I recently did my first track day since going turbo and first time on NT-01's (from Azinis). I exprienced fuel starvation around the same turn every time I ran with the tank lower than 1/2 tank. Fill it up and no issues. I never had this problem in the past, but never ran tires this sticky.

Is it normal to experience fuel starvation at these grip levels?

 

No. Miatas will run right down to E without issue (even on Hoosiers). Better check that your fuel pickup sock is in good condition.

 

I replaced the fuel pump/sock with the turbo install. I might have boogered something up. Worth checking I guess.

 

Definitely not normal, Miatas will run on fumes with Hoohoos and aero.

 

Did you use a stock fuel stock? Or a walbro sock?

 

either wrong sock, or incorrectly installed assembly/pump, or something else.

 

Or maybe it's just not actually true that all Miatas will run on fumes on the track. Mine won't, Ed's won't, several others won't. Mine has no broken baffles and a brand-new factory sock and still starves powering out of left handers when it gets down to 4-5 gallons left. A suggestion has been made that it might be the removal of the NB in-tank regulator that hurts it, due to the return pipe dumping the fuel halfway down in the tank. I stuck a camera in there and recorded it (not while moving) and it doesn't really appear to be that big of a deal. So I dunno. Rallas appears to have an NA, so presumably he hasn't removed an in-tank regulator.

One thought is that the "will run on fumes" allegation is (AFAICT) primarily based on endurance racing Miatas, particularly various cars owned/run by Emilio. Note that these are all naturally aspirated cars which suck down a whole lot less fuel per second than a turbo car does. I have read that the reason you want a factory fuel sock is that it lets fuel into the sock fairly easily, but prevents it from draining out quickly. In effect it's acting like a small surge tank. If so, then it's possible that this small reservoir of fuel is enough for a 150-180 rwhp to power out of a corner, but not enough for a 300+ rwhp car to do the same.

For my car I've basically just been avoiding running it low by filling up every couple sessions.

--Ian

 

If I don't start a track session with at least a quarter tank, I will experience a fuel cut kind of symptom during a long left-hander. Maybe it's an Emerald Mica '99 thing.

 

Happens on my 91 on the street, thought I might have mounted the pump and therefore the sock too far up. But, last time I checked it was firmly against the bottom of the stock NA lower rubber grommet and foot. I was planning on removing the rubber grommet next.

My tank does not have tall baffles, its a small tray with maybe half inch tall walls. It would not hold much fuel where it needs to be. Can't find a good picture online, don't think my tank is modded or busted. Can't see any broken spot welds...

I replaced the entire fuel system and lines, the filter, the sock twice...

Hope my new one doesn't have this problem.

Edit: Here's what the inside of my tank looks like.



Is the sock supposed to be under that hole???

 

I only had the issue on turn one at CMP which is a left hander, not real long left hander though. No issues on any of the other turns.

I replaced it with an aftermarket sock that that looked identical to the original one removed with the original OEM pump, nothing special.

 

Which turn at CMP? I have never had any fueling issues at CMP with my turbo 94. Had it down to less then a quarter of a tank many times.

 

Turn1

 

Does anyone have the part number for a factory fuel pump sock/strainer? I cant find any factory socks online.

 

 

I've run/raced (and regularly for weight savings) down to the E many times racing. Never had fuel issues, ever. Most races I start at 1/4 to 1/3 full.

Stock fuel pump, regulator everything. 1600 turbo with 260 hp atw and now with the 1800 at 320+ hp atw (though we did change the pump to the DW one at the engine upgrade).

edit to say: No jinxes.

 

Yeah, I've put 12 gallons in an NA Miata at the track. Bone stock, never opened gas tank.

 

A stock NA6 tank setup will fuel starve with ~10oz left in the tank

 

It looks like that is a NB part number. Does the NB sock fit NA pumps? I have a Bosh factory replacement pump in my 91.

 

 

Thanks! That's much cheaper too! Is that the factory part? Everyone seems to think that the factory sock/strainer retains fuel better than aftermarket socks/strainers.