Fuel pump control module

[integroid]

I agree with Scooby and have already been down that road of wiring my fuel pump to a relay running 100% all the time. What Scooby has posted and I have validated works perfectly.

[ClimberDHexMods]

My thought was:

Leave the FPCM to run stock so you get stock PWM 98% of the time. During the 2% when you're on boost, a boost switch activates a relay, which switches power feed away from/through the FPCM, and instead direct heavy gauge wire from the battery to the pump. One could add a KB BAP so that the 14V is instead 17 or 19V, whatever you need to keep up fuel pressure.

 

I have not fiddled with the realities of such a setup. Are you guys saying you tried this style of setup, and it was too messy and unnecessary? The only big difference I see between this and a 100% on relay powering the FP is the addition of a boost switch (I realize those can fail, but that's a different story).

[Scooby2.5]

There is no reason to do this the system as we wired it runs the PWM duty cycle just as it should and it gets the proper voltage that the pump needs. The pumps are flow tested at 13.5 volts or so generally, so thats really all you need.

When you are on boost or at full load the FPCM runs full duty cycle anyway so there is no need to switch the power feed under boost.

[ClimberDHexMods]

There is no reason to do this the system as we wired it runs the PWM duty cycle just as it should and it gets the proper voltage that the pump needs. The pumps are flow tested at 13.5 volts or so generally, so thats really all you need.

When you are on boost or at full load the FPCM runs full duty cycle anyway so there is no need to switch the power feed under boost.

 

Can the mid-sized pumps (such as DW300) pull their listed amps at high pressure levels through the wiring you have it setup as? If so, you guys really knocked this one out of the park

 

Edit: Nevermind, I re-read, you definitely have the best solution here.

Edited July 26, 2012 by ClimberD@HexMods

[Scooby2.5]

We didn't really knock it out of the park. This is the suggested way to wire it from DW, Aeromotive, Cobb etc.

 

The only difference is we are leaving the FPCM in the circuit (STI Module) because with the proper wiring it provides the voltage necessary and gives you the pulse width modulated signal so the pump in not running 100% duty cycle all the time.

 

Post 106 has some links to Aeromotive and how they tell you to wire it and both they and DW offer kits for rewiring your system as we did.

[Tandi]

Can you help explain where I can access this on the wagon? From inside the back hatch/trunk?

 

I just bought a 2002 wrx and was told this was the part throwing the check engine light.

 

 

I know this is Legacy, but hey- theyre all the same deep down right?

[Scooby2.5]

If you are talking WRX wagon I have no idea.

[technicalgarage]

Well, I have no intention of running e85 anytime soon due to availability, but I figured I'd get everything I needed just in case I do in the future.

 

Picked up a used 06 wrx fpcm with harness (pn: 22750AA010)

I decided not to do the actual wiring due to the reason above (which is, arguably the whole point of the modification), but instead just swapped modules and opened them up for the sake of comparison.

 

On the wagon, the fpcm is located in the driver's side (LHD) cargo area behind the interior trim next to the rear of the wheel well.

You can see the loom running around behind the sheetmetal to the fpcm here.

http://media.technicalgarage.com/media/car/bp9/fpcm/IMG_0065.jpg

 

Size wise, the 05 LGT part (pn: 22648AA081) and 06 wrx fpcm are identical.

The bracket holes are the same but the brackets themselves are different.

I have to say I like the look of the orange label a lot more though.

http://media.technicalgarage.com/media/car/bp9/fpcm/IMG_0068.jpg

 

The harness connections are the same. Like everyone says in the thread, the wrx/sti wiring is much thicker. Unfortunately the legacy harness is integrated into a loom and isn't two pieces like the wrx. (see photo 1). This photo is of the wrx harness, easily twice as thick as the lgt.

http://media.technicalgarage.com/media/car/bp9/fpcm/IMG_0060.jpg

 

Now comes the interesting part. I took apart both. Only noticed one obvious difference. The large orange caps have slightly different markings.

Other than that, the two modules look identical.

Whether or not they actually are though is questionable if not unlikely judging from people's experiences in this thread.

The left is the 05 LGT part, the right is the 06 wrx part.

http://media.technicalgarage.com/media/car/bp9/fpcm/IMG_0069.jpg

 

Legacy part:

http://media.technicalgarage.com/media/car/bp9/fpcm/IMG_0070.jpg

 

WRX part:

http://media.technicalgarage.com/media/car/bp9/fpcm/IMG_0071.jpg

 

Anyway,

 

Like I said, I just swapped the fpcm itself and nothing else.

