Dyno readout

[Dev]

Strange things have been happening in my SS ute (2003). The other day I was idling at the traffic lights and my L/100km readout jumps from 15L/100km to 23L/100km and then up to 26L/100km. After a slow acceleration from the lights (2000 rpm gear change) the readings then went up to 33L/100k! I can't seem to get the readout to drop below 19L/100k even when I'm driving like a granny. I took the car in for a dyno today and as you can see the readings fluctuated quite a bit. There is around a 20hp difference between the highest and lowest readout. On the first run (blue line) the fuel ratio was leaner than the fourth run but only registered a figure of 243rwhp. The fourth run gave me a figure of 265rwhp with a much richer readout. The green line suddenly drops off at 5000rpm as well. The time taken for all runs was about 10 mins with the car idling at all times between runs. I've been told my fuel pressure is fluctuating and the regulator might need to be fixed. Any ideas? Need some ammunition when I take it into Holden next week to get looked at (under warranty I hope).
Cheers,
Dan

.....can't seem to get image to appear on screen. Saved it as a .gif and .jpg. Any ideas??

[gtst4]

Well, presumably the L/100km meter is reading fuel flow. I'd have to agree with the diagnosis that the fuel pressure regulator is crapping itself, letting too much fuel return to the fuel tank at odd times. That would also tend to explain the lean running (low fuel pressure at the rail).

Get the dyno guy to hook up a fuel pressure gauge and take it for a run on the dyno.