Howard Coleman

iTrader: (6)

i was doing some road tuning yesterday and experienced something new (!) as to my fuel pressure. it took a brief dive and then recovered. not good. fortunately no harm to the motor.

here are the details:

time 47.976 seconds
Differential Fuel Pressure 41 psi
Fuel Pressure 67.4 psi
Boost 26.3
.96 Gallons per minute

time 48.411 seconds
Differential Fuel Pressure 7.5 psi (!)
Fuel Pressure 39.9 psi
Boost 32.3

time 48.729 seconds
Differential Fuel Pressure 38.6 psi
Fuel Pressure 71.2 psi
Boost 32.7
1.34 gallons per minute

in .435 of a second my fuel pressure dropped from 67.4 to 39.9 and then recovered to 71.2 in .318 of a second. my AFR briefly went to 15. fortunately my timing responded to zero and my motor is fine.

BUT, i don't want to do that again. it was totally out of the blue, up to now all has been well in the fuel department. i am running a 285/Hellcat pump at 17 V in boost.. other than switching to the 285 pump i have run this setup since 2013.

i am swapping in a new fuel pump relay and have checked all the wiring. the pump has a pressure relief valve but it triggers at 112 psi.

most logical to me is my pickup momentarily caught some air. i was in a straight line with 12 gallons in the tank but was heading pretty fast towards 600 hp (EFR9180). has anyone on the board had starvation with around a half a tank?

any other ideas?

Slides

No surge tank then? Quite possible. It's usually one of the first mods most Aussies do. A few guys just using double pump hangers in tank but they are usually dyno queens or street cruisers.

What were road conditions like? Any chance of a wiring fault? The AFR shifting with pressure would seem to rule out sensor. Is your wideband directly controlled by the ecu or digital format?

I have a surge setup from a local shop but if I was going again I think I would be using the B2A drop in surge tank.

I think I had a couple of moments of surge doing a track day with only basic mods around half a tank when I first got the car.

Howard Coleman

iTrader: (6)

"No surge tank then? Quite possible."

yes, it appears to be the problem. i have rechecked my wiring/relays etc, talked to TIAuto and Radium. also reviewed lots of helpful threads on the subject. i ran a Hyperion cover for my fuel pickup box and somehow it ended up in another box in my shop so i will, today, reinstall it in my tank. i would do the Radium deal if i were to be doing some future road racing as the Hyperion setup appears to be marginal near 1/2 tank in left hand turns. i just need straight line fuel for the Texas Mile. if i have any future issues i will do the Radium deal. i will also add a low Differential Fuel Pressure ignition response.

j9fd3s

iTrader: (3)

i've seen the baffles break in the gas tank, its an FD.. also the newer tanks get different baffles
if this applies info is here https://www.rx7club.com/3rd-generati...mbers-1131674/

if it doesn't apply, i've seen starvation at half tank usually you need a turn, but maybe 600hp would help