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Fuel pump control module


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Making that change would be easy, but why would anyone do this?

 

Thanks for chiming in rao. I figuired why run the pump at less than 100%?

 

Why does Subaru do this? I just want smooth consistant fuel delivery from this pump before I tune since my IDC's are up pretty high.

 

Your thoughts are apprecieated! ( Sorry, I'm going to make you type today:lol:)

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Paul, have you looked into 08+ WRX & Sti pumps ? I was looking at 245lh ones AVO is selling for 05 LGT with variable voltage support, and they list it as compatible with 08+ Wrx, Sti and FXT. My thought was to get one of those and retrofit it into my LGT. I was wondering what the flow is on those pumps. Don't think I like the idea of fuel pump running at 100% capacity all the time.

2005 LGT Wagon Limited 6 MT RBP Stage 2 - 244K

2007 B9 Tribeca Limited DGM - 243K

SOLD - 2005 OB Limited 5 MT Silver - 245K

SOLD - 2010 OB 6 MT Silver - 205K

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I have debated for a while installing a relay to make the Walbro get full power all the time.

 

Only because the Walbro is not designed to run at different voltages. Sure any 12vdc electrical motor will operate at about 5-6 volts. Even many 110v motors will operate at less voltage (just hook them up to a light dimmer and watch). But I am hearing that the failures associated to Walbros (fewer than the rumors portray) are most likely due to feeding them low voltage and causing the motors to overheat and fail.

 

Rao, any thoughts (honestly, not sarcasm).

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I have debated for a while installing a relay to make the Walbro get full power all the time.

 

Only because the Walbro is not designed to run at different voltages. Sure any 12vdc electrical motor will operate at about 5-6 volts. Even many 110v motors will operate at less voltage (just hook them up to a light dimmer and watch). But I am hearing that the failures associated to Walbros (fewer than the rumors portray) are most likely due to feeding them low voltage and causing the motors to overheat and fail.

 

Rao, any thoughts (honestly, not sarcasm).

 

m sprank......exactly my thoughts on this. The OE pump is designed to run on lower voltage but can the Walbro stand up to this?

 

sub op, I'll look into the Sti pump.

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The ECU can only deliver a limited amount of electrical power. If you put in a big pump or more than one that need a high current draw to reach its rated pressure, the stock ECU might not be able to supply enough juice. For now, on my friend's car with dual Walbros we have relays in place drawing current directly from the battery. I have a background in power electronics so I am designing a circuit that will use the stock fuel pump control to reduce the speed of the pumps for idle and low load situations.

 

Why would lower voltage cause a motor to overheat and fail?

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NSFW has found the fuel pump duty cycle tables but right now it's not a standard definition. Apparently it's different in each ROM revision so he's got to manually locate it for each ROM.

 

Once it's been made available for all ROMs, it's simply a matter of typing in 100% for all values -- no hardware change required. I'd want to do this even if I went to a relay so it'd have a steady trigger input.

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I have debated for a while installing a relay to make the Walbro get full power all the time.

 

Only because the Walbro is not designed to run at different voltages. Sure any 12vdc electrical motor will operate at about 5-6 volts. Even many 110v motors will operate at less voltage (just hook them up to a light dimmer and watch). But I am hearing that the failures associated to Walbros (fewer than the rumors portray) are most likely due to feeding them low voltage and causing the motors to overheat and fail.

 

Rao, any thoughts (honestly, not sarcasm).

 

That is complete BS.

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NSFW has found the fuel pump duty cycle tables but right now it's not a standard definition. Apparently it's different in each ROM revision so he's got to manually locate it for each ROM.

 

Once it's been made available for all ROMs, it's simply a matter of typing in 100% for all values -- no hardware change required. I'd want to do this even if I went to a relay so it'd have a steady trigger input.

 

I think the switching frequency is high enough where the relay stays closed but I haven't had a chance to measure it directly yet. I'm waiting on a high-speed DAQ card to do it.

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Would you like me to type this 100 times?

 

THEY DO IT FOR EVAPORATIVE EMISSIONS REASONS.

 

It will not bother your latency settings or anything else- don't *^$#$#$% with it :)

 

I'm sorry to annoy you rao, I did not know that. :) Please type it one more time and make it 101 times. ;)

 

OK, so I won't (*&^#$(*& with it!

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Thanks Rao. I too questioned why the pump could not take the lower voltage. Not like its pulling more current. But you know how the interweb is. Lots of good BS to read. I have not had an issue with just hooking mine up to the OEM electrical connection. Just read a bunch of crap about possible causes of failures.

 

If its good enough for Rob, its good enough for me.

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So if I wanted to use a Weldon pump or a Fuel Labs pump, would it be best to wire it to a relay and let it run at 100% all the time or hook it up directly to the factory wiring? According to fuel labs, you can run their pumps without an external controller and it can be run on the factory wiring. I dont know how true that is.
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You could start by hooking it up to the stock wiring and see if the pressure is high enough for your needs, since the supply current from the ECU might be limited. If not, then you can run it with a relay and run it at 100% with current drawn straight from the battery. Fuel pumps can get pretty noisy running at 100% all the time though :lol:
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Actually the Fuel Lab pumps have a built in controller so that you don't have to run it 100% all the time. It does 66% at low mode and 100% at high mode that is switchable through any 0-5v source.
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TI have a background in power electronics so I am designing a circuit that will use the stock fuel pump control to reduce the speed of the pumps for idle and low load situations.

 

How about just use the stock ECU PWM output to drive a power mosfet? You really have no reason to run the thing at 100% most of the time (it will DECREASE the life of the pump), just let the ECU do it's thing but with less total inline resistance fore the pump?

 

Does the fuel pump controller vary the voltage through resistors? Or is the pump somehow pulsewidth modulated?

 

It's PWM.

Edited by utc_pyro
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