S2Bray

I experienced intermittent, but repeated hesitation from the engine, following gear changes (up). My gut feel is some G-related pump struggle, but I’d appreciate any trackday go-ers thoughts on this.

The Facts:
In all cases the hesitation occurred after (but not during) a corner, and only after the next gear change. Eg coming out of a third gear bend, throttle wide open into the straight, shift into 4th, throttle wide open = immediate hesitation/stutter for a fraction of a second, then normal progress.

Observations:
I was sharing the drive with a friend – this never occurred during his laps. This is what makes me think some G related struggle, as it being my familiar car, I was inevitably carrying brisker pace.

It only happened in the afternoon, after a good number of sessions in the morning. Was I getting quicker? Was something degrading?

The problem hasn’t occurred since leaving the track, (covering well over 100miles) which is why I’m leaning away from something spark related.


In the back of my head I’ve got baffled sumps (which I don’t have) and fuel swirl pots (which I also don’t have) but I don’t know what the symptoms are present if either one of the pumps is starved, to know if my symptoms align, and are calling for one of the above

Wisdom/experience welcome..

MB

Left handers?

Fuel pickup is on the left side and low fuel can starve the pump. There is a lag there as you have the length of the fuel lines as a damper.

Hopefully not oil pressure affecting VTEC.

S2Bray

Yes, left handers. I'm racking my brain, but I can't recal it happening after a right hander. Is there a solution to this other than keeping the fuel level above 1/3?

S2Bray

Also, would you expect fuel starvation only to present itself following a shift and not say mid bend in gear?

EDIT - just seen you comments about fuel lines

MB

Sounds like fuel surge / starvation.

If it's not a track / race car just fill it with extra fuel. You're not looking at lap times so 10-15 litres extra fuel won't hurt.

I have a twin pump setup in mine with a surge tank, but it's noisy and extreme for a road car to go down that route.

S2Bray

As you correctly identified - that would be overkill for what is an occasional track steed.

Thanks for putting my mind at rest

markforrester99

Rule of thumb for me was to not let the car run below half a tank during trackdays. I also made sure the oil was at the top of the dipstick to fend off any starvation.

Are you sure you have the OEM pump as replacement pumps if fitted poorly can change the height of the pick up and that might cause you issues.

S2Bray

I can't be sure, no. To my knowledge its never been replaced.