[SSandman]

When I built my car, I wired up a spare under hood fuse box mounted mirror image to the factory one on the driver's side and fed by a 2 gauge cable from the alternator. Came very much in handy adding the accessories I needed while keeping it all clean and factory looking. Allows me to have fuses, relays all in one place and all fed from the same source.

Currently (no pun intended) it feeds my twin fuel pumps, my supercharger heat exchanger pump and I also wired up another relay/fuse activated with key on and then ran 10 gauge wire from that into my cabin to power an auxiliary key on fuse box for lower draw in-cabin accessories like my aftermarket gauges and heated seats.

Everything has been fine so far, when I kicked the boost up from 13 to 16 I began to stretch the limits of the heat exchanger system and I know I could benefit from a higher flowing pump less affected by the large head pressures created by a trunk tank setup in a 2000000 foot long car.

The pump most CTSV/ZL1 guys are having the best luck with are Pierburg CWA 400's. I'd like to swap to one, but the pump COULD see as much as a 36amp draw (supposedly it is usually 15-20a on most setups, but will depend on how much resistance the HX circuit has). The pump will be PWM because there is no need for it to be running full tilt at anything other than WOT, but for road race events I'd like to throw a manual switch in to kick the pump on full speed all the time to keep the blower cool.

Anyway, looking for a way to safely wire this beast of a pump in using the factory fuse box, which may be a challenge being the metri-pack 280 terminals that feet the relay posts I believe would be stretched past their limits given the charts I have seen.

Any ideas on what I can do? Gerry had mentioned at one point in an older thread about running parallel relays. I'm thinking that might be the ticket.
I draw a diagram below to show what I was thinking.


Anyone see any issues with this, or have a better idea? I think I probably COULD run the pump on one relay being most times I don't think these pumps draw more than 20amps at max flow in most systems and probably won't be doing it for long periods of time, but i'd rather be on the safe side.

 

[Z09B4U]

Redacted as I thought SSandman was referring to a fuel pump. Misread his post.

 

[Fix Until Broke]

Any reason not to use the maxi fuses in the fuse box? They're good for the current.

Looks like the PWM controller "bundle" has a fuse holder included (see page 27) - https://www.tecomotive.com/download/manual_tinyCWA_V3.5.pdf

Per the above (Page 3), it looks like the actual switching is done inside the motor itself, so just applying battery power directly to the motor via the big wire won't make the motor run. It's looking for the PWM signal (not power) from the little red box.

For an override, you can switch in a resistor in with the temp sensor to make it think it's really hot so it goes to 100%

 

[Z09B4U]

If you look at page 22 or later no relay is required on the pump circuit. Switched ignition power is applied to the controller.

CWA400 (pump) approx. 0.2mA in standby mode This is a very low parasitic drain. If correct I would not put a relay in the pump power circuit.

If the standby was 20mA my opinion is still to avoid the "twin relays" and use a 40A Hella or Bosch relay. As the pump power wire length is not too long you could use a Maxi fuse from the fuse box.

For an override, you can switch in a resistor in with the temp sensor to make it think it's really hot so it goes to 100%

See page 12 for the correct resistance.

 

[SSandman]

Plan was to use the maxi-fuses in the box. I could use one or two fuses to power two relays since the maxi fuse terminals are not the weak link. My issue was with the 280 series terminals on the micro relays since they would be stretched beyond their amp ratings with a 36amp draw IIRC. the maxi fuses use the larger 800 series terminals which would be fine with a 10 gauge wire.

But Doh, didn't even realize the controller may not require a relay. I was looking at a different (cheaper) PWM controller that was similar but I really like the one posted above.

That makes things a lot easier since I can bypass the entire relay circuitry in the under hood box which was really what I was worried about in regards to a single circuit handling the amperage.
Still not REALLY sure how much amperage the power strips of the fuse box themselves running from the bus to the maxi fuses can handle but I would imagine it's more than what I'm putting through it.

how to control the pump is where the issue comes in with that controller as temp controlled probably isn't going to work for my application. It's not like a typical coolant system where temps creep up. they'll heat up in a matter of seconds during a pull and the starting temps are very varied depending on ambient temps. What I really wanted to do was a manual way of switching so I can limit the pump to flow about where my current davies craig pump flows under most conditions, since that was working fairly well, then be able to set the pump for max flow only when needed at the track.

Any ideas on bypassing the temp sender all together and rigging up maybe some kind of two stage resister that I can switch back and forth from low to max flow?

