I’m having problems with I think fuel starve situation and I cant figure out why.

Only happens in a long sustained sweeping left turns on race rubber. Car will just shut off for a second at the end of a long left hand sweeper. Stops doing it If I have a half a tank or more. I use to run basically on empty and never had this problem before.

I have taken the fuel pump out looked at it and the sock and everything seems fine. I replaced the fuel regulator as well.

I’m stumped, any Ideas?

Bob

 

Maybe you're getting faster, pulling more G's, and using more fuel in the corners?

 

There may be something to that, I've had a Co-driver for the last several events and he has not experianced it. I have consistantly been a second or two faster though autocrossing and a Time Attack on a small track.

But I know there are tones of fast people on sticky tires driving miatas and almost never do you hear of fuel starve issues. Something must be not quite right with mine I figure.

Bob

 

fuel cell?

 

Wirelessly posted

Still on a factory fuel sock oriented in the factory position? I had serious starve issues in my car with a walbro sock. Spun the pump to the correct orientation and installed the OE sock and all problems are gone. Also make sure you are using a 1.8 hangar with your 1.8 tank or 1.6 hangar with 1.6 tank.

Spec miatas only starve when there is less than a quart of obtainable fuel left in the tank. When we start to see starve in high-g cars (hoosiers and aero) it will be at <1/4 tank, not 1/2 tank.

 

I have a factory fuel sock but the pump is far from stock I rigged up a Denso pump made for an Mitsubishi 3000GT, same size as a 3rd gen RX7 pump and much bigger diameter than a Miata pump so things have been modified. It flows as much as a 255 walbro at but is completely silent so I don’t have to listen to the walbro whine. My initial attempt I used a sock from an RX7 and that didn't work at all, Id get fuel starve every left turn I made on street tires with a half tank. I then rigged up the miata sock in the correct orientation and had zero issues for about a year.

Upon close inspection though now I think the pump might have rotated a bit and a portion of my braketry pried against the sock. It might have lost its seal to the pump. I fixed it and will see if it works the next time out.

Bob

 

How does it feel when you experience this kind of starvation? I have this issue since the last event on one particular left. If feels like overboost protection kicking in, so not subtle.

 

When I have fuel starvation on left turns it is very abrupt and as you describe similar to overboost protection.

If anyone cares, this is a stock MSM fuel system, 1/4-1/3 of a tank, RS3s, on fairly tight left hand sweepers (Turns 3 & 9 here: Mission Raceway Park - Wikipedia, the free encyclopedia)

 

I'm lisfting this.
Did rotating the pump work?
I had this problem with the oem pump n/a, on street rubber. then it was with 1/4 tank.
Now i get it with my 190 walbro on track, on r-compounds whenever exeeding 1.1g. Now with more than 1/2 tank! And just having 15-20 liters of fun before having to refuel is awful, as is the extra weight when doing timed laps.

My oem sock was really dirty and old, so I'm thinking about getting a replacement one instead of the small walbro sock, but if anything else can be done to remedy the situation at the same time I'd appreciate if you posted it.

 

And with a brand new oem sock the problem is gone.
(as per forum advice).