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Intermitant Fuel Starvation

Fuel System

Model: 911 C2 Cab, Year:1999, Mileage:147500, Type of use:Both Street & Track
I am the second owner of a 1999 C2 Cab 3.4L, currently with 147,500 miles. Engine improvements include: FVD's ECU, BMC air filter, IPD intake plenum, Shnell headers and Tubi mufflers. The car runs as good as it can with 20mpg/city, +30mpg/hwy with an average of +25mpg. Oil consumption is one (1) quart/8,000 miles. I've not done a compression test or a leak-down test. Fuel filter was replaced about 10,000 miles ago.Here's my question regarding fuel cut-off:I participate in Gold Coast Region's AutoX series each year here in South Florida and noticed a repeating problem at our last event (eight runs for the day, four (4) runs back to back in the morning and four runs in the afternoon.) In late October the air temperature was 65 in the AM to 78 in the afternoon. The car's fuel system would cut out momentarily (for about 0.50 of a second each time) half way through a 60 second run. Sometimes the apparent fuel stumble would happen two or three times in one run as the day went on. As you can imagine my times would be better if this was not happening. Typically for the first of the eight runs, Ill try to keep the car in first gear to 7,000rpm in the first part of the course, but later runs I'll shift to second gear sooner and keep it there for the full run. If I find the car is going to be slow coming out of a tight turn, I'll downshift to first and accelerate to 6,500rpm then shift to second for the next part of the course. Pedro Bonilla, of Pedros Garage, a good friend, has suggested the old fuel pump and relay are heating up causing this stumbling along with the G-forces in the corners where this problem would occur, might be the culprits.I would like to know your thoughts regarding this problem.

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