Pete Whitstone
True Classic
Hey all,
I just installed an Aeromotive 13301 adjustable fuel pressure regulator to bring down a slightly rich A/F mix the non-adjustable stocker had me at.
After a bit of fine tuning and some trial runs, I think I have it dialed in. Idle is slightly rich at low-13's, but cruise is right on at around 14.7, and WOT is low-13's or high-12's.
The only complaint is that on shutdown, pressure drops immediately to 0. So I guess the question is, does the stocker have some kind of check valve to prevent this that the Aeromotive unit does not?
I am guessing not - the Aeromotive design centers around a cone that ends in a ball shape. The ball shape is pressed into a seat by a spring on the big end of the cone. The ball and seat control the return to the tank (and thus the pressure). This is somewhat like a needle/seat arrangement on a carb. I'm guessing that for some reason, the ball is not completely seating, which lets the pressure drop to 0 after the pump shuts down. It seems to me that if the spring is providing, say, 28 lbs of pressure, and the pump 50, then after shutdown the fuel pressure will equalize at the springs static pressure. But the leak in the seat allows all pressure to be lost.
Or has this got something to do with the fuel pump - maybe it's losing pressure from the other side of the circuit. I find this a lot less likely, because with the stock regulator, pressure did not drop instantly after shutdown - it took a good 30 minutes or more for the system to bleed down.
What component of the FI system is responsible for holding pressure until the next start?
Somebody educate me here!
Thanks,
Pete
I just installed an Aeromotive 13301 adjustable fuel pressure regulator to bring down a slightly rich A/F mix the non-adjustable stocker had me at.
After a bit of fine tuning and some trial runs, I think I have it dialed in. Idle is slightly rich at low-13's, but cruise is right on at around 14.7, and WOT is low-13's or high-12's.
The only complaint is that on shutdown, pressure drops immediately to 0. So I guess the question is, does the stocker have some kind of check valve to prevent this that the Aeromotive unit does not?
I am guessing not - the Aeromotive design centers around a cone that ends in a ball shape. The ball shape is pressed into a seat by a spring on the big end of the cone. The ball and seat control the return to the tank (and thus the pressure). This is somewhat like a needle/seat arrangement on a carb. I'm guessing that for some reason, the ball is not completely seating, which lets the pressure drop to 0 after the pump shuts down. It seems to me that if the spring is providing, say, 28 lbs of pressure, and the pump 50, then after shutdown the fuel pressure will equalize at the springs static pressure. But the leak in the seat allows all pressure to be lost.
Or has this got something to do with the fuel pump - maybe it's losing pressure from the other side of the circuit. I find this a lot less likely, because with the stock regulator, pressure did not drop instantly after shutdown - it took a good 30 minutes or more for the system to bleed down.
What component of the FI system is responsible for holding pressure until the next start?
Somebody educate me here!
Thanks,
Pete
