howardteets

Just to clear things up. I know mlx8 said this happened to him during a right turn. Is this the same from everyone. Looking at the tank setup, if this is a fuel delivery problem the stall is more likely to happen during a left turn.

One other question: Are the stalls happening on long extended turns under wide open throttle?

Speed Racer

In my case the engine stalled immediately after going flat out through the esses at Watkins Glen. Which happen to be an uphill right, left, right. It is a very fast section of the track and I would imagine that the turns generate enough force to hold the fuel to one side of the tank or the other. Oh and the tank was at 1/3 full when this happened.

howardteets

mlx8 thanks for the info. I can't make too much of the system from the file. It's good to have but the service manual pages aren't too detailed for this type of trouble shooting.

I would hope that no one has had to change the fuel pump yet but... What are the chances anyone has pictures of the actual fuel pump module?

drumsmith

Actually, I had this problem at Memphis Motorsports on the front straight. Granted it was after a 180 degree right-hander, but it seemed as if the 3rd injector wouldn't work due to the engine's sensed low fuel pressure. When I got up to 6500 rpm or so (roughly) the engine would go dead until rev's dropped back down. Also note that I was halfway down the straight and therefore had been traveling in a straight line for some 1/4 mile by that time. Fuel guage read approx. 1/4 tank, but when I came in, the needle would rapidly drop down. One time the service engine light came on, too. Fillup fixed it tho, and the light went off.

My theory was that we're running a lot less fuel than the gauge shows on the track, and under those conditions, the car is trying to protect itself. Make sense?

mlx8

Well, I would think if one counted the number of gallons need to to top off the tank, you'd have a "no gauge involved", absolute true measure of whether the tank was a 1/4tr or less.

FWIW, based on my experiences, it's not the gauge that's at fault. Not sure what you mean by "... the car is trying to protect itself...."

As an aside, but WRT "protection" I think something like this would be of even greater concern to some one running & tracking a boosted engine. Partly dependant on how much boost one runs, it doesn't take many moments of running lean under boost to harm stuff.

howardteets

Try judging how much fuel was used by noting how much was needed to fill up after your run. Saddle tanks are very susceptable to erratic or erroneous gage readings. With the saddle tank (some not all) there can be dead spots in the tank where the float can not reach to read the fuel level. The vehicle will have to rely on counting injector pulses based on rpm and throttle position to estimate fuel usage until the fuel is at a readable level. This is not usually an issue during street driving.

Performing manuevers which will cause slosh (ie. racing) causes the level sensing system to lose track of where the fuel is causing erratic or incorrect gage readings. I don't know if this is an issue with the 8 or not but is possible with a poorly designed tank.

ULLLOSE

iTrader: (1)

At the recent SCCA solo2 natl tour in Atwater we got into fuel starve. We were at 1/4 tank. It happened at a very fast spot on course, 2nd gear over 8500 rpm wide open, upshift beep was on. It was a combo of left, right, left lane change. It was just a hickup on corner exit. The car made it fine the rest of the run. Added one gallon and did the next run no problem. This surface is VERY grippy concrete, I think on asphault we could run lower.

mlx8

This is a cut & paste of a post in one of the original fuel starvation threads just as a FYI. Occasionally I run a "fuel starve" search since this became a bit of a hot button issue for me with the car to see if it's ever been addressed by Mazda, or if I'm just having a princess and the pea issue:

I had to pull the fuel tank (actually bought a new one) and have a second, small transfer pump installed in the tank to pump fuel from the side of the saddle without pump into the actual fuel pumps catch can cell in the other saddle. I'm now able to run the car almost to "empty" on the fuel gauge at the track without fuel starving. Before the modifications, with track tires on I would get starvation with the gauge just below the 1/2 tank mark (this particular track had a very long, NASCAR type, banked high speed left hand sweeping turn.)

Interesting to me, that I haven't seen a lot of other posts complaining about the problem, or notwithstanding this threads early speculation that Mazda ".... knew or knows about this, and is working on a fix...." I've never seen a recall or other notice addressing what, for me at least, became a significant track safty issue. Nothing like trying to hold and balance the car on the edge of a high speed sliding corner while either chasing (not so bad) or being chased (much more worrisome) and only to have the vehilce unexpectedly stutter and loose power. Not happy with Mazda about this oversight, and so far as I know failure to address the problem. Otherwise its a great car, but the fuel starvation engine in a "zoom-zoom" advertised car IMO is a major faux pas.

dmp

EXCELLENT! How much $ would that procedure cost? Pretty simple, I'd guess, for somebody who knows what they are doing.

mlx8

I see that since this thread was started, the fuel starvation issue, and related questions about a solution, along with endless new speculation as to causes continues to roll along. No, it's not a matter of a weak pump, or clogged fuel filter, or low voltage, or contaminated pick up.

It's the result of a poorly designed or implemented fuel pick-up in the gas tank itself. The $1,000+ cost to me was to have purchase a new tank, have it sent directly to SpeedSource where, as I understand from the shop who did the R&R of the tank on the car, the solution involved the addition of a second, small auxilary electric pump to move gas from one side of the saddle to the other. Cost of the actual parts used to fix the problem, minimal. Cost of knowledge to know what to do, and how to do it ~ well SpeedSources bill for the surgery to the new tank was @ $800+ as I recall. And that would be exclusive of the cost of the fuel cell itself, and shipping charges to/from Florida.

FWIW, I was told by SpeedSource that their solution would result in the loss of fuel gauge function. By the time we turned to them for a solution, running on a modified suspension (front & rear sway bars, tower braces and coil overs) with DOT R compound tires, we were starting to see power loss in corners from side G loads, approaching the half (1/2) tank level. One of the nice things about starting with a brand new tank was, once we had the tank back, the shop was able to reposition and fix the modifications inside the tank to restore full fuel gauge functionality.

Now we can run the car down to just short of the reserve light coming on without hitting fuel starvation. As fast the Rx8 can chew through gas on the track, this is a very welcome modification. The shop still has the original tank that came out of the Rx8. I haven't asked, but they might be willing to look at doing a modified tank on some kind of exchange basis. No idea of the cost.

HTH

TeamRX8

iTrader: (25)

yeah, I've been telling them the same thing and they won't believe me either ....

https://www.rx8club.com/series-i-aftermarket-performance-modifications-23/speedsource-parts-rx-8-a-83108/

mlx8

I think the fuel tank modification will have been a very WELCOME thing for the up coming One Lap of America we're planning to do in the car this year.

Worrying about having enough gas in the tank to do the timed laps without fuel starving is one less thing to foul up on, in an event in which managing required things to do, and the time that can be alloted to them is crucial. Arriving at an event with less than full tank of gas, and being able to run without having to search for a fill up may turn out to be a very handy thing.

Cheers