My fc3s is huntimng at idle, due to running too lean. after checking loads of stuff I find the fuel pump is only seeing 6 volts at idle, if the car is revved voltage goes up to 10 volts. Can the wiring really get that bad or is it more likely to be the fuel pump resistor relay thats not supplying enough voltage to the pump?
I know on the fd the voltage at idle is 9v and you get full voltage under load so I presume the fc3s would be the same?

 

TIIs will switch the voltage between idle/cruise and load, but N/As wont. Sounds like you need to rewire the pump, the voltage is low. This is a common problem with our cars.

 

Cheers, looks like I have some wiring to do then.

 

Enjoy it, I know I did!

 

I'm confused. You have a WHAT YEAR CAR??? Profile says 98??????

 

Put your bifocals on old man!

 

Check out your fuel pump resistor system.
I'm assuming this is an FC turbo.

I did some preliminary poking around there, and I found some interesting stuff.
My fuel pump resistors was measuring around 1.0-ohm.
It's supposed to be slightly lower than that according to the FSM and the resistance spec stamped on the resistor itself!

The wiring was NASTY!
I tried to rewire and solder, but solder won't even stick to the oxidized wiring!
My voltmeter was showing around 8.0VDC, and the damn thing would not switch consistently going into boost.
Eventually, the relay stuck so it was always on "high", but the voltage was still only about 10.0VDC.

I've now rewired it temporarily (Haltech E8 ready to install soon), and it gets full voltage ~13.5VDC.
Amazingly the car runs very good even with the higher fuel pump voltage.

Good luck!


-Ted

 

Thanks for that Ted, when I rewired my fd I went from afr in the 10's to the 8's. Amazing what 13.5 volts will do for a fuel pump.

 

That was a long time ago. I own a 93 single turbo and
also a 1990 single turbo

 

TIIs run fine at full voltage to the pump at idle, the downside is crappy in town gas mileage, you also may not pass emissions with the pump doing full duty at all times.