Fuel pump

[2011Rangersc]

I just installed the Moddbox fuel pump. My fuel mileage went from 530km per tank to 220km can anyone explain? I will be installing the supercharger in the next couple of weeks.

 

[2011Supercab]

I'd start looking for the leak.

 

[2011Rangersc]

I have no leaks I cant smell gas, run it for a bit and shut it off and it is hard to start?

 

[2011Supercab]

run it for a bit and shut it off and it is hard to start?

That would also make me think there is a leak, the system is losing pressure.

 

[2011Rangersc]

ok I will look. I was thinking too much pressure?

 

[scotts90ranger]

The fuel pump is overwhelming the capacity of the fuel pressure regulator and the fuel pressure in the fuel rail is higher than designed since the regulator can't return enough fuel through the regulator return line, since the computer is assuming a solid consistent fuel pressure which is not correct it's getting too much fuel, if you looked at your fuel trims I imagine they're all pretty low.

 

[2011Rangersc]

Ok, how can I adjust the pressure. I'm going to see my mechanic buddy tomorrow

 

[2011Supercab]

The fuel pump is overwhelming the capacity of the fuel pressure regulator and the fuel pressure in the fuel rail is higher than designed since the regulator can't return enough fuel through the regulator return line, since the computer is assuming a solid consistent fuel pressure which is not correct it's getting too much fuel, if you looked at your fuel trims I imagine they're all pretty low.

If his MPG went from 18mpg to 7mpg wouldn't the truck be running bad?

 

[2011Rangersc]

It seems to run fine feels normal

 

[scotts90ranger]

Ok, I can't guarantee my theory is 100% the case... and even if it was I would expect some type of check engine light from fuel trims...

If the fuel rail has a test port I would check the fuel pressure first thing. Cutting the fuel mileage in half seems like it would change the drivability...

I've seen similar, we were forced to change fuel pressure regulators on some engines at work and the old ones would bypass a whole bunch of fuel and not cause an issue but the new ones if you put a bigger Walbro fuel pump on they'll give out almost 80psi instead of the 60psi they're supposed to but it'll go down to normal when under speed and load, these engines have fuel pressure sensors though so they run fine...