Fuel pump control module

[dr20t]

Ok so wiring all done and cleaned up

 

Consisting of:

 

10ag wiring fused at the battery, direct to 4 pin, 30 amp relay pin 30 mounted in the boot (trunk for you USA folk )

 

10ag earth wiring to relay pin 85

 

12 ag trigger feed from fuel pump control module red and black wire to relay pin 87

 

10 ag power wire from relay pin 86 to positive side of fuel pump

 

10ag wire from fpcm negative output to negative wire on fuel pump

 

Measured 13.94v at 'key on' and engine idle

 

This was also before I installed the voltage booster fuse / diode referred to above by Scooby2.5

 

Haven't tested voltage after the voltage booster install but assuming a 0.5v increased I would say pump voltage is now at 14.4v which is fantastic

 

Going back for retune on 22nd August so hopefully this problem is now sorted

 

Thanks again to all for your assistance

 

Mick

[frank_ster]

check the voltage when the engine is warm. the ecm tells the alternator to raise the voltage when cold to about 13.8 volts. but then settles down to 13.2

[dr20t]

Should've clarified that was warm

[sphen22]

Cobb Tuning Socal just recommended this as a fix for the low voltage problem

 

http://www.kipanderson.net/rs/hobbs.htm

 

Anyone have any experience with such an animal? Seems like a good idea as it only will come on above 10psi if set to.

[Scooby2.5]

Cobb Tuning Socal just recommended this as a fix for the low voltage problem

 

http://www.kipanderson.net/rs/hobbs.htm

 

Anyone have any experience with such an animal? Seems like a good idea as it only will come on above 10psi if set to.

 

That is some sort of wastegate pressure switch?????

What does that have to do with fuel pump voltage?

[sphen22]

Oh sorry, not using the switch for the application on the web page but instead using it in parallel with the oem fuel pump wiring, with the switch activating a direct battery current to the Fuel Pump when above 10 psi when the pump is already at 100%. This way during idle and cruise it would still get the staggered voltage from the FPC.

[Scooby2.5]

Good luck with that and tell us how it works when you get done.

[sphen22]

Will do

[frank_ster]

^ well you can send direct power to the pump and still have variable speed. because the variable speed is controlled on the negative side.

[KCwagon]

Good luck with that and tell us how it works when you get done.

 

Will do

 

He is being sarcastic. Like Frankster said...Modulation is controlled via the negative side of the circuit. I am not sure what purpose it would serve to run another positive lead. You can wire the car to run full battery voltage and still retain your Fuel Pump Duty cycles. (w/o buying a Hobbs switch) It took several of us about a year to figure it out. The information is actually in this thread.

 

But I, on the other hand, would REALLY like to know how it works when you get it done.

 

Did you read the thread ?

[sphen22]

Read through a lot of it but must have missed the negative side controlling modulation. Why isn't this moved to the op. Instead of having to read through all the pages.

 

So all I need to do is run a lower gauge wire directly to the fuel pump then through a relay.

 

Then lower the gauge on the module to pump for negative terminal.

 

Do you run the old high gauge positive from the module into the new low gauge from the relay, splicing it just before the pump?

Edited August 29, 2013 by sphen22

[KCwagon]

Read through a lot of it but must have missed the negative side controlling modulation. Why isn't this moved to the op. Instead of having to read through all the pages.

 

So all I need to do is run a lower gauge wire directly to the fuel pump then through a relay.

 

Then lower the gauge on the module to pump for negative terminal.

 

Do you run the old high gauge positive from the module into the new low gauge from the relay, splicing it just before the pump?

 

I'll try to make it simple if I can.

 

*) 12g + wire from battery to a relay

*) 12g + wire from relay to pump

*) 12g - wire from pump to Control Module

*) Use the original factory power wire that runs to the FPCM (control module), splice, and feed both the 1) FPC module and 2) the relay.... As a result you will have battery power running to the pump, a relay that turns on that power, a fpcm that is functional because it is powered, and the retention of the Negative side modulation. You will also terminate the original Fuel Pump power wire coming out of the FPCM.

 

Hope this makes sense. I am seeing about 13.6-13.8 volts at the pump (100% fp duty cycle) while retaining the factory modulation of the fuel pump.

Edited August 30, 2013 by KCwagon

[sphen22]

I'll try to make it simple if I can.

 

*) 12g + wire from battery to a relay

*) 12g + wire from relay to pump

*) 12g - wire from pump to Control Module

*) Use the original factory power wire that runs to the FPCM (control module), splice, and feed both the 1) FPC module and 2) the relay.... As a result you will have battery power running to the pump, a relay that turns on that power, a fpcm that is functional because it is powered, and the retention of the Negative side modulation. You will also terminate the original Fuel Pump power wire coming out of the FPCM.

 

Hope this makes sense. I am seeing about 13.6-13.8 volts at the pump (100% fp duty cycle) while retaining the factory modulation of the fuel pump.

 

Beautiful! Thank you.

[coldsubycz]

I'm the guy from (Page 13, Post# 192). A lot has happened/been discussed over the past year since I've done the "original" mod.

 

So like I've said been running my setup for 1 year now with a DW65c/STI FPCM with no problems. Mine is running full power THRU the FPCM. So after reading the rest of this thread I should change my setup to gain direct voltage to the pump AND prevent the FPCM from burning out? Is that correct? OR should I just leave it alone?

 

I wouldn't need to retune after doing this, would I?

Edited August 30, 2013 by coldsubycz
additional question

[doccrowley]

Thank you for the simple summary!

[KCwagon]

I'm the guy from (Page 13, Post# 192). A lot has happened/been discussed over the past year since I've done the "original" mod.

