Fuel pump control module

[Scooby2.5]

I saw you said the voltage drop from the FPCM to the pump was a 1v loss.

 

This could be because of the output of the stock legacy FPCM or it most likely is due to the gauge of wire going to the pump from the FPCM.

 

You may have to go the extra step as I think integroid did and run a new wire direct to the pump from the FPCM.

 

I will eventually be doing this to mine as I am barely at the 13.5-13.7 volts needed for the pump.

 

My alternator is a bit weaker than some (183K on it) and its only putting out 13.8 so of course I will be less at the pump due to the voltage drops.

[mwiener2]

You still don't get it or no one knows how to properly measure fuel pressure.

 

We have a return fuel system. The Fuel Pressure Regulator bypasses fuel to get the pressure it wants.

 

So if your fuel pump isn't flowing enough, there is no fuel to bypass, and fuel pressure does not rise 1:1 with boost. If you do have enough fuel pump, then fuel pressure will always rise with boost 1:1 and hold.

 

If fuel pressure rises and holds 1:1 with boost, and you are still having fuel delivery problems, it's not the fuel pump.

 

 

 

I'm glad you "went through all this with my car on E85 at higher horsepower" but I've been through this on hundreds of cars. If fuel pressure is good, then it's not the fuel pump.

 

If Coldsubycz's tuner says fuel pressure is good, but the car is still lean, and Coldsubycz ups the volts to his pump and then fueling is fine, he should look for another tuner.

[Scooby2.5]

I'm glad you are not my tuner

 

I'm glad you are smarter than aeromotive

 

I'm glad you are smarter than Tim Bailey

 

I'm glad you are smarter than Calvin Dotson

 

Voltage to the pump does make a difference on flow and IDC

 

I Just quoted that to you from the pump manufacturer and you still don't believe it.

 

I've seen it with my own eyes exactly what aeromotive is saying.

[Scooby2.5]

For the record we put an aeromotive fuel pressure regulator on my car set to the factory 43 PSi

The IDCs were in the 100% range as soon as we applied bat/alt voltage to the pump like aeromotive says to do the IDC went way lower and allowed us to get it to 90% at 385whp 425tq.

 

But hey what do I know, I guess there is no reason at all to have your pump running at the voltage listed in their flow data sheet.

Edited August 1, 2012 by Scooby2.5

[doccrowley]

Wow, a pissing contest.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Here's my experience: I paid 4 hours labor in May 2012 to have all of these voltages tested: @ battery, @ alternator, @ fpcm from battery, from fpcm to pump. I had no voltage loss across the board and my fpcm was not the reason for fuel pressure loss at WOT. Initial thought was that my walbro 255 did not survive the switch to e85 after 5 months. Switched to a DW300 and still had issues with losing fuel pressure at WOT and car running lean.

 

After 4 hours of testing it was determined that I had issues with o-rings in the fuel pump basket. Further testing was done to determine what sealed best and showed zero loss of fuel pressure at WOT with a CNG o-ring. Single o-ring set-up for me.

 

All of my testing was done at Metric Motors, Utah and I replaced a Walbro 255 for no good reason other than I love that the DW is silent on power up rather than that stupid noisy Walbro!

 

Good luck figuring out your IDC's and fueling needs at WOT. Mine was much more basic than re-wiring the system as proposed here.

[mwiener2]

It's not a pissing contest, it's him not quite understanding whats going on. I'm not arguing with him, I'm telling him how it is, and he replies by telling me he knows better, but doesn't say why.

 

I understand you set an Aero to 43psi and blah blah blah. I'm not arguing that you have spent alot of time with this. What was the fuel pressure at redline? Was it 1:1 with boost? If you were going lean, it probably wasn't 1:1 with boost. But you can't answer that question because you're too busy being king of the hill. Pull your head out of your rear and READ what I've said. I've told you how to diagnose an inadequate fuel pump, you've figured out why they don't flow enough on a Legacy.

 

 

 

 

I am trying to tell Coldsuby that HE may not have the same problem that Scooby2.5 does. But Scooby2.5 just wants to be the king of the hill in this thread.