I think most guys are running PWM pumps using controllers that run on RPM signal. It would probably work, but it's not ideal IMO as when I think the car is going to need the extra flow, I'd rather it be flowing at max all the time and not just at higher RPM's. When i'm on the street, I don't need it flowing max flow at higher rpm's. Makes it different than the fuel pumps most people are running PWM

 

[Z09B4U]

I really do not want to read this manual. But the controller claims it can be programmed for a minimum flow IE idle.

the issue comes in with that controller as temp controlled probably isn't going to work for my application. It's not like a typical coolant system where temps creep up.

Under temperature sensor control the manual says:
To calculate the optimal pump speed the controller is measuring not only
the current coolant temperature but also looks at how fast the temperature
is rising.
If the temperature rises too fast to counteract with the normal control
algorithm the controller will boost the pumps speed to its maximum in
order to get it under control.

As Fix Until Broke suggested you can "switch in" a low value resistor on the temperature sender circuit that should fool the controller into maximum speed. And you can program the maximum flow rate.

On page 15 there is information about using this controller to run the radiator fan. If you add a "solid state relay" (fan controller) this controller will co-ordinate the fan speed with the temperature. Or with a normal relay it will run the fan in on/off mode.

If you want 100% manual control get a PWM controller that can be modified with two fixed resistors or buy two PWM controllers and switch between them.

This controller is very programmable but it does not look like I would want to change things often

 

[nsaness]

Plan was to use the maxi-fuses in the box. I could use one or two fuses to power two relays since the maxi fuse terminals are not the weak link. My issue was with the 280 series terminals on the micro relays since they would be stretched beyond their amp ratings with a 36amp draw IIRC. the maxi fuses use the larger 800 series terminals which would be fine with a 10 gauge wire.

But Doh, didn't even realize the controller may not require a relay. I was looking at a different (cheaper) PWM controller that was similar but I really like the one posted above.

That makes things a lot easier since I can bypass the entire relay circuitry in the under hood box which was really what I was worried about in regards to a single circuit handling the amperage.
Still not REALLY sure how much amperage the power strips of the fuse box themselves running from the bus to the maxi fuses can handle but I would imagine it's more than what I'm putting through it.

how to control the pump is where the issue comes in with that controller as temp controlled probably isn't going to work for my application. It's not like a typical coolant system where temps creep up. they'll heat up in a matter of seconds during a pull and the starting temps are very varied depending on ambient temps. What I really wanted to do was a manual way of switching so I can limit the pump to flow about where my current davies craig pump flows under most conditions, since that was working fairly well, then be able to set the pump for max flow only when needed at the track.

Any ideas on bypassing the temp sender all together and rigging up maybe some kind of two stage resister that I can switch back and forth from low to max flow?

I think most guys are running PWM pumps using controllers that run on RPM signal. It would probably work, but it's not ideal IMO as when I think the car is going to need the extra flow, I'd rather it be flowing at max all the time and not just at higher RPM's. When i'm on the street, I don't need it flowing max flow at higher rpm's. Makes it different than the fuel pumps most people are running PWM

Hi SSandman,
Can you tell me what you ended up doing with your fuel pump situation? I do understand you are using the Phantom foam baffle in your tank, but are you running a second fuel pump? Is the second pump internal to the tank, or external. Is the second pump on a Hobbs switch, or by rpm? Thankfully, you wrote about your options and thoughts in different threads, but I am not clear on how you ended up. I’m moving to twin Walbro 450’s, which need about 30 amps each, and when search for others like me, this was one of the closest threads I found.

In addition to your wiring solution, what are you doing for your alternator? I think my V only has a 150 amp alternator…, but I could be wrong. Are you running a stock CTS-V alternator, or did you upgrade?
Thank you,
Mike

 

[nsaness]

I ended up activating the second fuel pump with a Hobbs switch with a [email protected] of boost. I also needed a new 200 amp alternator to feed the pumps. I think I’m good to go. Hoping for a tire shredding spring this year

 

[SSandman]

I ended up activating the second fuel pump with a Hobbs switch with a [email protected] of boost. I also needed a new 200 amp alternator to feed the pumps. I think I’m good to go. Hoping for a tire shredding spring this year

Sorry! I never checked back on this thread, impala has been in hibernation and never got around to the HX pump upgrade. I'm running twin aeromotive 340's in the bucket of the Phantom setup . the hat comes with wiring provisions for the twin pumps, and I wired them into my duplicate factory fuse box. I'm using a racetronix 7.5psi hobbs switch for the 2nd pump, it has worked flawlessly. I'm only running a 150amp alternator and haven't had any issues. I actually bought a 200 amp anticipating I would between the stereo system, twin pumps, HX pump etc... but never seen any voltage drop in any of my data logs...of course I'm usually not cranking the stereo during a pass. so far so good with 700whp, 16psi and ID1050X injectors on E85. Keeping the 200amp on the side just in case, still going to add heated seats to the car so who knows if that slight draw will be the tipping point LOL . I somehow doubt it, many late model guys with a lot more onboard electronics are running twin pump setups and 150a alternators without issue it seems.

