Hi guys
I have extensively modified EFll Fairmont. 4.0 au block EF tickford head holset hx35 45 mm waste gate 3" exhaust 42lb injectors walbro 255 pump with xr6 regulator TI performance chip tuning plus shift kit
If I was to say mum was driving it's fine doesn't skip a beat. Lol.
But when dad takes her out and give it the loud pedal it suddenly dies till I back throttle off
afr gauge suddenly goes to 22.1 I've gone through checked the sort of things that I'd think and been on here reading few forums and changed what you would expect new coil pack. New leads. New plugs. New fuel filter Metered TPS sensor appears fine no check engine lights come up which I thought would have if was sensor fault ie. TPS. MAP I have replacement fuel reg but haven't changed as yet cause most people say the rich in not lean I seem to be chasing my tail Thinking pump but that's not that old but doesn't mean it can't fail Any ideas would be greatly appreciated
I'm old school 302 Windsor 64 Fairlane 4 Spd manual

Hi yes is a 300kpa reg And yeah fuel leaning out to maximum of gauge reading. on average driving sits on 14. Foot down 9 Unless it dies Lol that be why I never seen check engine light I'm just going on what I read on here the cars been built and going for few years I didn't build it myself but has been on dyno 305 kW And drove mint up until 2 months ago

The Walbro 255 fuel pump is too small. Step up to an aeromotive 340 or buy the Kemso 340 which appears to be the same thing.

Alternatively, fit a surge tank. use the Walbro to feed the surge tank and plumb something even bigger to feed the fuel rail.

Hi thanks for that I've been doing bit of reading and walbros seem to have more bad than good comments surge tank will be next move wouldn't need to be too big couple liters fed by tank and then return goes to surge ? Or just back to tank do I stick with existing regulator