This is pretty much a cross post from the G20 forums, but I am hoping to find some answers

have a 91 G20 highport with a header,crank pulley and intake on it, no EGR or emissions equip, that I run at a circle track.

Early in races the car pulls great, runs strong and is damn near perfect....toward the end of feature races (20 laps) the car starts to lose power, the temp gauge doesn't show it running more than 3/4's hot and there are no other symptoms other than an obvious lack of power....after coming off the track it idles fine and again exhibits no other symptoms.

Any one give me a general direction of where I can start looking to solve this issue?

things we have changes/checked

knock sensor, changed...helped but still feels like timing is being pulled

injectors/FPR.. changed the entire rail (had gas in oil problem has been solved)

vacuum lines changed no leaks found

I run a stock radiator with water/water wetter/ stock cap and t-stat

I have an external fuel pump that isn't plumbed in the best way, maybe starving it under sustained loads?

http://img.photobucket.com/albums/v463/Georgethefierce/downsized_0509001304.jpg

i run 19*s of timing on 93 octane.

races are 20 laps (5 miles) car starts to lose power after 10 green flag laps

right now we're grasping at straws....is this the famous water pump issue? people run these motors for a lot longer under this load with no issues.

Is your pickup in the middle of the tank or the side? Is it possible your fuel level is getting low after those laps?

pick up comes down the side and ends in the middle....cell has a sponge and I keep a min. of 3 gallons in it.

Could be fuel starvation, or inadequate fuel cell venting.

pulled the plugs...they are 2 weeks old and carbon fouled, the car uses 0 oil, fuel is not the issue....leaning back towards heat.

fuel pump getting hot since its not in the tank? gas isnt there to keep it cool