Fuel starvation, who else?
 

I put this in the DDM thread, but in case you aren't following,

So, on the fuel starvation issue. I experienced the same thing today on my car at Road Atlanta during the BMW Oktoberfest lapping days, turns 1 and 7 (right handers). Oil temp was approaching 260 and I thought and was focusing on that. Took a couple cool down laps, then went at it again going into the back half of the track, but for me, coming out of turn 7, the car totally died.

It wouldn't restart and fuel gauge showed empty. Wound up getting towed in, then filled it up and it only took under 14 gallons to fill it completely.

Now that I know what it was, I think that if I had ever completely shut the car off and then restarted it would have worked, but I never did that since I thought it was out of gas (even though it was half full when I started, after 3 previous sessions), and the car thought it was out, so it shut down the gauge and fuel pump?

Regardless, its very embarrassing to get towed off the track, especially at a national BMW event for running out of gas. Other than that, the car is feeling pretty good.

Haven't been on the track yet, But i think it will happen to me and anyone who's going to track their car. It's been awhile since the problem have cored on the surface, and no solution yet!

I haven't been in a situation with fuel starvation. So this is new to me. So far what i know is there is two solution. Either replace the tank with a better designed one, Or a fuel surge tank (witch i think will be an ideal solution for most of us),

I've been doing my own research and I only came across this item from SPL website Sard fuel surge tanks

http://www.splparts.com/main4/parts/...lSurgeTank.jpg

Sard website

Scott at Fontana nissan said they are working on developing a surge tank kit also.

when my engine was cutting out at the track, i thought it was related to limp mode, but looks like it *might* be fuel starvation. when it happened to me i was at about 1/3 tank and it was most noticable going up the hill (top of 2nd gear, shifting into 3rd) just before the last two turns before the front straight at sow. the thing that makes me think it's fuel starvation is that if i am hard on the gas, it would cut out (engine almost shutting off, but not quite). it happens at around 5-6k rpm. but if i very slowly rolled on the throttle, it would rev all the way up to redline. and when it happened, my oil temps were only about 240-250.

i thought that hitting limp mode in the previous session somehow caused the ecu to not let the engine rev up again in subsequent sesssions, even though oil temps have gone down.

so at this point, im thinking it was probably fuel starvation, but am still not certain that it was not some form of limp mode....

does anyone know if it is required to reset the ecu after limp mode gets activated? or do you just have to let temps go back down and the car will behave normally again? answering this will allow us to rule out fuel starvation or limp mode.

I ran into the same scenario last weekend. I thought the car was in limp mode but when I hit the long straights, the engine was reaching max RPM's. Oil temps were reaching 270-280. I also thought it might have been the VDC kicking in on exit through the tighter corners. I didn't consider fuel starvation. I will pay closer attention next time out. I should have any oil cooler by then.

I've had both happen on several occassions... when it is limp mode you will know it for sure because the motor / throttle will abruptly cut-out at a very specific RPM, but under that RPM it will work just fine

Whereas fuel starvation you lose all throttle regardless of RPM. It can be for just a moment, or it can be so severe that it last a few seconds... if it last a few seconds, you have a very good chance that the motor will turn off all together, which has also happened to me on the track

Got a stumble on the track today at 3/4 full. Filling up every session now.

yup. and those 'stumbles' are no biggie if you're just out for a DE, but in time trial can cost you a second or two and in a race could cost you a position... it's pretty frustrating... we need a vendor to offer up some packages to fix

hmm.... i'm not sure now. from what you're describing, it now sounds more like limp mode, since it only does it above about 5k rpm. but the weird thing is that my temps are only around 220 (cooled back down from about 280+ in a previous session). and it only does it if i'm "pushing" the car hard. (will not cut out if i gently roll on the throttle - in which case i can rev it all the way up to redline).

fuel starvation

boosted, its still probably starvation, especially if you are getting it after right hand turns.

In my case, I think I have gone from having it happen around 1/2 tank to 3/4 now because I switched from used R888s to Goodrich R1s. The grip is awesome, and the new brembos really rock.

spl parts sells a surge tank kit, but I don't know if I have the patience to install something that complex, or if I want to pay someone else to do it for me.

Damn - starvation at 3/4 of a tank with tires is pretty out of control. I"m not there yet, but I'm still on stock tires.

Strangely, the surge tank may be one of the best weight single saving devices around. If they can allow you to run 10 fewer gallons of fuel, that's 62 lbs. I assume they weigh in under 5 lbs for the kit. Anyway, that's 30-55 lbs. less fuel weight you're carrying around just to avoid starvation.

Good point !

We ran into this problem as well. Anything less than a topped off tank would lead to starvation. We haven't made the jump to R-comp's but i'm sure it would be a nightmare.

+1 on the weight saving nothing having to run a full tank.

Were in the process of putting together a swirl pot and small pump for our car.

Here's a simular set-up I had in my GTR, something like this (smaller scale) would be perfect.
http://i10.photobucket.com/albums/a109/Paul2x/gtr-2.jpg

glad to hear AE will be stepping up to build/offer a swirl pot... I think there will be a healthy market for this product... there are at least 3 options I can think of

1 swirl pot
2 gut and replace the fuel system... fuel cell, lines, regulator, pump etc
3 custom in-tank 'can', as discussed on my build journal

#3 would involve building a 4-6" diameter cylinder with baffling that can be put in around the fuel pump and would act as a staging area for fuel and resist the flow away from the pump in right hand g's... just a theory at this point, but the guy posting the idea on my journal designed and built one that went into production on an unnamed GM car... I like it b/c it would cheap - avoiding the cost of the extra pump for a swirl pot

Yeah, I think the simple baffle around the pickup could work for most of us. Although if you're building an all out race car you might as just replace the tank and the rest of the fuel system.

