Fuel pump amperage draw?

[Jim Craig]

Before you call any pump manufacturer, make sure you have all the engine and vehicle information -- size, horsepower, fuel being used, system pressure (very important), fuel cell or modified factory tank, exisitng fuel line configuration, bypass regulator (type & location).

The manufacturer should be able to provide either actual flow curves for the suitable fuel pump or the numbers for said pump. Biggest mistake in fuel system design is too much pump................it'll kill the engine's performance.

good luck

[buzzinhalfdozen]

Jim, I'd have to disagree about the biggest mistake being putting too much pump to the system. In this instance at least it's better to go bigger, bigger lines, bigger pumps, bigger regulators from my experience have no detrimental effects on engine performance. Of course the entire system has to be compatable, example don't put 5/8 line with marginal pump ect. Most companies have complete systems that are designed to work as a unit. Joe

[Jim Craig]

Originally Posted by buzzinhalfdozen

Jim, I'd have to disagree about the biggest mistake being putting too much pump to the system. In this instance at least it's better to go bigger, bigger lines, bigger pumps, bigger regulators from my experience have no detrimental effects on engine performance. Of course the entire system has to be compatable, example don't put 5/8 line with marginal pump ect. Most companies have complete systems that are designed to work as a unit. Joe

Joe -- I guess we'll have to agree to disagree; it is best to design the system to match the engine's performance -- not design on a hypothetical performance. You'd be surprised how the properly sized fuel system will actually pick up a car's performance, especially in the first half of the track.

[KRatcliff]

Jim Craig helped us with the size of the Weldon fuel pump and overall design of our system on our Super Stocker. The pump is far smaller than you would imagine and the car runs fairly well.

[art leong]

I'll probably wait till the PRI show and try to talk with the manufacturers.
I'm sure there is something to be gained by going smaller. With the present set up the voltage drops over 1 volt when I turn the pump on with the motor off. Can't tell what happens with the motor on because the motor shuts down immediatly.

[Axis Racing]

Art,

I may be going out on a limb here, but I think you may be looking in the wrong area. Kind of like using a butterfly band-aid instead of having a cut sewn up...

You touched on what I believe is the answer. Your ECU may be able to run anywhere from 8 to 20 volts, but the tune definitely changes. Rather than have to run the alternator, you could tune the engine at each voltage via the battery adder function. The correct way to do it is to tune the engine while it's powered by a variable voltage inverter. Tune the car at a given voltage, like 13v, then adjust the inverter's output voltage to match another cell on your battery adder table in the ECU. Adjust the adder function on both the ignition and fuel (most likely it's a multiplier on the fuel) untill the engine is making the same power at the new voltage and then move on to a different voltage. Tuning the battery adder stuff is quick and painless, all you have to do is pick a single RPM point and adjust the battery adder function to get the engine running correctly...

Once you've done this, you will be able to run sans alternator with a decent battery and not loose ET. More than likely, you're loosing between 8 and 12 amps to the fuel pump, and a bit more than that to the water pump. Start the runs with the battery at roughly 12.5v or so, and end it in the 11's. No big deal if the battery voltage correction factors are set correctly!

[buzzinhalfdozen]

Sounds like good advice, was unsure of Art's systems capabilities. My system also has a voltage compensation table however I've yet to use it, never saw a noticeable change in voltage on my runs. Joe

[Adger Smith]

Art,
What you might need is a step up in your electrical system.
There are a few systems available. I would give Pat Collins a call @ http://www.techwestracing.com/
704-995-4286
I got a well known Comp team hooked up with him and he helped their program. I can tell you first hand that his Max Power system made more power on a dyno I am associated with than just a good 12 volt battery with a charger attached. That was with a MSD 7 system and the appropriate coil. Listen to him when he talks about coils.

Also, I agree with Jim about the correct sizing of the fuel system. The bigger is better way is similar to what I call the "Shotgun Way" Throw enough lead at anything and you will eventually hit it. You need big enough, but too big has some problems like air in the system and heat soak. Plus a few other issues.

[Ed Wright]

The voltage compensation table is to correct injector pulse width, but that has much more effect at lower RPM, not so much at higher RPM. Adjust that table at one RPM and you won't see the same A/F change at all RPM. More low, less up high. The correct way to address it is upgrading the electrical system to stabalize the voltage. EFI cars, IMHO, should have 2 16 volt batteries or an alternator if 12 volts. Low voltage will certainly lean an EFI car because the injectors open slower. I had two 12 volt batteries with an alternator in mine, everything was fine until it suddenly began to kick alternator belts off. I could kiss about .05 worth of ET goodbye when it did that.

[Mike Pearson]

Why not run a separate battery just for the engine controls?