Fuel pump upgrade & wiring 12v

[isnms]

edit: Added a pretty convincing pro



I have been running a good tune lately, so I was contemplating putting it on a dyno. I don’t run it at 14psi all the time, mainly 8psi, but I would on the dyno.

[thumb]http://www.supramania.com/forums/attachment.php?attachmentid=23379&d=1217030628[/thumb]

As I was trying to determine that everything was set to put it on a dyno, I kept coming back to my two ‘have/waiting installation’ items: mkiv tt fuel pump and aeromotive afpr. Then I started thinking that I had read the stock fuel pump was only good to about 14psi of boost. So I started searching. The results indicate that the stock fuel pump is only reliable to stock boost :aigo:

Joe: Responses from the SF version of this thread...

I've personally seen 2 cars that dropped fuel pressure while into boost with a 57 trim ct-26, and the other with a ts04.

The stock pump is ONLY good for the stock turbo.

if anyone has ever monitored a stock pump under full throttle, red line boost. then you'll see a 20psi pressure drop from any stock pump. including the 2jztt pumps. they push 50-60psi (depending on if you have the aeromotive regulator), then drops to 45psi, then 40psi at 7200rpm. that scarry yo!

my dumb ass blew two headgaskets due to an old failing stock fuel pump....a walbro is only ~100 bucks.

with that said, replacing the fuel pump is one of the first things i do now.

I'll be upgrading my pump before driving it.

Collin

I have witnessed a few guys run 340 and another at 350 RWHP but the pump was MAXED out. I would say to be safe > 300 and change at most.

Duane

Seems I am at the razors edge with my current tune and setup. So I will install my pump before dyno and try to up the boost. BUT, now the question comes up of voltage to run. The information on this is varied.

Some pro of 12 volt mod:
• easier to tune
• walbro does not work at low volt
• mkiv pump draws more amps, so best to run larger wire
• the .7 ohm resister will drop to much voltage making the mkiv pump bog
• with modifications - the calibration of the ecu switch point is off
• predectable fuel delivery characteristics (no stumble).

• This site - Road Race Engineering – Fuel pump flow rates. -
indicates the mkiv tt fuel pump can draw up to 21 amps.
The stock fuel pump circuitry runs through the 15A EFI fuse.​

and more

Some cons of 12 volt mod:
• decrease pump life
• walbro is rated for 7v-14v
• heat up fuel witch lead to increased evaporative emissions
• decreases gas mileage
• stock wiring and functionality is just fine
• unnecessary
and more

also

Automotive OEM’s and racers know that excessive fuel circulation at idle and low engine load causes heating of the fuel, loss of engine power, and more fuel loss due to evaporation/vaporization, and none of these are beneficial…

I have three plans of running new wire to the pump. First two keep the relays/relay in the engine bay.

1. One keeps the low volt option but I need to know the correct resistor to use if the stock resistor is going to make the pump bog down
[thumb]http://i80.photobucket.com/albums/j187/isnms/Supra/fuelpumprelay.gif[/thumb]
2. Another is straight 12 volt.
[thumb]http://i80.photobucket.com/albums/j187/isnms/Supra/fuelpump_single_relay.gif[/thumb]
3. Last just jumper pin 2&3 of fuel pump control relay connector and run fused 10awg to rear, install relay there. (basically shaeff’s write up)
[thumb]http://i80.photobucket.com/albums/j187/isnms/Supra/fuelpump_single_relay_rear.gif[/thumb]​

So with all that said; Help me plan my wiring.
• leave stock circuitry
• run 12 volt full time, upgraded wiring
• run upgraded wiring with hi/lo switching still in place. resistor size?

Note: I have both the walbro and mkiv pumps. I prefer to use the mkiv for Toyota quality/reliability.
Thanks for your input.

---

​

Just wanted to update with the configuration I'm going with:
I'm going to go with this relay adam directed me to:

this is the relay I used:
http://www.bmotorsports.com/shop/product_info.php/cPath/150/products_id/504
it seems to be the most robust, and no soldering was required.

and keep it in the engine bay then just run a 10awg wire to the pump:
the 'Y' for pin 2&3 is to retain the ability to jumper FP and +B in the diag connector.

