Fuel pump control module

One should not go placing a diode into anything without knowing the type, current rating and orientation of it in the circuit. Are we talking a zener, or a normal diode type? Were one is working in breakdown and dropping the 1.5V going to the sensor and thus making the circuit boost voltage to compensate, (because the voltage is rectified already), or are we modifying a portion of the AC that is being fed to the sensor circuit with a regular diode? Enquiring minds want to know.....

Ok if you want to talk about a diode in the alternator wire take it over to NASIOC where there is a long thread about this......

One should not go placing a diode into anything without knowing the type, current rating and orientation of it in the circuit. Are we talking a zener, or a normal diode type? Were one is working in breakdown and dropping the 1.5V going to the sensor and thus making the circuit boost voltage to compensate, (because the voltage is rectified already), or are we modifying a portion of the AC that is being fed to the sensor circuit with a regular diode? Enquiring minds want to know.....

 

Here you go Einstein

 

http://www.scoobymods.com/showthread.php/raise-your-alternator-voltage-10547.html?amp;

Lmao

 

Sent from my Galaxy Nexus using Tapatalk 2

Here you go Einstein

 

http://www.scoobymods.com/showthread.php/raise-your-alternator-voltage-10547.html?amp;

 

Any by the way for those interested:

 

http://www.ebay.com/sch/hkbelect/m.html?item=220813262467&clk_rvr_id=249453302475&afsrc=1&rt=nc&_trksid=p2047675.l2562

:icon_lol:Lmao..., ops. I sware not to talk about anything that relates to the "fuel-pump-control-module" ever, ever again on the "fuel-pump-control-module forum. I'll just sit and read everyone else talk about amps, volts, pulse width, what wire to use, buy somebody else's module because you can't really run a real pump without it, and so forth and so on......,

 

"Here you go Einstein

 

http://www.scoobymods.com/showthread...10547.html?amp;"

 

It is BubbleHead or Squid, eg. "Here you go BubbleHead", Mr. KCWagon. I do however appreciate the levity.

Unless you are twelve years old, you don't have to refer to me as MR. Kcwagon.

 

There has been a great deal of discussion and actual implementation of fuel pump control modifications. If you indeed have a good idea, then implementing your idea and reporting the results would be the most helpful to the forum. A long-winded theorization only adds to the confusion.

If you indeed have a good idea, then implementing your idea and reporting the results would be the most helpful to the forum. A long-winded theorization only adds to the confusion.

 

Mr. KCwagon just summed up all forum knowledge. Lots of very smart engineers on here who would blue screen the second a realistic PIA car problem crossed their path. To do is to achieve a high state of being. To do is to learn, and to do is to know. Thank you for summing up my personal and career goals so simply and thoroughly.

Hi all

 

2004 audm liberty GT here (legacy).

 

I have been running a walbro 460lph in tank on my completely stock wiring (except the walbro e85 compliant pigtail plug) for about 2 months now. Was a pain to get in the cradle but ended up having to double o-ring.

 

I have also changed fuel pump duty cycle on my rom to 0, 75 and 100 percent only (removed low flow) - this was done in the hope of ensuring sufficient voltage for the required fuel flow at high load.

 

Running ID2000's, e70, Sard FPR, braided fuel lines in engine bay with y block. From the spec sheets, the walbro 460 will draw 19 amps at 90 psi when receiving 13.5v. I am looking to run max boost of 29 psi with base pressure of 45 with vacuum. Allowing for say 5psi system losses, this means i will see total fuel pressure of 80 psi.

 

So for headroom, i will design the system on the assumption of 90 psi max. I am looking to ensure between 13.5-13.8v at the pump, and therefore allow 25 amp current to be catered for in my system.

 

After being on the dyno yesterday, fuel pressure was dropping at 24psi above 6000rpm at full load, causing lean out.

 

Obvious that stock wiring cannot handle draw / load. So the pump needs to be hard wired.

 

Thanks to this thread I sourced the 2006 Sti fpc module, today

 

I am keen on retaining fpc modulation for two reasons in this order of importance:

 

1. The walbro 460 flows a crap load of fuel at base pressure which means idle is hard to maintain. I will change my rom back to stock 0,33,66 and 100 % duty cycle. By regulating duty cycle down to 33% at low load, this will help reduce the huge amount of flow this pump provides.