Since I'm running gas it doesn't sound like it matters too much in my application. The car started and ran fine after swapping to the 06 wrx fpcm

I thought about taking voltage measurements but the weather sealing on the fuel pump connector was too tight for my multimeter probes so I gave up on that.

I just thought the internal comparisons were interesting to add to the thread.

[Scooby2.5]

Should be a flip top on the fuel pump connector. Flip it up and and you can test the voltage there. Best way to test it is just do key on as the FPCM goes 100% for a few seconds. That will tell you what the voltage is at full duty cycle.

[coldsubycz]

technicalgarage you beat me to the pictures!

 

I'm in the middle of doing this mod today on my sedan. I've been taking lots of pics. For those with the sedan and if you look at the vacation pics, don't follow them! It's for the wagon. The FPCM in behind the trunkliner on the driver's side. It's so easy to get too on the sedan. If only I went with my gut and not the vacation pics .

 

So I took my volt meter and did some tests. Very interesting. These are measured with the car idling. (the reason for the 7v measurement).

 

14.5v at the battery

13.4v at the input on the FPCM

07.8v at the output to the pump on the FPCM

07.0v at the fuel pump

 

Discuss.....

[mwiener2]

You have normal voltage readings

[coldsubycz]

I know..... what's up with that?.... My tuner said I was running out of fuel on e85 even with ID1000's and DW65c. My tuner said the fuel pressure was good it just seemed like the pump was not giving more in the upper RPM area. To me it sounded like the FPCM issue. My DW65c has two o-rings on it because when my installer used just the one the pump was unable to maintain pressure. When two were added everything was fine on my 91 pump gas tune. When I went e85 that's when the problems started.

 

So now I have this project halfway done. Might as well finish it and test the voltage when I'm done.

[mwiener2]

If the fuel pressure holds 1:1 with boost, then your Fuel Pump may not be the problem

[ClimberDHexMods]

Sounds like it could just as easily be a tuner problem as a tuning problem. Do you have a fuel pressure gauge?

[Scooby2.5]

technicalgarage you beat me to the pictures!

 

I'm in the middle of doing this mod today on my sedan. I've been taking lots of pics. For those with the sedan and if you look at the vacation pics, don't follow them! It's for the wagon. The FPCM in behind the trunkliner on the driver's side. It's so easy to get too on the sedan. If only I went with my gut and not the vacation pics .

 

So I took my volt meter and did some tests. Very interesting. These are measured with the car idling. (the reason for the 7v measurement).

 

14.5v at the battery

13.4v at the input on the FPCM

07.8v at the output to the pump on the FPCM

07.0v at the fuel pump

 

Discuss.....

 

Because you are measuring with the car idling I am assuming.

 

At idle the fuel pump is 33% duty cycle via the FPCM.

 

You need to measure in the few seconds at key on when the pump goes to 100% percent duty cycle.

 

You have your relay and battery wire, wired in like the drawing?

Edited July 31, 2012 by Scooby2.5

[Scooby2.5]

I know..... what's up with that?.... My tuner said I was running out of fuel on e85 even with ID1000's and DW65c. My tuner said the fuel pressure was good it just seemed like the pump was not giving more in the upper RPM area. To me it sounded like the FPCM issue. My DW65c has two o-rings on it because when my installer used just the one the pump was unable to maintain pressure. When two were added everything was fine on my 91 pump gas tune. When I went e85 that's when the problems started.

 

So now I have this project halfway done. Might as well finish it and test the voltage when I'm done.

 

If the fuel pressure holds 1:1 with boost, then your Fuel Pump may not be the problem

 

 

Sounds like it could just as easily be a tuner problem as a tuning problem. Do you have a fuel pressure gauge?

 

 

Guys, the fuel pump or tune has never been the problem, Have you even read this thread at all?

 

I have explained this pretty clearly I believe. No offense but you guys are worrying me. Don't blow your car up LOL!

 

The aftermarket fuel pumps are flow tested at battery and alt voltage or about 13.7 volts usually.

 

If you run less voltage to the pump you will flow less fuel.

 

The legacy FPCM and wiring is limiting the voltage to the pump.

 

When you need 30% more fuel on E85 at high HP the stock voltage via FPCM and wiring is not allowing the pump to run at its capacity and then you run out of fuel.

