I currently have a stock tank with bladder, stock 3/8" lines, 110 gph GM perf mech pump, 6an line going from pump to 750cfm mighty demon blower carb. I currently dont have a fuel pressure regulator. Also I dont have any return to tank.

I'm having a fuel pressure dropping problem. gauge shows ~8psi of pressure at idle and cruising. When I rev it, pressure drops slightly and when i hit WOT pressure drops to around 4psi sometimes.

I have a 350 with 144 supercharger it made 365rwhp and 410rwtq w/6-7psi of boost. My AFR was 12.8-12.9 but I noticed fuel pressure drop on dyno after 4000rpm. I want to get fuel pressure to hold and bring AFR down to 11.8, I think I'll be safer and might make more power. Also I want to add a nitrous plate system to this combo this summer. i want to do a 100-125hp shot and i need to set up my fuel system to safely fed the motor n/a and with a little nitrous.

my plan:
I want to keep the stock tank and remove the bladder form it, run 8an for the whole fed system. I was thinking of swapping to a Victor jr. 130gph mech pump and running an (3-15psi)aeromotive regulator. I was thinking of adding bulkhead 8an fitting at lowest point of tank and plugging stock sending unit fed tube. I dont want to add a sump, I'm on budget.

will this new set up provide enough fuel to fed my motor and be enough for small nitrous?

Would electric pump be a better option for my power level?

Do I need to run a reg with bypass and a return line back to tank? most aftermarket pump dont have a return line.

 

If I were on a budget,...I'd just take the fuel pressure guage off and let the rest of the system alone. My 406 runs a 130 gph mechanical pump, no regulator and a Holley 750 and will turn 7000 rpms never starving for fuel. I did have issues with the Edelbrock 1904 (Q-Jet clone) under heavy throttle where it would bog as it ran out of fuel in second gear at 7000 rpms. But that carb only had a single fuel bowl.

On a side note. My fuel pressure guage goes to zero when the engine is hot,.....but the engine still runs fine. Me thinks the guage is lying to me.

 

1/2" pick up....


http://www.robbmcperformance.com/pro...vettesend.html

If I was going to spray it and keep the blower, I would probably go to a dedicated pump/line for the nitrous kit. Better volume and better control of the lower fuel pressure required for the spray (4psi FLOWING)...

If you're dead set on keeping this all on a single fuel line and mechanical pump, I would get the 1/2" pick up I posted above, have them add the -10 male. Then I would run -10 all the way to the pump, then -8 from the pump to the carb and -8 to the fuel solenoid either from the regulator if you run one OR a T at the fuel line. At a minimum I would use the Carter 172 gpm race pump(no regulator required) or the Holley 170 gpm. Try not to run any 90* elbows if possible, if you do have to, get the smooth bend type from Earls or Russel. This should give you plenty of fuel supply for 650 crank HP or so...

You don't want any fuel pressure drop at the traps when spraying....not to mention your fuel pressure will plummet when the solenoid opens anyway.....Thats why its better to run a dedicated system and set the regulator with the fuel FLOWING through the plate(into a bucket)...... If fuel pressure drops too low when running NA, you simply nose over and lose power........If fuel pressure drops too low when adding boost or juice, you melt pistons/heads.

You COULD use the 1/2" pick up and use the 1/2" feed line to fuel the carb with a -8 line. Then use the 3/8" return port as a feed line to the nitrous system and run it through the stock 3/8" fuel line on the frame to feed the nitrous....You would still need another pump/regulator for the nitrous but this would be pretty cheap.

 

ALSO..... FWIW....

I run the Carter 172 race pump with the stock 3/8" fuel lines, stock pick up and even a nasty 90* pipe fitting elbow(extremely tight) at the pump and I do get pressure drop, even on just a dyno pull it will drop from 8psi down to about 4 psi...and thats only a few secs..... Yet at the track, my car maintains a 11.8 AFR through the 1/4. The leanest I have ever seen it was 12.8 afr on 40* night with a bunch of jet in the carb..... trapped 128 mph like that...i'm sure the fuel pressure was 0psi at the stripe....(don't have a gauge in the car though).... My car still gained 25 mph on the back half so it was not indicating a lean out even though the fuel pressure was low.....

BUT I am not recommending you try this, especially on the spray....

 

Thanks Alan, def some helpful info. I just ordered a AEM wideband o2 controller and gauge so I can get the tune perfect. Should be here friday and then Ill have my buddy weld in the bung for the sensor and I'll get it wired up for next week. There is a car show 4/9/11 at UCONN that I want to attend so im going to wait and redo fuel set up after that show.