 

 

If you need 300 l/h of fuel and you put in a DW300 you might only get 250 out of it becasue of the lower votlage and the pump not working at it's full capacity. But if you then throw in a walbro 460 l/h, it may still pump 320 l/h at the lower voltage. You have enough fuel without raising the voltage. It's not ALL about the voltage. This is also besides the fact that a 460 would fry the FPCM because it draws 20+ amps.

 

 

To properly measure fuel pressure, you must be able to have the car at full load to take a reading. This is usually only doable on a dyno or if you have an in cabin gauge. So if you aren't taking fuel pressure readings at WOT at redline, you aren't doing it right.

Edited August 1, 2012 by mwiener2

[TheOneDoubleN]

.

[coldsubycz]

This brings up a good question for me. I have the DW65c pump (flows about 265lph at 13.5v). What size fuse have people been using at the battery back to the "new" relay/FPCM? I picked up a 30amp going off of the Aeromotive wiring kit info. mwiener2 brought up a comment about that bigger pump pulling 20+ amps. I don't think I'll have that issue with the DW65c (I think it maxes at 14.6 amps), but is a 30 amp maybe too big?

[Scooby2.5]

It's not a pissing contest, it's him not quite understanding whats going on. I'm not arguing with him, I'm telling him how it is, and he replies by telling me he knows better, but doesn't say why.

 

I understand you set an Aero to 43psi and blah blah blah. I'm not arguing that you have spent alot of time with this. What was the fuel pressure at redline? Was it 1:1 with boost? If you were going lean, it probably wasn't 1:1 with boost. But you can't answer that question because you're too busy being king of the hill. Pull your head out of your rear and READ what I've said. I've told you how to diagnose an inadequate fuel pump, you've figured out why they don't flow enough on a Legacy.

 

 

 

 

I am trying to tell Coldsuby that HE may not have the same problem that Scooby2.5 does. But Scooby2.5 just wants to be the king of the hill in this thread.

 

 

If you need 300 l/h of fuel and you put in a DW300 you might only get 250 out of it becasue of the lower votlage and the pump not working at it's full capacity. But if you then throw in a walbro 460 l/h, it may still pump 320 l/h at the lower voltage. You have enough fuel without raising the voltage. It's not ALL about the voltage. This is also besides the fact that a 460 would fry the FPCM because it draws 20+ amps.

 

 

To properly measure fuel pressure, you must be able to have the car at full load to take a reading. This is usually only doable on a dyno or if you have an in cabin gauge. So if you aren't taking fuel pressure readings at WOT at redline, you aren't doing it right.

 

I agree with this explanation no problem with the exception I have my head up my rear and Im trying to be king of the hill

 

At least that was more descriptive than your first couple of posts.

 

I would say he needs to eliminate the Voltage problem FIRST and then go from there....

 

His DW pump may still not flow enough who knows but if the voltage is not up to par we will never know.

 

Wouldnt you suggest he FIX the voltage problem before he pays to get back on a dyno?

 

 

As far as Cold's question on the amperage of the fuse. In the instructions from Aeromotive they use a 30 amp.

 

DW sells the same rewire kit and you could look at it and see what they are using.

 

Hope that helps Cold

[mwiener2]

Sorry for being so harsh.

 

The fpcm is designed for a pump that never draws more than 20a because that's the fuse Subaru put in there. Evan at 15a, you guys have found undersized wiring. In my opinion, anything larger than 300l/h should have dedicated wiring and the only way to cycle it world be to get an aftermarket controller.

 

You guys have over stressed controllers that could fail at any time.

[Scooby2.5]

I guess we will see but Im sure many a STI owner are running the STI module still in their car.

 

Just for information sake take it or leave it....

 

Looks like the Aeromotive doesn't go above about 19 amps as shown by their chart and this statement from the FAQ:

"As pressures go higher, so goes current draw, with a peak of 19 amps at 90 PSI pressure."

