LT1-7

We just installed the A1000 pump and everything was good until adjusting the fpr. When we first turned the car on, it showed only 35psi. So we turned it up to 40psi. Plugged the vacuum line back in and fuel pressure doesn't drop like it's suppose to. Oh well, we took it for a drive and fuel pressure does not go pass 40psi no matter what we do. So I test the voltage and found it to be only 6volts at idle. Then we hotwired the pump to 12v and got 60psi just like that. Adj the fpr and everything runs fine.

So what's the deal? Should I just run the pump at 12v? The pump's loud at 12v but so is the exhaust

Also, to get the stock fuel pump wires to run 12v all the time I just jump the fuel pump relay connectors right?

jimlab

You should be driving the pump directly from the battery with a relay triggered by the fuel pump lead of your ECU. The Aeromotive pump is going to draw a lot more current (or try) than the stock pump, and you absolutely should not be using the puny stock wiring to power it.

Aeromotive sells a fuel "computer" to control voltage to the pump, BTW. Unfortunately, it's not cheap.
http://www.jegs.com/cgi-bin/ncommerc...67&prmenbr=361

As far as loud, most big external pumps are. That's why I'm running twin in-tank Bosch pumps instead.

LT1-7

thanks jim. That's what I was going to do since the battery is already in the back. The thing I'm worried about is running the pump 12v all the time. It's not the loudness that scares me, it's the torturing tone it makes. Sounds like the pump's gonna puke a big hairball or something

InsaneGideon

Just to be sure:, you're not running the FP through the stock resistor, right? I suspect you ripped that out long ago.

RotorMotor

iTrader: (5)

thats the price to pay for running that unit though ... definatly upgrade your wiring though. i wonder if there is some way to insulate the pump so it isnt so loud... dyna mat is what first poped into my head... just a thought, but maybe some sort of sound insulation or enclosure if its external (but id be worried about trapping heat) may work?? just some thoughts.

im planning on running 2 cosmo pumps intank to aviod the loud sound, but i will most definatly upgrade the wiring.

PS hey jim, got any more info or pics of your 2 pump intank setup?

Flybye

If you didn't know allready, the ECU regulates the amount of power that goes to the fuel pump with the Fuel Pump Resistor . Lower than battery voltage is supplied during vacuum. The juice is turned up when you begin to boost. Even with the stock pump, I'd reach FP levels of 55-60psi when around 13.5psi of boost.

The fuel pump controller, just like the stock fuel pump resistor, is a great idea IMHO. After all, there is no need to be constantly running the pump at full blast is there.

I've always wondered if the resistor could deal with the load draw of a larger external fuel pump. Probably not since almost everything in an FD is underengineered You could always be a trooper and experiment for us

LT1-7

Flybye, looked like the the resistor doesn't work with higher output pumps. Not only did it not give me enough pressure but the whole pump just kept on jolting wanting to give me pressure but was unable to.

Another reason I think lower voltage off of boost isn't a good idea is because when I ran the pump at 6v it showed me pressures of 40psi. Right when I gave the pump 12v it jumped right up to 60psi. Imagine if you got that 6v to 12v transition while boosting. Your pressure not only will raise because of the fpr but also the pump from the voltage transition.

I guess I'm just going to run this 12v all the time to be safe.

LT1-7

Some people have ran this pump intank. That came into mind but I'm running a fuel cell and the pump won't fit inside I don't think. The pump isn't as loud as I thought anyways. The free flowing single turbo with a strait out exhaust covers most of the sound coming from the pump

Flybye

LT, when the stock setup basically supplies power to the pump, when you begin to boost the fuel pressure is only at about 50 or so. Then, of course, fuel pressure begins to rise as boost continues to rise.

It's probably not a good idea, but if you are curious to go with it, solder thicker wires to the resistor and wire it up to the pump. I haven't really looked at the wiring of the resistor, but if the resistor gets its power directly from a battery source, and the ECU simply regulates the resistor inside, then beefing up the wiring to and from the resistor could prove to be useful. If the resistor gets its power directly from the ECU, then thats a different story. You would still have to end up dealing with the **** wiring coming from the ECU and the fact that the power has to come directly from the ECU is another matter.

Then I'd probably adjust the FPR so that once the new pump gets battery voltage, you can start off like at 50psi of fuel and it will slowly work its way up with boost.

I've never actually tried any of these, but in theory, it makes a little bit of sense

RotorMotor

iTrader: (5)

hmmm i wasnt aware that the ECU was aware of the fuel pump... i just thought everything was self contained and any excess pressure was dealt with by the FPR? that seems to be the best setup to me.... if there are wires coming from the ECU to the fuel pump and you disconnect/ cut them, will the ECU complain or notice?? sorry, i havent studies the fuel system indepth yet hehe -heath

InsaneGideon

...so you DIDN'T remove the resistor then?

As for the resistor being "underengineered," it's actually engineered specifically for the current/load characteristics of the stock pump. A larger pump will generally pull more current through the resistor, so there will be more voltage loss at the pump. Or you could look at the resistor as being a current-limiter. Either way it'll power-starve a bigger pump. Anyone considering a pump replacement of any sort should consider the effects of this.

From what I remember the resistor gets its power directly from the battery (well, going through a small maze of fuses), and the ECU controls a second speed relay that bypasses the resistor.

I'd imagine the Aeromotive pump driver is actually a PWM driver like more modern cars have... or like the dash-light dimmer is. Since they're claiming cool operation it'd almost to be.

DamonB

This is correct. The ecu controls the fuel pump relay and that relay is really only the fuel pump resistor bypass. You can pull the fuel pump relay and the car will start and idle just fine but the fuel pump will never be able to go to high speed mode with the relay pulled.

Flybye

No because the ECU is connected directly to the relays and the resistor is connected to the pump.

Here's a little schematic to help you understand what is going on.
It first routes power through the circuit opening relay. When full power is needed, the middle relay is activated completing a full connecton. Actually, looking at this now, it doesn't look like it is a variable resistor/power regulator.

AND since the pump is directly connected to the resistor and relays, maybe someone could experiment beefing up the wiring from the resistor. I'm sure one of the elec engineers here could even open up the resistor and see what the limits of the internals are to determine if it could withstand a larger pump, but even then, it might not even matter!! The resistor is bypassed when you begin to boost which is when you need the max voltage going to the pump. You could always simply leave the regular wiring from the reistor in place and beef up the wiring from the pump relay once it is activated.

LOSTinWANKELS

i got the same one on my talon.....its a loud sob