 

You need to have around 13.5-13.7 volts to the pump at 100% duty cycle. The way to easily test this is at KEY ON. The pump goes 100% duty cycle for a few seconds when you turn the key on for starting purposes.

 

Adding the relay, direct battery voltage and the STI module achieves this.

 

It also allows the pump to run less at idle and non full load situations.

Edited July 31, 2012 by Scooby2.5

[integroid]

If you rewired with a relay like we said, you would have close to 14.5V at the FPCM. If this will actually help you with your problem? I dont know for sure. Mine was dropping fuel pressure at the upper RPM range with the stock FPCM and wiring.

[mwiener2]

Scooby2.5 - If fuel pressure stays 1:1 with boost, then the fuel pump is keeping up, regardless of what voltage it is begin fed

[Scooby2.5]

We have proven that the voltage to the pump is causing the issues.

 

Read through this WHOLE thread and if you don't, don't just jump in this long conversation at this late in the game and post information not based on the context of the thread, it just confuses people.

Edited July 31, 2012 by Scooby2.5

[mwiener2]

Ok, but you're still not getting it. If the fuel pressure stays 1:1 with boost, then the fuel pump is delivering enough fuel. There is no issue.

 

 

If your fuel pressure does not stay 1:1 and drops, then you have an issue with fuel delivery that may be related to the voltage problems you've found.

 

Coldsubycz probably does not have an issue with the fuel pump. He may have another fueling issue, or possibly a tuner issue.

[coldsubycz]

I didn't mean to make people get upset. For that I truly apologize. This thread has been extremely informative and helpful and the time that others especially Scooby2.5 have put into this is invaluable. I have read the entire thread many times and fully understand what is going on. After reading my post where I measured the voltage I should have been clearer, I apologize for that.

 

All of my voltage readings are from a completely stock system. I did this so I would have a baseline reading to compare too. I was trying to give Scooby2.5 some more research info for this thread. It seems a good majority of GT's are giving 11.7 volts or so to the FPCM. For some reason my 05 GT is giving 13.4v to the FPCM with 14.5v at the battery while idling. I will do a test at the pump on startup. I had to hold the probes in the fuel pump harness so at the time I was physically unable to do start up test (my wife was with the kids so she was unable to help at the time).

 

For me what was interesting was even though my battery output was 14.5v my harness lost 1v to the FPCM. And even though I tested the pump at idle I lost 0.8v to the pump from the FPCM (7.83v output at the FPCM - 7.00v at the fuel pump. So my pump is seeing 12.7v, 1v less then optimum according to DW65c specs.

 

When I finish the wiring (which might be awhile since I'm a father of a 2 year old and 4 year old so time is limited) I will report my findings.

[coldsubycz]

Ok, but you're still not getting it. If the fuel pressure stays 1:1 with boost, then the fuel pump is delivering enough fuel. There is no issue.

 

 

If your fuel pressure does not stay 1:1 and drops, then you have an issue with fuel delivery that may be related to the voltage problems you've found.

 

Coldsubycz probably does not have an issue with the fuel pump. He may have another fueling issue, or possibly a tuner issue.

 

When I finish up my FPCM wiring project I will have my tuner/shop truly test the fuel pressure with a gauge.

 

When my tuner mentioned that he could not get much hp over my pump tune I was a little confused because even if my car was not outputting full 13.5v, even if it was 2v lower I should have still made a little more hp. Even though Scooby2.5's system was not full voltage a few years ago he was still getting a lot more hp over his pump tune. Not sure if I'm liking my tuner anymore. I'd really like to go down to Cobb, but that is so far away for me right now in my life.

 

I'll get this wiring done first, schedule up for a tune AND troubleshooting and see where that takes me.

 

I thank ALL of you guys for your help. I'm still amazed at how smart you guys are.

[Scooby2.5]

Ok, but you're still not getting it. If the fuel pressure stays 1:1 with boost, then the fuel pump is delivering enough fuel. There is no issue.

 

 

If your fuel pressure does not stay 1:1 and drops, then you have an issue with fuel delivery that may be related to the voltage problems you've found.

 

Coldsubycz probably does not have an issue with the fuel pump. He may have another fueling issue, or possibly a tuner issue.

 

I "get it" just fine, trust me I went through all this with my car on E85 at higher horsepower.

 

Coldsubycz Said:

"My tuner said the fuel pressure was good it just seemed like the pump was not giving more in the upper RPM area

 

From Aeromotive.