 

So like I've said been running my setup for 1 year now with a DW65c/STI FPCM with no problems. Mine is running full power THRU the FPCM. So after reading the rest of this thread I should change my setup to gain direct voltage to the pump AND prevent the FPCM from burning out? Is that correct? OR should I just leave it alone?

 

I wouldn't need to retune after doing this, would I?

 

Your set-up is likely just fine with the 65c. I believe the issue of amperage draw and FPCM could be a concern with larger fuel pumps. I DID see a significant improvement in voltage when I ran battery power to the pump. No need for a re-tune.

 

Before I started messing with mine, I was seeing about 11.6 volts to the fuel pump at 100% duty cycle. As I started changing things, Scooby2.5 and I measured the differences in configurations. Here is a brief synopsis:

 

All measurements are at start-up w/ 100% Fuel Pump Duty Cycle

 

11.6 volts - 100% factory wiring,stock FPCM, DW 65c

11.8 volts - 100% factory wiring,STI FPCM, DW 65c

12.6 volts - Upgraded wiring, utilizing the STI FPCM, DW65c

13.8 volts - Upgraded wiring, battery power to pump, DW 65c

[frank_ster]

^ so the sti fpcm is the least effective ?

 

if all the mods were done to the stock one would there be 13.6 volts to the pump ?

[Turkeylord]

Thanks KCwagon, Scooby2.5 and Frank_ster for your helpful posts in this thread! Bren isn't happy with my DW65c, so I think I'm going to try this before switching to something bigger.

 

 

Now that we understand the system better, has anyone tried the wiring upgrade with the OEM FPCM?

 

 

My other thought was that this might even be enough with the OEM pump for those borderline situations like a 16g on gas...

[frank_ster]

^ i would try that first .. run the bigger wires to the pump as mentioned. .. if that still is not good enough plug in the sti fpcm. you wont be doing any duplicate work.

[Scooby2.5]

I'm the guy from (Page 13, Post# 192). A lot has happened/been discussed over the past year since I've done the "original" mod.

 

So like I've said been running my setup for 1 year now with a DW65c/STI FPCM with no problems. Mine is running full power THRU the FPCM. So after reading the rest of this thread I should change my setup to gain direct voltage to the pump AND prevent the FPCM from burning out? Is that correct? OR should I just leave it alone?

 

I wouldn't need to retune after doing this, would I?

 

I would leave it alone. Two ways of doing it are direct positive relayed feed to the pump, larger neg wire from module to pump.

 

Larger wire FEEDING MODULE and larger pos and neg wires to the pump from the module

 

I personally think the STI module can handle it so I would leave it alone.

 

You might double check the voltage coming out to see if anything has changed over last year or so

 

Mine doesn't have larger wire and its been fine but I am getting ready to change it

[coldsubycz]

^ so the sti fpcm is the least effective ?

 

if all the mods were done to the stock one would there be 13.6 volts to the pump ?

 

 

The STI fpcm is "better" than the Legacy fpcm. If you just swap the Legacy fpcm to the STI fpcm there is a "slight" increase in voltage if everything is left stock. Upgrading the wiring and running power from the battery and either running it thru the new STI fpcm or direct to the pump is the only way to up the voltage.

 

I upgraded all my wiring to 10g and used a new relay to run power thru the "new" STI fpcm. But that was soooooo last year . If I was running a larger pump than the DW65c I'd run the wiring like the guys are doing now. If I have time today I'm going to draw out the new wiring to compare with the way I did it.

[coldsubycz]

Thanks KCwagon, Scooby2.5 and Frank_ster for your helpful posts in this thread! Bren isn't happy with my DW65c, so I think I'm going to try this before switching to something bigger.

 

 

Now that we understand the system better, has anyone tried the wiring upgrade with the OEM FPCM?

 

 

My other thought was that this might even be enough with the OEM pump for those borderline situations like a 16g on gas...

 

 

I have the same pump that you do. My tuner said the same thing that yours did. My tuner said that my system was running fine, but it seemed that the pump was not "giving it's all". I did the upgraded wiring, albeit last years design and all my fueling issues on e85 went away.

[coldsubycz]

The diode trick works great, and the MK3 fuse with diode I posted works GREAT and is factory like. Its a bit expensive but by the time you purchase the wire if you dont have any, and make one up like others have done to plug into the fuse block its worth it I think, but I am OCD a bit...LOL

 

 

Just so I can clear this up in my head: You used this MK3 fuse and installed that "plug-n-play" in the fuse box under the hood instead of cutting the wire up by the alternator and installing a diode?

 

If my thinking is correct, which fuse did you replace in the fuse box? (I'm sure I can figure it out, just being lazy, but also want to verify! )

 

Thanks again for all this work!

[Scooby2.5]

^ so the sti fpcm is the least effective ?

 

if all the mods were done to the stock one would there be 13.6 volts to the pump ?

 

Go back to my research early on when I was at Cobb fixing this in the parking lot. LOL

 

I'm pretty sure if I remember correctly even if you powered the stock module direct it was still dropping voltage. I think about 1 volt

 

I originally wanted to change the size of the fee wire from the stock fuel pump relay (feed) and leave the rest stock but it still wasn't enough to get it above the 13.5 threshold needed for aftermarket pumps.

 

I posted all the results when I got back from Cobb its probably in the first 3-4 pages

[Scooby2.5]

Just so I can clear this up in my head: You used this MK3 fuse and installed that "plug-n-play" in the fuse box under the hood instead of cutting the wire up by the alternator and installing a diode?

 

If my thinking is correct, which fuse did you replace in the fuse box? (I'm sure I can figure it out, just being lazy, but also want to verify! )

 

Thanks again for all this work!

 

Yes

 

The alt sensing fuse. Look at your fuse box lid it will tell you