Hi everyone.

I have an au xr8 220 manual with a custom tune and exhaust. All of a sudden it developed a fault. On occassion (although quite regregular) under full acceleration, at around 3500 to 4000 the car has a power cut. It looses all or most power for a split secondnthen seems to kick back in more ornless.

I ran the fault codes and it had a cam semsor fault. I replaced the whole cam sync and although the fault is gone the problem is not. The car now has no fault codes so the car does Not recognise the issue. I also reloaded the tune and changed the pkugs. No change.

Any educated ideas as i am stuck!

to me its displaying symptoms of a possible crank sensor problem, but with no code showing maybe its a momentary fuel starvation issue, ?

I was going to change the crank sensor just in case. Someone else suggested fuel and that I should try filling the tank and seeing if that makes a difference. I changed the fuel filter and apparently the pump was done 2 years ago but cant be sure.

This fuel surge is definitely the problem, the car does not do it with a full tank. What are the solutions other than a surge tank??

replace the fuel pump with a walbro gss341 255lt pump

And that will correct the issue?Are they a bolt in or require mods? ANy idea of the best place to get one at a good price?

Thanks!

I got mine off ebay was around $110..
but the cradle does need modifying to fit a walbro.
or you can try replacing it with a new std pump and see if that fixes it, maybe your pump is just tired?.

If it truely is a fuel pump issue, why would you recomend a 255lph fuel pump? It's way too big. I would be really worried about the capacity of the factory FP regulator to bypass this volume of fuel especially in non-loaded conditions, leading to over-fueling issues. The factory fuel lines won't cope with this flow either, the return line is a smaller diameter than the supply line, so it will flow less fuel than the feed line for the same line pressure. And it will also dramatically increase heat soak into the fuel tank with a much higher volume of fuel being recirculated. Hot petrol isn't good

I have found a 155lph pump to be ample for 450FWHP. For comparison the stock fuel pump is about 100-110lph, and a 255lph pump comfortably supports 750FWHP. You could always calculate your fuel requirement and pick a pump with a suitable delivery map. But hugely bigger isn't better, it's worse.

If you think it's a fuel supply issue, and it isn't the filter, it might be worthwhile checking the pump screen first

I run a walbro 255 on my xr8 with no problems, it supplies more than enough fuel and wont effect anything, its a high flow pump not high pressure, the reason I say 255 is because there everywhere, there cheap and the std pump on mine struggled to keep up with the std 220kw engine..and the walbro 255 is rated to 500hp.

The map for that pump shows 265lph @ 40psi @ 13.5V. That calculates out at supporting 840FWHP NA on pump petrol.

I would not run a pump that size on a sub 450HP NA engine.