I aggree 100%. Travis is on to something. Defently worth trying that opton first b/c swirl pots and pumps can add up quick.

The 944 turbos and 968's have a quasi baffle around the pickup but they will do the same thing you are experiencing with the Z.

For my 944 turbo GT3S car I put in a surge tank. Get a 3.5 to 4" ID aluminum pipe and cut to length for your installation. A 3.5" x 12" tank will store about 0.5 gallons. TIG a plate on the top and bottom and add the connector bungs. I did the following: a line from the fuel tank to the surge tank top, a line out of the surge tank bottom to the fuel rail, a line out of the fuel rail to the pressure regulator, a line from the pressure regulator back into the surge tank top and then a return line from the surge tank top back to the fuel tank. I used braided stainless lines and AN fittings. It really isn't too hard to do.

I'll see if I can get a couple of photos of a friends car who has the same setup and post them.

I would appreciate that. Filling up every session is kind of a PITA. My amex card doesn't like it when I use the same pump more than 3 times in a day.

I haven't been paying much attention to this until now. I am heading to the track this Friday and I too have noticed with normal street driving, something that I can only describe as "fuel starvation" where the car will studder a bit at lower rpm's after I have hit redline and really got on it. If I push it into higher rpm's again, it will go away and pick up again like I got kicked in the ***.

Is this an accurate portrayal of what you guys are experiencing with the fuel starvation mode? I haven't been paying attention to the fuel tank level during these little episodes as I thought it was a bad fuel filter or something.


Dumb question...

This "fuel starvation mode" is triggered by the computer right? Is it safe to assume that since I already have an ecu tune on the car, that this problem can be addressed with further tuning? (As opposed to putting all that extra and no doubt expensive gear in the car)

The fuel starvation is a mechanical issue, the fuel is pushed away from the pickup by cornering or acceleration forces. The starvation event can sometimes be delayed by a second or two, as you may have enough fuel in the lines to complete the corner but it dies at the end. It's not an ECU problem, although the ECU may prevent the engine from firing unless there is full fuel pressure, where as older models may have allowed the engine to fire.

Thanks for the clarification ChrisSlicks. Why oh why do they not put the fuel pickup at the REAR of the damn tank?? Ummm Hellloooo

Anybody heard anything else on this? I had a long day at the track today and started having fuel starvation problems around half a tank. Been filling up right before I get to the track, but after some extended track time today, tank started getting down to the problem level. Would love to see the trap around the fuel pump/pickup, seems like the easiest and most straight forward.

Might be a stupid question.....
The pump and sending unit seem to leave a significant opening in the tank. The secondary pumps are certainly a sexy option, but why not just fill the tank with fuel cell foam? Should stabilize the fuel and it is way cheaper. Not going to be a perfect fix, but will certainly help.

After looking at the tank, it looks like if one of the "wells" of the fuel tank goes dry, it could cause an issue. I would think that either foam in the wells, or foam in the "bridge" part of the tank to prevent rapid transfer from one side to the other should help the situation.

I just fill up after every session and no more problem.

Yeah, I had to go fillup to finish out the day. We had the track all to ourselves(me and 4 others) so they were not running the garage area. Had to leave the park drive 4 miles, fill up, and then return. But if this happens at 1/2 tank, I am just concerned when I go run something like the tail of the dragon, where it's damn inconvenent to fill up with quality fuel. Oh well I'll just keep watching to see if somebody comes up with something. Guess I'll cruise over to JB's build site to see if anythings new.

New year bump.

I too would love for a shop to take on this challenge.

This thread should be a sticky till the problem gets solved.

Or we (hopefully) wait for a fix from Nissan in newer Module Z's and just replace the parts needed.

Yesterday was my 2nd track day in the 370Z. 1st track day I did not experience any fuel starvation...probably because I kept the tank very full due to the rumors. Yesterday They did a time attack event at the end of the day and I had 3/4 of a tank left and thought, "4 laps is not worth going to the gas station and back, I should be good". I was wrong. Hard fuel cut coming out of right hand corners. I am going to have to keep the tank full at the track until a solution is found for this.

I'm still planning to try and work up an inexpensive in-tank solution next 2-3 weeks... hopefully someone else tries the external swirl pot solution and we can compare notes

import111...that sux
travisjb...keep us posted :tup:

Always remember to fill tanks only 90%

why 90% ?

perhaps you mean no less than 90% ?

Interesting topic, amazing how many glitches a sixth-generation Z can still experience. Looking forward to hearing about a fix to this.

My last time out at ACS I experienced a cut out just as I was leaving the staging area and not in a turn and with a 1/2 tank. The car just cut out. I'd let off and give it gas and then it would cut out again. I'm not sure which RPM. I went back to the pits and filled up and when I tried to start it it would not start as easily as it used too. At one point I wasn't sure if it would start at all. After awhile it started like normal and everything was ok. Funny thing is, I've run the car at Willow almost on empty and didn't have a problem.

Stan

where you going CW or CCW at Willow ? I'm guessing CCW... issues arise in hard right hand turns

I had no issues at the Big track at Willow CW or the streets CW. At ACS I was just starting to leave the starting area and didn't get 100ft when it cut out. I pulled to the left and let everyone pass by me and then backed up to get off the starting grid. I wasn't even on the track yet. It was flat and straight. Go figure.

Stan