[thumb]http://i80.photobucket.com/albums/j187/isnms/Supra/fuelpumt_singlerelay_enginebay.gif[/thumb]​

 

[suprahooked]

I dont know if this helps but i run the a1000 fuel pump. I let the stock wire trigger the 30 amp relay that runs the pump. What i diid was run a 10 guage fused wire to the relay and let the stock wire turn on the relay. You could do the same with any pump. John

 

[isnms]

That's a rout I have heard about but not explored. An external pump.
Is it recommended to run the a1000 at 12v full time?
Do you experience any of the issues listed, like:

Automotive OEM’s and racers know that excessive fuel circulation at idle and low engine load causes heating of the fuel, loss of engine power,...

 

[isnms]

Where is all the input from the folks that say "if you upgrade the pump you must run 12v" and the people that say "changing the stock circuitry is not needed"?
Looking for input. I don't want to do this wrong.

 

[jdub]

This is what I posted in Mario's fuel pump thread...esentially what you have in diagram #2 above:

The 12V relay in the back essentially replaces the stock FP relay. Walbro pumps pull a bit more current...the stock wiring (assuming good condition) can handle it, but using 10GA battery power is is much better, especially if you have the battery in the back. Power to the pump travels a shorter distance.

Grounding FC (taking FC away from ECU control) is a bad idea. The ECU uses the CPS Ne signal to determine if the motor is running and grounds FC internally. If the motor suddenly stops (i.e. a wreck), fuel pump operation is terminated to alleviate a fire hazard. Power to the stock pump comes from the circuit opening relay...it has inputs from STA at the ECU to control the stock pump on engine start. You want to keep this relay.

In your case, you want to use the stock wiring to actuate the new 30A relay, using the power from the circuit opening relay...FC controls the circuit opening relay per above. Connecting B+ and FP is correct, but it has to be FP to the pump, not from the ECU (yellow wire).

In my '89 TEWD:
+B = Blue wire w/ black stripe
FP (to pump) = Black wire w/ red stripe...pretty sure this is your black w/ red rings wire...confirm by looking at the one going into the tank.

All you have to do is jump or connect these two wires on the harness side of the fuel pump relay connector...you can remove the relay and the resistor. You now have a ECU controlled wire to the rear to actuate your new 30A relay, for normal operation and engine start...call it FP if you like

The by pass of the fuel resistor mod is the only thing most people need to do when installing a walbro to get the 12v.

And that's pretty easy too...just jump the two wires on harness side connector to the resistor. Use at least a 12GA wire. The pump will always run at 12V

Something to look at is a Weldon Fuel Pump Controller:

http://www.weldonracing.com/product.phtml?p=23

The 14000 Controller is an PWM electrical device that can control the speed of a Weldon Fuel Pump to achieve lower flow (gph), but allows fuel pressure to remain constant. It also allows the user to “toggle” between this lower pump speed and full pump speed as increased vehicle performance is required. The 14000 Controller actually “spreads” out the current that the motor receives, this is what “slows” pump speed.

It allows you to do essentially the same thing as the resistor...problem is these are kinda pricey. I'm just starting to look at one of these, but you might be able to use FP from the ECU to effect the "toggle" from low to high speed. On an AEM or Motec, I know you can.

 

[isnms]

jdub - That 14000 looks interesting. I'd be interested if you can make it work using the TCCS. I'm afraid it may be beyond me.


My third diagram is the one that shows connecting +B and FP and having the relay in the rear. I drew some boundaries to try to show where I have the components.

...the stock wiring (assuming good condition) can handle it...

What is the test to determine if stock wiring is adequate? I want to use the mkiv pump which seems to draws more amps than the walbro.

But doing this makes it 12v full time. This is the issue I want to resolve before I do the wiring.



edit: I thought I has seen something like that 14000 running with AEM. The guy on the http://www.lextreme.com/Lexus_Toyota_V8_AEM.html site has AEM running with a Kenne Bell boost a pump and a solid state relay. And looks like $100 less. pn# KB89069

 

[jdub]

It's going to depend if the Weldon controller can be switched using ground or not. If so, you could run FP from the ECU to the controller. Even if it requires +12V to switch, that can be gotten around by running a relay to it providing 12V switched by ground from FP to the relay. The big problem is the switch over point programmed in the stock ECU...the whole idea is to provide 12V to the pump when you need it. With a big turbo, that may need to be sooner than later than what the stock ECU does (one of the "pros" you listed above)

JJ may correct me, but the longer the wire, the greater the resistance for a given length for a specified current draw. The stock wiring travels from the EFI fuse, to the circuit opening relay, through the wire from the front to the rear of the car...a ~10' run. Each step adds resistance to the circuit.

