Fuel pump issue in TPI to Carb swap
08-02-2017, 12:22 PM
#1
Fuel pump issue in TPI to Carb swap
Swapped in a carbureted 383 stroker SBC into my (originally TPI) 89 Firebird Formula. Fuel pump will prime when the key is in the "on" position, however when the engine turns over it will not deliver any fuel.
I know it's a fuel issue because if I manually feed fuel into the carb it will run. If I prime the fuel pump a bunch of times I can get the in-line fuel filter behind the carburetor to fill up, but as soon as I start it, it consumes the fuel and leaves the filter empty and stalls out.
SPECS: 383 stroker SBC, 13:1 compression (yes the fuel is high enough octane to run in this engine)
750cfm Edelbrock 1407 (brand new)
Holly 12-803 fuel pressure regulator, hooked up to the stock fuel pump with return line sending excess pressure back to fuel tank.
Hi-torque starter is enough to easily turn over engine.
ECU is still in car, and (should be) controls only the VATS, fuel pump, and gauges.
Brand new fuel filters (even the one under the car)
Things I've tried:
Grounded out the black wire going to the fuel pump after the fuel gauge pegged out (MAX) when I put fuel in the tank.
I have grounded out the stock oil pressure pigtail (out of the three terminals, I grounded the top one, which makes the oil pressure gauge peg DOWN, thus not telling the ECU to cut off the fuel)
Help me TGO, you're my only hope.
I know it's a fuel issue because if I manually feed fuel into the carb it will run. If I prime the fuel pump a bunch of times I can get the in-line fuel filter behind the carburetor to fill up, but as soon as I start it, it consumes the fuel and leaves the filter empty and stalls out.
SPECS: 383 stroker SBC, 13:1 compression (yes the fuel is high enough octane to run in this engine)
750cfm Edelbrock 1407 (brand new)
Holly 12-803 fuel pressure regulator, hooked up to the stock fuel pump with return line sending excess pressure back to fuel tank.
Hi-torque starter is enough to easily turn over engine.
ECU is still in car, and (should be) controls only the VATS, fuel pump, and gauges.
Brand new fuel filters (even the one under the car)
Things I've tried:
Grounded out the black wire going to the fuel pump after the fuel gauge pegged out (MAX) when I put fuel in the tank.
I have grounded out the stock oil pressure pigtail (out of the three terminals, I grounded the top one, which makes the oil pressure gauge peg DOWN, thus not telling the ECU to cut off the fuel)
Help me TGO, you're my only hope.
08-02-2017, 02:17 PM
#3
Re: Fuel pump issue in TPI to Carb swap
So jumping the stock oil pressure sender pigtail only turns the fuel pump on when I jump it. I need the fuel pump on when the car is running. Anybody have any ideas?
EDIT: I think it is worth mentioning - the stock oil pressure sender port has been plugged by my engine builder, so instead of struggling getting a socket down there, I plugged in a new oil pressure sending unit next to the distributor in the oil pressure sender port. The ECU reads oil pressure from the stock 3 prong pigtail, which is now unplugged. I have grounded out the top wire of the 3 prong plug in order to keep the stock oil pressure gauge from pegging out (which would in turn shut off the fuel pump).
EDIT: I think it is worth mentioning - the stock oil pressure sender port has been plugged by my engine builder, so instead of struggling getting a socket down there, I plugged in a new oil pressure sending unit next to the distributor in the oil pressure sender port. The ECU reads oil pressure from the stock 3 prong pigtail, which is now unplugged. I have grounded out the top wire of the 3 prong plug in order to keep the stock oil pressure gauge from pegging out (which would in turn shut off the fuel pump).
Last edited by Wickydooda; 08-02-2017 at 02:49 PM. Reason: Extra situation details
08-02-2017, 11:40 PM
#4
Re: Fuel pump issue in TPI to Carb swap
SOLVED: I made an adapter Tee to run both an aftermarket oil pressure sender (because the new oil pump will run at a higher pressure than the stock gauge will read) and the stock oil pressure sender (in order to keep the ECU from shutting off the fuel pump due to no reading of oil pressure), and they are both plugged into the oil pressure sender port next to the distributor. The other oil pressure sender port on the driverside of the engine block has a plug in it still from when my machinist put it there. Easier to make a $20 adapter to run both senders than it was to fit a wrench down there to remove the plug. Now that the ECU is reading the oil pressure it does not shut up the fuel pump in "run" mode. Car runs fine now.