 

2. Heating of the fuel causing efficiency issues

 

I have now replaced the fpc module with the Sti one. No noticeable difference

 

After reading every post on this thread and most of the links posted, I would like some direction as to whether the following setup will be ok.

 

Please do not suggest running hard wired 100% of the time by bypassing the fpc - I am not interested in doing this unless absolutely necessary which I don't believe it will be at this stage.

 

Before i go into the proposed setup, what are people's thoughts on the double o-ring I mentioned above? I don't believe this in itself will be causing the pressure drop, as I'm sure the voltage issue is more important. However interested (after reading doccrowley's experience) to hear if maybe this is exacerbating the issue??

 

1. I am going to run a 10 ag wire from the battery to a 30amp relay.

 

2. Will use the fpc module output trigger wire to trigger the relay, then run 10 ag B+ output from the relay directly to the walbro 460. Earths will be new to the relay and not shared.

 

3. Upgrade negative trigger wiring from fpc to fuel pump to 10 ag wiring. I will be drilling two holes in the top fuel pump metal cover to run the 10 ag wires directly into the pigtail plug on the walbro 460, insulating them with rubber grommets on the tank cover. This way I can avoid stepping down the wiring to the stock plug.

 

Based on a few people's earlier findings on this thread, I was thinking to also upgrade the fpc module factory B+ wiring to 10 or 12 ag from the battery (a separate one to the relay wiring in point 1. Above ). My thinking here is upgrading voltage/ current handling of the fpc module will be a good thing as evidenced by the tests completed by Scooby2.5 and others in this thread.

 

Another way to do this is run say 8ag wire from the battery to a distribution block in the boot, then take my two power feeds from here to the fpc module and the new dedicatee 30 amp fuel pump relay.

 

Seeking opinions on this before I go out and complete it.

 

Thank you to all who have contributed

 

Mick

impressive sounding car! however i don't think you can use the square wave output of the fpcm to drive a relay, it is too high of a frequency.

 

you can run a heavy wire from batt (with an inline fuse near the batt connection) or from the switched green wire in the steering column back to the trunk to the new relay's pin 87. cut the existing fpcm supply wire (fpcm pin 10) and the harness side connects to relay pin 86. the fpcm side of the cut wire goes to relay pin 30. run relay pin 85 to chassis ground screw. all of that is just to get full power to the fpcm.

 

you can also replace the wires with heavier gauge going from fpcm to fuel pump, and from fpcm to ground.

Correct output wire of FPCM will not control relay as heiche said.

 

 

You have to do it like many others have said and the many drawings in this thread.

 

The wire from the stock Fuel pump relay is used to trigger the new relay.

 

dr20t Why change it from what the pump manufacturers recommend?

 

See wiring diagram posted in this thread from Aeromotive but just keep you FPCM in place.

 

If you dont think the FPCM (sti or otherwise) can handle the current then I would just purchase the DCCDpro.com FPCM and be done.

its a trick radio enthusiasts do to make their subs louder.

my car runs about 13.5 volts once warmed up. 1.2 volts could account for almost 10% more flow from a pump.

 

I just did this mod with the MK3 PTC diode fuse from Australia. They have been doing this for years on the japanese imports.

 

Notice he has added Subaru to the list as I ordered and installed one of these MK3 diode/PTC fuses.

 

 

http://www.hkbelect.com

 

If you email this guy he will give you a discount

 

 

Here is a thread on NASIOC and this will for sure help the fuel pump voltage issue, although wiring should still be changed etc.

 

http://forums.nasioc.com/forums/showthread.php?t=1602651

 

My alternator voltage is around 13.8 when warm. By the time the voltage drops through the circuits in the car I was low.

 

Now I am putting out 14.5 pretty much all the time.

 

I have a AGM braille battery which when fully charged should be 13.8 volts, 12.6 at rest.

 

It needs 14.5-14.7 to charge it properly according to braille. After doing this mod my battery is 13.84 when car shut off and 12.6-12.8 after resting. I am sure my pump is now running easily 13.5 volts.

Edited August 3, 2013 by Scooby2.5

Correct output wire of FPCM will not control relay as heiche said.

 

 

You have to do it like many others have said and the many drawings in this thread.

 

The wire from the stock Fuel pump relay is used to trigger the new relay.

 

dr20t Why change it from what the pump manufacturers recommend?

 

See wiring diagram posted in this thread from Aeromotive but just keep you FPCM in place.

