I've felt this surge in two different scenerios.
First: straight line acceleration after lifting off accelerator to shift then quickly getting back on throttle. (stock pump, hasn't happened in straight line again since change to walbro 190 hp)
Second: At track this weekend while quickly lifting off throttle for turn and then quickly getting back on throttle.

Common factor with both scenarios is that when I'm under hard acceleration I lift of the gas for a fraction of a second and then get back on hard. The car bogs and has no power. Engine still running, but pressing accelerator has no affect. I have to feather gently on and off with the gas to regain power.


I first thought that the turbo was somehow vapor locking and needed a few seconds for the pressure to drop on one side of the system or the other.

At the track it happened in two different spots. Both happen to be in hard negative camber left hand turns. This has led me to believe that it might be a fuel situation. Is it possible to slosh the fuel in the tank over enough for the pump to suck air??? The first time at the track it happened, the fuel tank was full. The first time at the track I actually had to coast out of the line and pump the gas peddle a few times to get anything to happen. Subsequent events I was able to feather pedal as stated above.

Fuel pump is a walbro 190 hp, installed a month ago. Fuel filter is new.

Has anyone experienced this, or have any ideas about the cause?

 

bad electrical connection, fuel starvation, dead pump, or retardation. Actually, probably a combo of those, most likely severe retardation is part of the problem.

I've run on "E" at the track and never had a starvation issue.

 

here's my timing map