 

http://static.speedwaymotors.com/images/charts/340-Flow.gif

 

 

Here is the test real street performance did on the aeromotive:

http://www.realstreetperformance.com/ebay/real_street_performance_fuel_pump_test_flow_chart.jpg

 

.........but with specific regard to the “pulse modulation” aspect, unlike most aftermarket in-tank style pumps, the Aeromotive 340 Stealth Pump is fully compatible with aggressive speed control strategies. One of the many features that make the 340 Stealth pump unique is the “turbine” style pumping mechanism. This type of pump is much more tolerant of the aggressive type of “Pulse Modulation” method of controlling pump speed, employed by the factory engineers, to create flow and control fuel pressure.

Unlike positive displacement pumping mechanisms, “turbine” rotors are not radically affected by the inertial forces related to the aggressive starting and stopping that is caused by the low frequency pulse modulation needed to vary fuel pressure by up to 30 PSI. Aggressive pulse modulation can “cog” a conventional pumping mechanism to pieces by locking it up in both directions on a continuous basis. The Aeromotive Stealth 340 Pump features the same “turbine” style pumping mechanism used by many OEM’s in these same applications, providing potentially excellent reliability in a speed controlled fuel system which has been properly re-engineered to take advantage of the Stealth 340’s high-flow capabilities.

Edited August 4, 2012 by Scooby2.5

[mwiener2]

I just replaced a FPCM on an 08 Sti two weeks ago. They fail too.

 

 

I'd like to know how they tested and at what voltage they tested the pumps as they didn't even hit the Walbros rated 255 l/hr.

 

 

You also have to consider none optimal conditions. There are certain conditions in day to day driving where the vehicle voltage can fall to 11.5v or sometimes lower. The fuel pump draws significantly more amperage in these instances and the wiring needs to be able to handle it.

[Scooby2.5]

I looked at the parts database again. So 05-09 LGT/OBXT part # is 22648AA081. Regardless of wagon or sedan.

 

The same part # is used on 08-10 WRX sedan. 08-10 STI and 08-10 WRX hatches use 22648AA140 part #.

 

It's crazy this one is $340!!! 08+ one is $90....

 

Maybe there is a quality difference...

 

We are changing the wiring...

Edited August 4, 2012 by Scooby2.5

[Scooby2.5]

I just replaced a FPCM on an 08 Sti two weeks ago. They fail too.

 

 

I'd like to know how they tested and at what voltage they tested the pumps as they didn't even hit the Walbros rated 255 l/hr.

 

 

You also have to consider none optimal conditions. There are certain conditions in day to day driving where the vehicle voltage can fall to 11.5v or sometimes lower. The fuel pump draws significantly more amperage in these instances and the wiring needs to be able to handle it.

 

13.2 Volts, sorry it was cut off the picture....

http://realstreetperformance.com/store/pages/fuel-pump-comparison-test-5.html

 

Also here is the amperage chart

 

http://www.realstreetperformance.com/ebay/real_street_performance_fuel_pump_test_amperage_graph.jpg

Edited August 4, 2012 by Scooby2.5

[Aracheon]

Wow, a pissing contest.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Here's my experience: I paid 4 hours labor in May 2012 to have all of these voltages tested: @ battery, @ alternator, @ fpcm from battery, from fpcm to pump. I had no voltage loss across the board and my fpcm was not the reason for fuel pressure loss at WOT. Initial thought was that my walbro 255 did not survive the switch to e85 after 5 months. Switched to a DW300 and still had issues with losing fuel pressure at WOT and car running lean.

 

After 4 hours of testing it was determined that I had issues with o-rings in the fuel pump basket. Further testing was done to determine what sealed best and showed zero loss of fuel pressure at WOT with a CNG o-ring. Single o-ring set-up for me.

 

All of my testing was done at Metric Motors, Utah and I replaced a Walbro 255 for no good reason other than I love that the DW is silent on power up rather than that stupid noisy Walbro!

 

Good luck figuring out your IDC's and fueling needs at WOT. Mine was much more basic than re-wiring the system as proposed here.

 

 

 

 

Doc: do you have a link to where you purchased that O-ring from? How did they determine that it was a problem with the O-ring in the first place?

