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Author Topic: Fuel pump voltages  (Read 2617 times)

Ryeoon

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Fuel pump voltages
« on: June 11, 2014, 06:48:19 PM »
Hey guys, looking for info on fuel pump voltages as I've heard wiring a Walbro or other pump on to your factory fuel pump wiring will not have the pump run at it's full potential.
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30ed32

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Fuel pump voltages
« Reply #1 on: June 11, 2014, 07:14:50 PM »
You don't need to get that same part number just a regular relay with a fuse inline.

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Ryeoon

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Fuel pump voltages
« Reply #2 on: June 11, 2014, 08:12:33 PM »
Say I'm going to hard wire my fuel pump to a kill switch though, what is the voltage of the stock pump compaer to what is need to run a walbro efficiently?
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30ed32

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Fuel pump voltages
« Reply #3 on: June 11, 2014, 09:32:52 PM »
I think stock is around 12v maybe just a little bit under, the walbro will still run fine at that.  It will just run better if its hard wired which is then around 14v.
« Last Edit: June 11, 2014, 09:35:04 PM by 30ed32 »
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Ryeoon

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Fuel pump voltages
« Reply #4 on: June 11, 2014, 09:50:37 PM »
Bingo. But will it mess with my tune? I don't think it should but can always be wrong.
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benji-nz

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Fuel pump voltages
« Reply #5 on: June 11, 2014, 10:09:22 PM »
The regulator should keep it in line? Then again you might see a small gain. Did you install a gauge on your Tomei Regulator?
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Ryeoon

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Fuel pump voltages
« Reply #6 on: June 12, 2014, 06:24:23 AM »
Yeap gauge still on reg
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downtrail

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Fuel pump voltages
« Reply #7 on: June 12, 2014, 08:06:19 AM »
Don't wire it to a switch use the computer to control the pump safer if you crash and tear a fuel line and the motor will stop and the fuel pump will stop with it. if it was on a switch it'll just keep pumping fuel out and fuel the fire say. You'll find that the configuration I sent to you for E&H when you were having fuel pump problems will prime the pump at 8v then after motor rpm is greater than 500rpm it'll switch to battery voltage. Use a meter and check it no point putting in another relay if its already running at battery voltage. if its lower then its probably volt drop and running a thicker cable for the pump feed to the fuel pump relay from fuse box and from relay to pump will fix that. you could also ground the pump locally to rid volt drop in the earth circuit. think it runs the entire length of the car and earths up front somewhere.
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xxfr

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Fuel pump voltages
« Reply #8 on: June 12, 2014, 08:57:44 AM »
The diagram that 30ed32 has posted is pretty good ryeoon. If you want to put the kill switch for security reasons, by all means install it inline on the "original grounding wire" on that diagram. This will mean you get full battery voltage and your pump on/off is controlled by your ecu and you still have a kill switch. If case of a crash, the car turns off, ecu turns off , the pump will turn off irrespective of whether the kill switch is on or off.

Your kill switch off will mean you have the ultimate control of your pump. Hidden in good location, its good secuirty to prevent thefts.  

Do check the wire sizes in the diagram and make sure they suit your new pump requirements.
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gtsr

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Fuel pump voltages
« Reply #9 on: June 12, 2014, 01:18:17 PM »
Stock is around 10-12V. 10 volts is at higher rpm.

Fuel pump lph is rated at 13.5 volts for most aftermarket fuel pumps that I know of.

If a tuner has tuned the engine, probably would have hardwired the fuel pump already.

Ryeoon

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Fuel pump voltages
« Reply #10 on: June 12, 2014, 02:38:38 PM »
I've emailed E&H. They never touched it even though I asked them to.
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xxfr

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Fuel pump voltages
« Reply #11 on: June 13, 2014, 12:35:49 AM »
Typical E&H.
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westybob

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Fuel pump voltages
« Reply #12 on: June 13, 2014, 04:49:03 AM »
Your fuel regulator means that if you hardwire the pump it shouldn't make any difference to fuel pressure.
The plusses are
1. Your fuel pump will last longer operating at optimum voltage
2. You will have extra capacity if you decide to go for more power.