Can an FPR be installed right after the fuel pump on a fuel cell?

[Juker008]

I was thinking, can a FPR be installed right off an external fuel pump that comes off of a fuel cell in the trunk? I do know that an FPR should be installed as close to the terminal point as possible. Reason that I believe is that the further away the terminal point is from the FPR the more the pressure drop. It makes sense, and the explanation isn't necessary.

Then this idea came to mind. Couldn't the FPR be placed right after the fuel pump, measure the pressure at the terminal point, and adjust the FPR accordingly to achieve the desired fuel pressure?


Thanks,



Juker008

[Goofynick6]

Has to be AFTER the fuel rail...so it can build the pressure between it and the fuel pump.

[325icintn]

Has to be AFTER the fuel rail...so it can build the pressure between it and the fuel pump.


If you wanted the regualtor near the tank for some reason
Couldn't you install it on the return line just upstream of the tank?
It means you're pressurising the entire return line, which is not critical either way.
Doing so might produce a little more fuel pressure fluctuation due to the length of pressurised line, though. Maybe even a lot of fluctuation, hmm...

EDIT - Nevermind. I didn't read closely. I thought he just wanted the regulator near the tank/pump. The most reponsive setup would be to have the external fuel pump/regulator just before/after the fuel rail. Oh the joys of gravity fed motorcycles with great big carbs.

[techno550]

it would be really slow to respond being that far back. you want it relatively close to the injectors.

[got psi]

Couldn't you install it on the return line just upstream of the tank?
It means you're pressurising the entire return line, which is not critical either way.
Doing so might produce a little more fuel pressure fluctuation due to the length of pressurised line, though. Maybe even a lot of fluctuation, hmm... Remember you have to run a vacume line back to the FPR and the length will have a lag effect on the fuel pressure. Just do the FPR up front and keep all the lines short. The return line is like dumping fuel to the atmosphere so there isn't any restriction(or not much). ///JT.///

[Juker008]

Now that you put it into perspective I see my flaw. Granted I can compinsate for the loss in pressure due to the distance from the terminal point and the FPR, but I can't compinsate for the pressure loss when the terminal point begins asking for fuel...or can I?

If I did do what I am planning, wouldn't the FPR simply adjust for the pressure drop?





Juker008

[Juker008]

BTW guys the whole reason why I would like to do it this way is to minimize the ammount of return line that I would need.



Juker008

[Juker008]

Oh the joys of gravity fed motorcycles with great big carbs.


:(

Oh but the joys of not worring about doing back flips when you hit the go-go-go button :) .




Juker008

[Juker008]

Remember you have to run a vacume line back to the FPR and the length will have a lag effect on the fuel pressure. Just do the FPR up front and keep all the lines short. The return line is like dumping fuel to the atmosphere so there isn't any restriction(or not much). ///JT.///


No injectors, thus no modulation of pressure needed, just a constant stream of 16.7 GPH.



Juker008

[techno550]

BTW guys the whole reason why I would like to do it this way is to minimize the ammount of return line that I would need.



Juker008
the fuel still has to go from the tank, to the rail, and back again. how could you possibly make this shorter by moving the location of the fuel pressure regulator?

[techno550]

I should clarify. the fuel goes from the pump to the rail, then to a regulator and then back into the tank. if we put the regulator at the rail, or at the tank, there should be a minimal difference in plumbing length, but only dependent on *convenient* locations for mounting in either case.

The further you are from the rail, the slower the pressure regulators response will *seem* in the rail itself.
The bigger the injector, the bigger the potential pressure drop in the rail. The longer the distance between the rail and the regulator the longer the response time and the lower the response frequency. If you put it all the way back at the tank, you might have a length long enough to set off the system's harmonics via injector firing frequency. If anything, the pressure in the rail will be all over the place. More than what pulse dampers would be able to compensate for. (which should be there anyway, but nobody bothers to run them, even when running large injectors that really would require them to be there to truly function properly.)

[Juker008]

the fuel still has to go from the tank, to the rail, and back again. how could you possibly make this shorter by moving the location of the fuel pressure regulator?

Remember, there is no fuel rail, no injectors. So the fuel doesn't nessesarily have to go to the fuel rail.

Emagine it like this: fuel cell in the trunk, right off of the cell is a fuel filter, then the fuel pump, and right after the fuel pump the FPR. The line that goes from the FPR to the terminal point would be pressurized to the set ammount.



Juker008

[techno550]

Remember, there is no fuel rail, no injectors. So the fuel doesn't nessesarily have to go to the fuel rail.

Emagine it like this: fuel cell in the trunk, right off of the cell is a fuel filter, then the fuel pump, and right after the fuel pump the FPR. The line that goes from the FPR to the terminal point would be pressurized to the set ammount.



Juker008
the "set pressure" area is always in front of the regulator. the regulator regulates pressure at that point by dumping "excess" back to the tank.

the systems that generally have an end point at a fixed pressure and the regulator before it are returnless systems.

[tlmitf]

but, having said all that - there is a car here in australia, the falcon XR6 Turbo, that has the FPR in the fuel tank.

it seems to work, 1000's sold and no poped motors yet (well, not of stock boost ;))