One of the best reasons to rewire the fuel pump is to decrease this resistance in an effort to eliminate the chance of voltage drop at the pump. Running a 10GA wire direct from the battery (fused) avoiding the convoluted path the stock wiring takes reduces overall resistance in the circuit...especially true if the wiring from the front to rear is not in the best of shape after 20 years or so. Using the stock wiring to trigger a relay is fine though and the distance between that relay to the pump is short if the relay is in the rear of the car.

Increased current draw from a larger pump or dual pumps, makes this even more of a good idea...in addition to the other "pros" you mentioned. Having the battery in the rear (very short route to the pump) makes this a no brainer for me

Interesting link BTW - gonna have to look into that.

 

[isnms]

It seems the KB89069 is activated by an included pressure. Wouldn't that eliminate needing the TCCS to do the switching?

Kenne Bell 40 AMP Boost-A-Pump (Supercharged)
$250.00
Model: KB89069
• Activation vacuum or pressure switch included in kit.

Kenne Bell Boost-A-Pump 20 amp
for Vehicles with Supercharger / Turbo
pn# KB89067
$229.95​

http://www.mustangpartstech.com/GeneralInformation/KenneBellBAP.html <-- instructions


http://www.kennebell.net/accessories/boostapump/boostapump.htm

 

[jdub]

From reading some of the documentation, the unit would activate at 3 psi boost....yes, that would take the TCCS out of the loop. The question I couldn't answer concerns scale...what voltage does it supply to the pump (and pressure to the rail) prior to activation? I assume the included controller would allow you to scale beginning at that point.

Personally, I would opt for the 40A unit...20A is a bit to close and I would like the overhead for when this thing scales voltage output up.

I read the AEM Lexus mod link...Thank you! I'm planning to use an AEM on my next motor and that looks like a very good way for me to control pump output (my AEM has the same PW out at 9c).

 

[jtran8]

I've been running mkiv fuel pump for over a year now and never have any probplem . I followed " Shaeff " how to 12v rewiring thread in tech-tip , i also removed fuel pump relay and fuel pump resistor .

 

[isnms]

jdub - I don't really want to side track this thread but I have a question about that guys AEM wiring. Why is he using the output from the BAP to feed a SSR? From the BAP information, it seems the BAP should power the fuel pump.

jtran8 - no heating of fuel, decreased gas mileage, increased evaporative emissions?

 

[jdub]

You know, I'm scratching my head as well on that one. I'm looking through a bunch of threads on the AEM forum in an attempt to reconcile this.

 

[isnms]

Only other things I find are on post #3 here - http://www.lextreme.com/forums/showthread.php?t=9660

and this in the archives:

cribbj07-08-2007, 03:26 AM
I use one of those with my Supra fuel system and like it a lot. I helped Jeff Lucius from the VR4 crowd do some fuel pump testing a few years ago, and it's simply amazing how sensitive most fuel pumps are to the system voltage.

I won't repost the article, but here's a link to it: http://www.stealth316.com/2-fuelpumpguide.htm The whole article is great, but if you're only curious about the Denso pumps, click on that tab and you'll find my tests.

So I use the Kenne Bell Boost-a-Pump in conjunction with a big solid state relay, and a PWM circuit generated by my AEM ECU, and I have three different voltages that are fed to my fuel pump:

8.5-9 volts for idle and low load cruising
12 volts for acceleration and low boost
16 volts for high boost

Works like a charm, and it avoids excessive circulation of fuel which is unnecessary and only heats it up.

 

[figgie]

the weldon 14000 controller. It is a basic PWM modulator, Frequency is static but the duty cycle is adjustable. In this particular circuit, it goes from about 20&#37;- 80% max for the 14000 controller.

