This past off season I built a 99. On low fuel loads the car would cutout on left hand corners. The problem getting worse as the fuel load dropped. At the first race I replaced the fuel pump with an aftermarket pump bought from the local parts store. It didn't solve the problem. The fitment into the fuel pump tree was also quite bad. I found a vacuum leak on the car and thought I had fixed the problem, but I found myself at another race with it doing it again. This time I changed the entire fuel pump bracket and pump with a used one that I found at the track. That did not fix the problem either.
After talking with people and researching it a bit more, the fuel pump bracket was still coming up as the most likely cause. Because I had replaced the entire thing with a used one, I was hopeful but reserved in thinking that a new one would fix the problem. What were the odds that two were bad in the same way? Turns out the odds were very good. I replaced it with a new one and also found a loose ground. I disconnected the ground completely and tested the car in the garage to see if it would start without the ground. It did. I didn't want to change multiple things in the garage as I like to know what was causing the problem. So I replaced the fuel tree and prepped to replace a number of other items at the track if that turned out not to be the issue. Went friday to a test day and the car ran perfectly. So instead of having to work on the car at the track, I was able to turn it into a good practice day with the new driver in the car. She whipped out 50-60 laps never putting a wheel wrong.
I really want to thank Jim Drago, Dave Wheeler, and Mark Nichols for their help in discussing this with me. The joint knowledge base these 3 people have is vast, and their kindness in helping guys like me is equally large. Thank you again.
On a side subject: I now have a bit of experience with a 97 NA 1.8, and 99 NB. I drive the 97 and I rent out the 99. There will be weekends where I have a choice of driving either car. Maybe its because I haven't quite dialed in the 99 yet, but there is no doubt that I would choose the 97 as the car I would want to drive in a race. The car is more nimble, lighter, and a higher rev limit than the 99. It is also easier to work on with less complications as the 99, but still has the 1.8 motor and OBDII. Maybe I will change my mind after more experience. But if there were no other considerations ( and there are ), Id choose to build another 97 instead of a 99. Out west there are a few of us that are beginning to think that the NA 1.8 in the hands of a young driver is a better choice.