Having a problem with maintaining consistent fuel pressure. The problem is, when My coolant fans turn on, The Aeromotive 1000 External Pump slows down from lack of available amperage. I can see the Batt volts go from 14.1V at Idle to 12.9V when the fans come on, with some other accessories on also, like headlights and radio. This in turn leans out my A/F, because Fuel Pressure drops. A/F with no other draw besides Fuel pump and engine running is 12.5:1, when fans come on, it goes to 14.2:1. I have been trying to tune this car for approx a week now, and have not been able to get it right because of this. I just figured out this is the problem why my A/F is always changing so much. I tuned it at oper temp, I guess the fans were on. When I started it today, and read the A/F before the fans came on it was at 12.5:1, at idle, way rich. As soon as the fans kicked on, Batt volts went from 13.9-14.1 to 12.9-13.1, and A/F went to 14.2:1. I bought the car from Another member on this board, and I seen that aunderdrive pulley was installed. Also, Overdrive pulley was installed on the Alt. My question is, Should I install stock size pulleys to fix the low Batt voltage, or install a higher amp alt? Will the Batt voltage still drop alot when the fans come on with the stock pulleys? I am running the stock TPI fans, and they both come on at the same time via a Accell ECU at 185deg. I havent checked the amount of fuel pressure that drops when the fans come on yet, but you can hear a difference in fuel pump noise when it happens.

 

Are you sure your fuel pressure regulator is working well and isn't maxed out (ie set against the stop at a high setting)?

You're always going to have some pressure fluxuations from the pump from different battery loads, different temperatures, etc and the pressure regulator should be able to smooth that out and keep your pressure pretty constant.

You can keep the voltage at your pump higher by running a thicker gauge wire directly from the alternator to the pump and also making sure the pump ground is good and uses a thick gauge wire, but your voltage drop now isn't too bad and the regulator should be able to take care of it.

Paul T.

 

fuel pressure is set at 43 psi when fans are not on and no other loads. I have 10 and 12 gauge wire for the power and ground to the pump. Does anyone sell a type of resistor you can install in line to your 12v supply wire to the pump to only allow 12v to the pump at all times? If so, I can set it at my desiered pressure, and not have to worry about the change in pressure. The 1 volt drop I get from the fans kicking on is excessive, I dont know if its the ALT not being enough amp, or the pulley not spinning fast enough because the crank id underdrive. The crank pulley is 5 1/2", and the Alt is 3".

 

Check the fuel pressure first. Probably not an issue.

Most likely need to correct the injector compensation for battery voltage. The lower the voltage the longer it takes for an injector to open. Hence the leaner AFR.

RBob.

 

Cannot adj pulse width for voltage difference with Accel Gen 6. But, I put the stock Crank and Alt pulleys back on the car, and its great. Voltage is 14.3-14.5 with no fans on, when fans come on, voltage drops to 13.3v, then jumps right back up to 14.3V. It jumps back to 14.3V so fast the A/F doesnt change, so all is good now. Thanks

 

I believe Aeromotive recommends this with the A1000 pump. Got one?

http://www.aeromotiveinc.com/product...tsub=0&prod=31

 

Yeah, its a A1000. But its plumbed all wrong by Brutalfourm, going to plum it right in the spring.