I have a stock fuel system other than an Aeromotive 340lph pump.The factory connector proved faulty, no big surprise, and I rewired front to back with 10 AWG. Getting 13+ volts to the pump and all seems good. What seems weird is I have 30psi of fuel pressure with 0 manifold vacuum and when I start the car, with about 17.5 inch of vacuum I have about 21 or 22 psi of fuel pressure. I thought I had higher fuel pressure before the stock wiring gave out, but I can't remember for sure. The other weird thing is after rewiring the pump, even though the pressure seems low, the car is running rich and I had to adjust the fuel map to compensate. Should I be checking fuel filter or for leaking injectors? Any help is appreciated.

Again, for reference, stock fuel lines and injectors, 340lph Aeromotive pump, and IGN1a coils. Stock port, stock turbos, just open intake and exhaust.

 

How are you measuring fuel pressure?

It's possible the pump is leaking back into the tank, like if the pump outlet O-ring isn't situated/installed properly or torn. Did you use the stock O-ring setup in the tank?

If you say you're running rich with it I'm really wondering if you are just not getting a good read on fuel pressure, like a bad gauge or something. I assume the gauge is hooked up to the feed line going to the primary rail?

Dale

 

I was using the stock o-ring and I noticed it leaking back into the tank a little bit. Since then I ordered submersible fuel line, cut the feed tube and installed hose onto that. I have been reading pressure using both an inline sensor hooked up to my ECU and a separate fuel pressure tester that I hooked up just before the primary fuel rail. I did not notice a substantial change in pressure after changing the method of connection.

 

If you had tuned the car in the past with bad fuel pump wiring then yeah it should think it'll run rich with the new pump and proper wiring. Is it running rich at idle or under boost?

The pressure thing is odd tho. With a similar setup I am ~32 psi base at idle, then the pressure matches boost in lock step. I also have the aeromotive 340.

Try another FPR?

Good move on the hose. The stock connection is janky for an aftermarket pump. Are you still using the white bulkhead connector in the pump hanger or did you bypass that?

 

FWIW I just installed a new Aeromotive Stealth 340, car would start, idle and drive around at slow speeds fine. When I would get on the throttle, car would starve for fuel. I pulled the pump and everything looked fine with the installation. I put a fuel pressure gauge on the fuel rails; I would get the required 60 psi at idle but pressure would drop to 30 psi when revved. I changed regulators to rule that out, same problem. Pump is NFG.

 

Did you get the fuel pump from a reliable vendor?

Also for your application I would have recommended the Walbro 255. Again, you have to get it from a reliable vendor, but they are drop-in and work great. Mine's been running for 10-12 years now with absolutely zero problems.

Dale

 

I am swapping out the FPR this next week and will see if that makes any difference. The fuel pump came from CJM, I believe them to be reputable. I will post back when I get the FPR changed and see if that makes any difference. I'll keep looking for any other ideas or suggestions.

 

Stock FPR?

Dale

 

I have a stock FPR at the moment. Trying an aftermarket unit this next week.

 

So, very delayed response. Been super busy. I replaced the fittings and put in an aftermarket FPR and adjusted to 43psi with no problems. Now I have other issues popping up. Not sure if the issue was the OEM FPR, but I do at least have the pressure where I expect it to be now.