ive been having this on going issue of a random lean condition at higher rpm at high boost in 3rd and 4th. obviously not a good time to be going lean.

at first we thought it was spark blow out, but my tuner isnt able to make it happen for him at the track, so its almost impossible to track down.


i think maybe the fuel is creeping back away from the walbro in tank fuel pump. im working on an electric sensor to datalog fuel pressure but dont have that at the moment. mostly wondering if anyone else has had this problem?

we filled the tank up to half tank with c16 and made one more pass, and it didnt go lean. but one pass isnt enough to say for sure if the problem was solved with more fuel as it seems to happen randomly...


we double and tripped checked all wiring and everything is good (unless possibly the relay is twitching out while being powered).


heres a screen shot of a datalog from tonight where it happened.

 

How much fuel do you run in the tank? A few friends used to have issues past a certain power level, with the 255 in a stock tank. I always kept over 1/2 tank.

 

I agree we always try to keep ours full

 

fuel in the tank on that pass was about a 1/4 tank. then i added more c16 to just under half tank.looks like its time to sump this thing.

 

so i tune this car.

on the dyno, there are no issues.

at the track ive only made 3rd gear pulls and one all out pass, always with a decent amount of fuel in the car.

so thats why im leaning towards the fuel pump running dry. too bad the fuel pressure gauge is under the hood. hah.

interesting to see feedback from others!! thank you

 

our shop car will go lean with a 1/4 tank even on the dyno, it has a sumped tank. it wouldnt suprise me at all if that is the problem. I know gas isnt cheap but rebuilding the engine because of a stupid mistake isnt either.

 

thanks for the feedback man.

 

Time for one of those sensor I link'd to you for some logging I asked Darrin before, but what pin is the wideband wired too?

 

ya man now u know why i was asking. lol

i also want to run one on my coolant system to watch for pressure spikes aka detonation, i think it would work very well.



we run his on D14 and we run it on the stock LC1 0-5v scale

 

I've logged my fuel pressure and it tanks and causes an instant lean condition under hard acceleration when I drop below a 1/4 tank. This is with a single intank walbro 400.

 

fuel filters dirty?

 

thanks for the confirming that sohc mshue.that is exactly what is happening.i have a single intank walbro too.ill just keep 5 gal of c16 in the tank at all times.

 

BALLLLLLINNNNNNNNNNNNNNNNN

 

even with well over 1/2 tank of c16 it went lean around 8500 -9100 rpm. turned it down to 19 psi and it diddt lean out.gonna get rid of the y8 style rail mounted FPR for a external one. also add a bosch 044 inline pump.