rubber seal in half. How much pressure would i need to do that?

Why is this happening? I was under the impression that throwing in a 255lph fuel pump would not be a problem for a stock car.

I also would be interested to know the pressure / flow specs for a stock fuel pump, and the specs for the Walbro.


Edit: I found Walbro specs but not the stocker's.

Last edited by some dude; 05-29-2015 at 07:17 AM.
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