[coldsubycz]

Finally got somewhere with this. Still not finished as I have to "clean it up a bit". I still have some wires hanging. Tonight I just want to get it up and running. I wanted to test some voltage to see the improvement. I've included some pictures for your view enjoyment

 

These readings are now with the new wiring/STI FPCM in place.

14.0v - At the battery

14.0v - At rear distibution block and new relay

13.5v - At the fuel pump (Tested during the first 10 seconds after startup)(Improved by 1v over stock wire)

07.7v - At fuel pump idle (improved 0.7v over my stock wire at idle)

 

Now I have to go back for a tune.... again... and hope this 1v increase solves the problem.

 

All wire in the back is 10 gauge. Even soldered onto the FPCM pins (pain in the butt!). I used 4 guage from the battery to the back (future stereo plans).

 

I have more pictures, but don't have the time tonight to post and write this up. That will come in the following weeks.

[Scooby2.5]

Thats about exactly what I got. My alternator only puts out about 13.9-14.0 as well.

 

If you change the line to the pump you will see closer to 14 at the pump.

 

I didnt do this either but may at a later date.

 

13.5 is what my Aeromotive pump was flow tested at.

 

Cold what are your other mods on this car.

 

Just curious what you have and what you are trying to achieve

[coldsubycz]

^ The funny thing is I ran 10 gauge from the FPCM to the pump. I soldered the 10awg about 1" from the pump plug so there is 1" of 18awg wire to the pump. I was not able to get my voltmeter probes into the harness at the FPCM. I think the STI FPCM might be dropping the 1/2 volt. I'll see what I can do tonight about getting a better reading.

 

I was hoping to get 300hp on 91 pump, but that ended up being 278hp. On e85 I was hoping for 340+hp.

 

As for mods:

ELH

TBE full 3"

PW TMIC

TGV deletes

ID 1000's in parallel

[mwiener2]

stock turbo?

[Scooby2.5]

He has an AVO380 I believe.

 

when I had really crappy 91 or advertised 93 (which it wasn't ) I think if I remember correctly I did like 307/325 with the small AVO TMIC.

 

You should get to that I would think pretty easy and I wouldnt think on 91 you would be having IDC problems and be needing to do the FPCM mod.

 

I hate to discourage but it sounds to me something else is the issue.

 

Only time I ever had IDC problems was running E85 (30% more fuel) at close to 400 WHP.

Edited August 9, 2012 by Scooby2.5

[Scooby2.5]

THANK YOU, THANK YOU, THANK YOU for this thread starting at post #42!!!! Scooby2.5 your work on this is unbelievably helpful.

 

Got a call from my tuner today saying he was having troubles with my car. Said my injectors were maxed out on e85 (ID1000's and DW65c), but other parts of the system were telling him he had room to go. He said it seemed like the pump was not giving "it's all" so to speak. I remembered this thread and sent it to him. So now I have to get the module and discuss all the fun wiring that needs to be done.

 

Nevermind Cold went back through the thread and see that you were tuning for E85.

 

Not sure about your low numbers on 91 though. Could have been the fuel.

 

Ask your tuner if it was knocking and thats why he had to quit.

 

My first tune at cobb on pump gas was terrible because he could not get it to stop knocking so he had to stop pushing it.

 

That tune is when all the AVO380 bashers started LOL

 

Once I got some good gas and a FMIC.......the rest is history.

[coldsubycz]

My stock HP on the same dyno was 185. My tuner says that stage 2 STI's don't get over 300 on his dyno.

 

And yes I have an avo380

[Aracheon]

I have more pictures, but don't have the time tonight to post and write this up. That will come in the following weeks.

 

 

 

I'd be interested in seeing how you ran the 10awg wires to the plug at the fuel pump itself. Those connectors are a lot smaller than the ones at the FPCM.

[coldsubycz]

I'd be interested in seeing how you ran the 10awg wires to the plug at the fuel pump itself. Those connectors are a lot smaller than the ones at the FPCM.

 

I cut the "18 gauge" wire 1 inch from the pump connector and soldered my new 10 gauge onto that. My solder job was pretty bad, so no pictures of that. If I were to do it again I would have used a "step down butt splice" and then some heat shrink tubing.

[Aracheon]

Oh.

 

That's cheating.