 

fuel supply as measured by volume and pressure also known as fuel pump ‘head’. An important part of knowing how to meet this requirement is to understand the characteristics of a typical pump.

 

All types of pumps exhibit a decrease in flow with an increase in pressure regardless of the brand type and/or style: georotor, rotary vane, centrifugal, etc. Additionally if it is a modern day electric fuel pump it will also increase or decrease flow with an increase or decrease in voltage.

 

 

The factory fuel pump wiring may not be sufficient to handle the current draw of the Aeromotive 340 Stealth pump. To achieve the advertised flow at pressure, the use of an aftermarket wiring kit such as Aeromotive P/N 16301, including 10-gauge wire and a direct alternator supply point, is required.

 

 

The key variables that determine which fuel pump is suitable for a particular engine combination are:

· Engine flywheel horsepower.

· Engine fuel efficiency, commonly referred to as BSFC or Brake Specific Fuel Consumption.

· Maximum fuel system pressure and the pumps flow volume at that pressure.

· Available voltage at the pump under engine load and the pumps flow volume at that voltage.

 

The problem coldsubycz is having, I know as I have the same set up, is the pump is not FLOWING enough due to the low voltage it is running at.

 

I had the same exact problem. Fuel pressure was good but as soon as we applied more VOLTAGE to the pump like it TELLS YOU TO DO IN THE FUEL PUMP INSTRUCTIONS my Duty Cylcle at the injectors went down because I was flowing more fuel.

Edited August 1, 2012 by Scooby2.5

[Scooby2.5]

I didn't mean to make people get upset. For that I truly apologize. This thread has been extremely informative and helpful and the time that others especially Scooby2.5 have put into this is invaluable. I have read the entire thread many times and fully understand what is going on. After reading my post where I measured the voltage I should have been clearer, I apologize for that.

 

All of my voltage readings are from a completely stock system. I did this so I would have a baseline reading to compare too. I was trying to give Scooby2.5 some more research info for this thread. It seems a good majority of GT's are giving 11.7 volts or so to the FPCM. For some reason my 05 GT is giving 13.4v to the FPCM with 14.5v at the battery while idling. I will do a test at the pump on startup. I had to hold the probes in the fuel pump harness so at the time I was physically unable to do start up test (my wife was with the kids so she was unable to help at the time).

 

For me what was interesting was even though my battery output was 14.5v my harness lost 1v to the FPCM. And even though I tested the pump at idle I lost 0.8v to the pump from the FPCM (7.83v output at the FPCM - 7.00v at the fuel pump. So my pump is seeing 12.7v, 1v less then optimum according to DW65c specs.

 

When I finish the wiring (which might be awhile since I'm a father of a 2 year old and 4 year old so time is limited) I will report my findings.

 

Thanks for posting the STOCK fuel pump voltage numbers that is in fact helpful, Sorry I didn't know you hadn't already rewired.

 

You actually have a much better voltage at the module then me or others have had.

 

My alternator only puts out about 13.8 volts so that could be part of the difference I was seeing.

 

Basically what you will need cold is AT LEAST 13.5 volts at the pump when you are all done. That will give you the best FLOW RATE because that is what the pump specs say the best flow rate is at that voltage.

 

http://www.horsepowerfreaks.com/images/products/aeromotive/340HP_Fuel_Pump_Flow_Chart.jpg

[Scooby2.5]

When I finish up my FPCM wiring project I will have my tuner/shop truly test the fuel pressure with a gauge.

 

When my tuner mentioned that he could not get much hp over my pump tune I was a little confused because even if my car was not outputting full 13.5v, even if it was 2v lower I should have still made a little more hp. Even though Scooby2.5's system was not full voltage a few years ago he was still getting a lot more hp over his pump tune. Not sure if I'm liking my tuner anymore. I'd really like to go down to Cobb, but that is so far away for me right now in my life.

 

I'll get this wiring done first, schedule up for a tune AND troubleshooting and see where that takes me.

 

I thank ALL of you guys for your help. I'm still amazed at how smart you guys are.

 

You would have to look at all the variables Cold, Like FMIC, dyno temperature, fuel, timing etc.

 

Dont sweat it too much on the numbers. If you get the proper voltage to the pump you should be flowing enough fuel at stock pressure to put down the numbers Calvin did with my car and Tim Bailey did with numerous other AVO380s