I have a 1985 RX7 race car which competes in the SCCA Improved Touring Sedan class. It has a 13b motor in it. I just purchased it.

Towards the end of last fall, I had it out on the track for the first time on a track day. The track was Lime Rock.

The car ran fine all day, but at the end of the day, during the final few laps, the car began to stutter in just one corner.

I don't know if you know Lime Rock, but as I ran through the "esses", which is essentially a quick left hand turn, the car ran fine. But as I took the right hand turn to go down the back strait, the car would stutter and stumble until finally picking up and accelerating down the back strait as if nothing had happened. It started out as only a brief stumble but got progressively worse every lap.

It seemed like a fuel starvation problem to me. I noted that I started out with a full tank and it was at the 1/2 level when the problem started. Then again there's the situation of taking a left hand turn and then an immediate right, but that was not a problem earlier in the day. Perhaps a heat or fuel boiling problem?

Any ideas? Any idea where I should start?

I was thinking of installing a larger pump and a pressure regulator at the carb. Has anyone had any luck with this and what equipment did you use?

 

Fuel filter?

 

I would think its a sloshing problem because as you turn right all that gas jumps to the right side of the tank and the pickup is on the left side. A bigger pump or higher pressure won't help. Only two ways to fix it that I know of; a slosh can up front or a fuel cell to replace the tank.

I have no clue what they allow in the class, just my 2 cents.

 

Carter pump and holley regulator, do a search, its been done a million times over

 

I had the same problem and it was the fuel filter. For a $4 part it won’t hurt to try it.

 

Could be a hole in the pickup tube. Once the fuel level is low enough, when the fuel sloshes to one side you might end up sucking a little air into the line. Maybe install some baffles inside the tank, or check the tube itself for any corrosion. Maybe move to a fuel cell if that's allowed in your class.

Take a look at float levels too, just in case...