 

If you dont think the FPCM (sti or otherwise) can handle the current then I would just purchase the DCCDpro.com FPCM and be done.

 

Thanks Scooby - I think I was vague in my initial post. Not really looking to change anything other than where the direct 10ag wiring from the battery will go.

 

That is, instead of going to the fpc module via a relay, it would instead go to the walbro via a relay.

 

I thought this is what you suggested a few pages back based on what zorro did on nasioc?

 

In any case not looking to reinvent the wheel at all

 

I am comfortable that the fpc can handle the current draw and don't believe the hype about it being "only rated to 8 amps otherwise it will attack your families and steal your clothes and the world is gonna end".

 

In the unfounded and unforeseen off-chance that this is true and the fpc module fails, then I would look at alternatives. But thanks to the work of your and others on here, I don't see evidence of it nearly 2 years on.

 

Another thought that just occurred to me -

 

What about if i run two separate circuits using 10ag wiring from the battery to the fpc on one relay, and the same for the walbro pump through another relay?

 

My logic here being upgrading wiring and voltage handling of both the fpc and the pump independently? And in this way ensuring both circuits are protected from voltage drop??

 

Thanks again for all input

 

Mick

the positive wire of the pump is switched from the key. so you can run a large wire from battery and use the positive wire going to the pump to turn on the relay and maintain stock function.

 

you would have to use a solid state relay that would allow you to keep the pwm. sothe solidtate relay wired to ground and then to the pump. the fuelpump control module to the relay. you will need a relay that is ment to ground froma ground signal. they are about 30$ here from automation direct.com

 

one of the things you spoke of about your idle issues wont be correctly remedied from having the pump running slower if you have very large injectors the minumum opening time can be to much for such a small motor. and the pump running at 33% will still be more flow than the the required fuel at idle. and i would not recomend running the pump slower than 33% as it may not like it. as it will always try to build the target pressure and its available torque will diminish.

Edited August 3, 2013 by frank_ster

Thanks frank

 

Gotcha - I think I referred to the wrong trigger wire in my first post (I now realize I need to use the power output side from the fpc to trigger the relay for the pump , correct?)

 

What about powering the fpc through direct wiring through a relay?

 

What are people's thoughts on this?

 

Should I run one 8ag wire from battery to boot (fused at the battery) to a distribution block, then two 10ag wires to power the fpc and fuel pump via two separate relays?

Thanks frank

 

Gotcha - I think I referred to the wrong trigger wire in my first post (I now realize I need to use the power output side from the fpc to trigger the relay for the pump , correct?)

 

What about powering the fpc through direct wiring through a relay?

 

What are people's thoughts on this?

 

Should I run one 8ag wire from battery to boot (fused at the battery) to a distribution block, then two 10ag wires to power the fpc and fuel pump via two separate relays?

 

You don't need a distribution block

Large wire from battery to relay then larger wire from that relay to the pump

That relay is signaled on by the existing positive wire

 

On the negative side large ground to solid state relay the. Large wire to negative of pump then that relay is signaled by the existing pump negative wire

So the new relay take on the load and no further mods would be needed

1. New wire From battery to new relay

2. Existing fuel pump relay wire, which used to feed the fuel pump control module now controls the new battery relay (turns new relay on and off with key on).

3. From the new relay large wire to the pump.

 

This will give you true battery voltage at the positive side of the pump......

 

 

The negative side wire that comes from the fuel pump control module to the pump needs to just be replaced with a larger wire, its the PWM signal.

 

Done.

 

Now you have direct battery voltage to the pump via the new relay and wire from the battery, controlled by your factory fuel pump relay (on off key signal).

 

You also have a large wire now going from the module to the pump on the "negative lead".

 

The negative out of the module is a changing voltage leg (ground) depending on what the ECU asks for. 33, 66, 100. All the module does is change the ground reference.

 

At 100 percent the module outputs basically 0, at 66 percent it is approx 12 and at 33 percent it is approx 7.

 

That way the difference between 13.5 to "ground" 0,7, or 12 is what determines the potential difference at the pump and drives the pump at the different speeds.

 

see post 127 and 131.

 

Only difference is the negative lead to the pump should be coming off the module instead of just straight to ground which gives you the varying speed at the pump.

