Evo 8 issue

I'm asking here as you guy's are knowlegable on various motors,

Friend has an Evo 8 and has just had the engine forged it's now running just short of 500bhp, she had to have the Lambda sensor replaced two weeks ago as it suddenly stopped reading but then all was good with the new one and has been reading mid teens, we drove to JDM Combe on Sat (130 miles away) and drove fine but on the way back she noticed a "whirring" noise that rose with engine speed, we pulled into the services and whilst revving around 2k I could hear a rattle/rumble from low down in the block, the car then started missing, we looked at the oil and it was filthy (probably 1k miles since rebuild and was run in as per instruction) the oil also stunk of petrol.....she limped home and the car was cutting out at lights etc, when she parked up I looked at the plugs and they showed it was running lean, the AFR had been reading up to 20, the catch can we discovered was half full of petrol with a hint of oil.

It looks to me like the engine oil has been mega contaminated with petrol that has probably washed everything clean of lubricant but at the same time run very very lean, how can this happen when the only way the fuel can enter the motor is via the injectors and surely this would result in it running rich??????

The builder has looked at it and says that a seal under the fuel pump (in tank) had split and was to blame and that she needs to be in the AA so she can be recovered?????? not the sort of thing you want to hear after a 16k build......I can't get my head around how this "seal" could be at fault also, what are the odds of engine damage.....oh the builder also said that it was water in the catch can and not fuel........I know it was fuel because I tested it.

I'm no expert but something doesn't sit right with the "diagnosis"

Any advice is appreciated,

Thanks.

something like the fuel pressure regulator diaphragm split - this would allow fuel to be pumped into the intake via the vacuum line and from there fuel would go places you dont want it within the air system on boost and vacuum -injectors are not the only way in for fuel

Thanks mate