Last weekend we raced our 2004 MCS at Carolina Motorsports Park. During the 5 hour race on Sunday afternoon, with about 45 minute left in the race, the car would die following hard righthand corners. The fuel gauge (navi style) was showing 4 bars or about half a tank. I pitted and 5 gallons of fuel was added. Things were fine until the final few minutes when the same issue surfaced again with fuel level down to around half tank. In the stint before mine, the car ran fine going 4 laps with the final bar on the gauge turned red. So quite strange to suddenly develop this issue. No codes or CEL set. Fuel filter had been replaced before this race weekend and we had no issues in the first 14 hours of track time.

Any suggestions on what might be the issue?

 

There is a suction "pump" that pulls fuel from one half of the gas tank into the other half where the fuel pump sits. If this isn't working correctly then you'll "run out" of fuel when you get down to about a half tank. The hard cornering is likely sloshing the fuel from one part of the tank into the other thereby starving the fuel pump.
The suction pump is just a venturi in the fuel lines - make sure everything is connected correctly and not clogged.

 

mrbean, Thanks for the reply. Is there a good diagram and explanation somewhere of the inner workings of the bit inside the fuel tank? I plan to pull the pump and filter units out of the tank to inspect everything. And given some posts I saw last night noting issues with seals in the Viaco brand fuel filters, which is the brand I';d used for the recent replacement, A new filter will go in.

 

I can't find a good diagram, but if memory serves me right, the suction pump is built into the bottom of the housing that holds the fuel filter. So it would make sense that an issue with the filter seals would cause issues with fuel flow through the venturi.

 

There is some sort of suction thing that is part of the furl filter housing. I opened up both sides this afternoon and found fuel level in filter side to be several inches higher than the pump side. Which would seem to point to a siphon issue. I've dropped in spare filter assembly & siphon that came our of a running parts car.

 

I have been thinking about a dual stock pump setup. Has anyone attempted this? I haven't found any threads on it last time I looked.