Edited August 4, 2013 by Scooby2.5

My plan now is to wire it like z0rr0 did. I purchased the DW wiring kit, just to get the inline fuse, 12 ga wire, and relay and relay socket. Just to make it a more finished product. (IM OCD)

 

Im going to run the DW kit from the battery to the pump positive lead. Switching the relay as we have been off the fuel pump relay feed to the module.

 

Im going to leave the FPCM in place which is feeding the varying voltage to the negative pump lead.

 

Should have full voltage direct to the pump from battery and varying negative lead from the module which should duty cycle the pump just like factory.

 

At least going this route you will always have the batt/alt voltage to the pump and dont have to worry about a drop going through the wiring or the module.

 

The negative lead out of the module to the pump seems to approximately be 0, 8v or 6v depending on the duty cycle requested.

 

Will report back on how it works out. We will be doing mine and kcwagons car this way in the near future.

Ok KCwagon and I worked on his car today and got no where.

 

We did find that the PWM signal on the FPCM is switching the ground reference voltage from 0 to various voltages to get the 10v for 67% and 8v to get 33%.

 

So what is happening is you are feeding say 14v to the pump and the negative lead from the module to the pump is changing voltage.

 

More reading.......

 

http://forums.nasioc.com/forums/show....php?t=2308392

 

In the thread KC Wagon posted above (359) read posts 7, 10, 17, 20 Most of them by Z0rr0

 

He wired direct battery voltage to the pump and then left the module negative side from the module to the pump alone.

 

This would provide full voltage to the pump and allow the module to just change the negative reverence point from 0 to 4 to 6 giving you a difference of 14 for 100%, 10 for 67%, 6 for 33% for the different duty cycles. (approx voltage numbers)

 

His car has been running fine.

 

After the low voltage discovery on my car Calvin from Cobb and myself wired it the way we did but probably shouldnt have.

 

Looks like the stock FPCM would work fine the way Z0rr0 has done it.

 

This way you are not trying to push HIGHER voltage THROUGH the FPCM. Although the STI wiring is larger so sends higher voltage to the module from the fuel pump relay

 

And the only thing changing is the lower voltage on the negative side from the module

 

 

I put in a call to him already and will report back after we chat about it.

Thanks sooby - again apologies for any confusion caused.

 

I actually thought you were looking to change the setup on kc's wagon after your initial findings (max of 13.2v at the pump if I recall correctly)

 

Will proceed with the install using the above setup tomorrow and report back with findings

 

Mick

Ok one more question - if I'm using the factory power wire (that originally powered the fpc module) to now switch the new fuel pump relay, how is the fpc module receiving any power?

 

Does it not need positive power in order to still regulate pwm through the fpc negative output wire to the negative side of the fuel pump?

 

This is the only missing piece of the puzzle for me.

take it after the fpcm on its way to the pump.

take it after the fpcm on its way to the pump.

 

Which is what I was intending on doing until I saw scoooby's post above, advising to use the original power wire from factory fuel pump relay that would normally go to the fpc, as the trigger wire for my new relay

well it goes through.. you can interupt the wire from the relay to fpcm or just use it after it would give the same result.

Like Frank said, just feed the batt voltage from the new relay to the pump and to the FPCM.

 

If you want to try it you could just feed the FPCM and then replace both wires from the FPCM to the pump with larger wire and see what you get.

 

I think if your initial voltage from the battery is good then you should get at least 13.5 if not more to the pump from the STI module.

 

We didn't mess with KCs anymore but he did at some point have to change his alternator out and it puts out 14.2 so his could be at 13.5 now but don't know.

 

Don't forget we were using a meter so the readings we were getting could have been off since that neg leg is PWM.

 

If I remember correctly if we measured his positive leg in reference to true ground he was getting more.

 

The PWM neg leg can give you weird averaged readings so as others said best to use a scope.

 

 

When I re-do mine I am first going to increase wire gauge both pos and neg from module to pump and see if mine is at or above 13.5. If it is I am going to keep it that way.

 

If not I will wire from new relay straight to pump on pos side and just use larger wire on neg side like I suggested above.

 

Don't forget Franks suggestion of the alternator mod.

 

Subaru alternator voltage is notoriously low, so none of this helps too much if your alt is only putting out 13.5-13.8 in the first place.

 

The goal here is to have 13.5-13.8 at the pump and with voltage drops etc the alt needs to be putting out more to begin with

Edited August 4, 2013 by Scooby2.5