There are some DIY PWM circuits that can handle fuel pump control without any issues and they are vrmin-100% (vrmin = Variable Minimum). I actually use that same circuit for LED dimming control.

Why PWM you might ask? Well take a look at the size of the fuel pump resistor. It is that big for a reason. Disipate HEAT. PWM is extremly efficent. Usually in the magnitude of 90+% due to the heat generation being small compared to inline resistor.

The other thing about PWM.

The voltage out is what ever the voltage in. So if it is running at 13.8. That is what the motor will see. Very important at low DC as most resistive based speed control will not enable the motor to start. PWM allows for the motor to see the full voltage but you are basically limiting the current

 

[jdub]

Thanks figgie
On the previous page there's a Lexus write-up using a Kinne BAP and Solid State Relay...why the SSR? The BAP varies voltage, but it looks like he's controlling the SSR with an AEM.

 

[figgie]

Thanks figgie
On the previous page there's a Lexus write-up using a Kinne BAP and Solid State Relay...why the SSR? The BAP varies voltage, but it looks like he's controlling the SSR with an AEM.

Ok, looking at the lextreme thread. The post cribbj is clueless. PWM = 9v? He is dead wrong. Again PWM is current controlling not voltage. What I guarantee you he is doing, putting a multimeter on the output. The mulitmeter will RMS the voltage signal, it will deciper the 13.8v @ 60&#37; DC to be around 9v. The true signal when put under an O-Scope will be the full 13.8v but it will look like a square wave. Think of PWM as a Square wave generator without a negative portion of the wave He said he is running the PWM from the AEM. I know for a fact the AEM can not output that much current from the outputs so what is he using as the current gate? A mosfet or a solid state relay? You mentioned SSR but I do not see that in his post?


As for his system. So much complexity for nothing really. If he ran the 16v all the time and PWM that via a solid state relay. Then he can PWM from 5% to whatever the max on his controller is and not have ALL that complexity or silly logic behind it.


Voltage control works well as long as the voltage is not below the motor's threshold. Usually not an issue unless you are running the motor really really slow. For walbro might no be an issue but for big single fuel pumps, the slower the better

 

[jdub]

This was at the top of the write-up:

My setup consists of the AEM, a single Supra fuel pump, a Kenne Bell Boost-a-Pump, and the OEM FP ECU has been replaced by a simple SSR (Solid State Relay).

Followed later...he is using a SSR:

Because my car was originally a GE (non turbo) car, I did not have a separate EFI #2 relay, nor a separate circuit for the fuel pump, so I ran a separate 30a fused, #10 wire to the hatch of the car, and installed a 75a heavy duty Bosch relay which is triggered by the EFI #1 relay signal from the old FP ECU harness connector. The output of the Bosch relay goes to the Kenne Bell BAP, the output of the BAP feeds the SSR, and the output of the SSR feeds the fuel pump. I also have the AEM setup with LS8 triggering a relay to give the BAP a signal to increase its voltage to 16v whenever boost is 15psi, engine rpm is 3000, etc.

You'll have to forgive me figgie, but I'm just starting to grasp how PWM works. I understand the theory, but the details on implementation seem to elude me :3d_frown:

 

[isnms]

I'm interested to know if this can be implemented with the TCCS (and how to) or does it require going stand alone (AEM)?

 

[figgie]

This was at the top of the write-up:


Followed later...he is using a SSR:


You'll have to forgive me figgie, but I'm just starting to grasp how PWM works. I understand the theory, but the details on implementation seem to elude me :3d_frown:

jdub

no problem

let me show you how I learned

http://www.cpemma.co.uk/pwm.html

That site is where I got my PWM circuit from. Also has the much needed pictures.

The PWM Circuit I myself use for Fuel, LED dimming etc is this one

http://www.cpemma.co.uk/pwm_erg.html

Works good and can hold any amperage since that is a function of the FET/MOSFET current handling ability (seen them up to 100+ amps!)

as for his implementation.. let me draw a diagram (will take me about 30 mins).

 

[jdub]

I'm interested to know if this can be implemented with the TCCS (and how to) or does it require going stand alone (AEM)?

I don't think so...at least using the switch over point in the TCCS. If you could build a PWM circuit that accepts an analog input (say Ne or Boost psi) to control pump speed, it might be made to work.