Only thing I have thought a lot about is some type of failsafe for the hobbs switch since if the switch fails, you'll have just enough fuel from one pump to keep the engine going into lean destruction mode. Obviously it would be hard to cover all possible failures of the secondary pump system, but I figured the most likely failure would probably be the switch itself. Thought about wiring two in parallel, but if you don't bench test them often then eventually one might fail, you won't know it, and the second one could fail afterwards leaving you in the same predicament. Thought about wiring up an LED indicator to let me know the second pump is kicking on when I go WOT but I guess at that point I could just rely on my wideband instead of dividing my attention.

It's the one real flaw I see with twin fuel pump systems. Your whole engine is relying on one little piece of electronics. Not something I'd source from a no name amazon brand or something lol

 

[nsaness]

Sorry! I never checked back on this thread, impala has been in hibernation and never got around to the HX pump upgrade. I'm running twin aeromotive 340's in the bucket of the Phantom setup . the hat comes with wiring provisions for the twin pumps, and I wired them into my duplicate factory fuse box. I'm using a racetronix 7.5psi hobbs switch for the 2nd pump, it has worked flawlessly. I'm only running a 150amp alternator and haven't had any issues. I actually bought a 200 amp anticipating I would between the stereo system, twin pumps, HX pump etc... but never seen any voltage drop in any of my data logs...of course I'm usually not cranking the stereo during a pass. so far so good with 700whp, 16psi and ID1050X injectors on E85. Keeping the 200amp on the side just in case, still going to add heated seats to the car so who knows if that slight draw will be the tipping point LOL . I somehow doubt it, many late model guys with a lot more onboard electronics are running twin pump setups and 150a alternators without issue it seems.

Only thing I have thought a lot about is some type of failsafe for the hobbs switch since if the switch fails, you'll have just enough fuel from one pump to keep the engine going into lean destruction mode. Obviously it would be hard to cover all possible failures of the secondary pump system, but I figured the most likely failure would probably be the switch itself. Thought about wiring two in parallel, but if you don't bench test them often then eventually one might fail, you won't know it, and the second one could fail afterwards leaving you in the same predicament. Thought about wiring up an LED indicator to let me know the second pump is kicking on when I go WOT but I guess at that point I could just rely on my wideband instead of dividing my attention.

It's the one real flaw I see with twin fuel pump systems. Your whole engine is relying on one little piece of electronics. Not something I'd source from a no name amazon brand or something lol

I agree about counting on the Hobbs switch and timer.
We see the current fuel pump is nearing its max capability, and I’m just looking to make a little more boost. So the plan developed into a better tank and pick up/sump combination, dual fuel lines wyed and check valved in at the fuel rails, and dual Walbro 450’s (second pump staged at 4 lbs of boost).
As you can attest, twin 340’s can easily get you over 700 horsepower; but we are hoping one of the twin 450’s might still feed enough fuel (and still not run as hot as a bigger single pump) to avoid serious damage in the event of a Hobbs switch failure.
That hope could be ridiculous and stupid, but I understand that bad things can happen when you play this game. I’m prepared to replace the engine if I need to; but I am “hopefully“ building some amount of safety factor in with the steps I took.


My current single Walbro 450 “claims” this (below) and hopefully I never have to test those claims….
Dual channel turbine design for maximum efficiency under high pressure and high temperature applications
Made in USA by TI Automotive (formerly known as Walbro)

• Designed for engines with more than 750 HP
• Award-winning OE technology
• High-pressure, high-flow performance
• OEM technology designed and developed for E85
• Able to operate up to 87 psi total fuel pressure

 

[nsaness]

Oh; and I have run an auxiliary fuel pump outside the tank in the past, but it is so effin noisy; that I will never do that again. Back in 1995 the Vortech T-rex booster pump was so obnoxious that I vowed to keep all future fuel pumps in-tank.

 

[95wagon]

Gauge with low pressure warning that is programmable?
Set a couple pounds below your safe pressure ?


2-1/16" Fuel Pressure Gauge 0-100psi (w/ warning)

They can be ordered with an output to run one of their blinding shift lamps.
I have this set up on my oil pressure with the shift lamp right behind the oil light lens in the dash.

 

[nsaness]

Awesome idea. Simple for you; but I never would have thought of it. Thank you!