Fuel pump running but no rail pressure

[upallnight]

Originally Posted by g300d

Uh oh, there's fuel at the pump side then.

I guess it's time to check for fuel at the fuel filter inlet?

I would think that there should be more than 4L of fuel in the right tank since the fuel pump is located in the right tank.

You can jack the left side up and see if some additional fuel gets transfer to the right tank., or you can just buy a couple of gallons of gas and dump it into the car since the right side normally fills up first.

[g300d]

On E53's, most of the fuel is in the left tank.

I've seen splits like those monitoring my own fuel system, doesnt seem out of line.

I've experienced transfer pump problems on a 4.6, it would run out of fuel at about 1/4 tank. At stall/no start, fuel at right tank was zero.

It would still run/start fine at 1 liter and even below, though.

[upallnight]

Originally Posted by g300d

On E53's, most of the fuel is in the left tank.

I've seen splits like those monitoring my own fuel system, doesnt seem out of line.

I've experienced transfer pump problems on a 4.6, it would run out of fuel at about 1/4 tank. At stall/no start, fuel at right tank was zero.

It would still run/start fine at 1 liter and even below, though.

Why is this since the filler pipe is on the right side of the tank?

[g300d]

The right tank is smaller than the left, and as the fuel pump sucks up fuel the excess gets pumped to the bigger left tank, which the transfer pump then moves to the right tank.

Smaller tank right tank gets used up quicker, and replenished slower from the bigger right side.

That's how I understand it based on personal experience and info I've come across.

[cn90]

How much fuel in the tank?
If less than 1/4, then probably from bad siphon pump.
Put fuel in above 1/2 and go from there.

[Pepsimax]

there was 40L in which means aprox 1/2 tank. I filled about 10 l on the tank to be sure but it still didnt start until I used start gas... and voila.. it runs.

the problem is I'm not sure why it runs now.. as I've attempted all of this before. Dont trust the car now and drive around with a spare tank of gas just in case it has to do with transfer pump.

Will update after I've used it a few days.

[upallnight]

Originally Posted by g300d

The right tank is smaller than the left, and as the fuel pump sucks up fuel the excess gets pumped to the bigger left tank, which the transfer pump then moves to the right tank.

Smaller tank right tank gets used up quicker, and replenished slower from the bigger right side.

That's how I understand it based on personal experience and info I've come across.

Not according to this diagram from this poster.

http://www.xoutpost.com/1039858-post5.html

[g300d]

Originally Posted by upallnight

Not according to this diagram from this poster.

http://www.xoutpost.com/1039858-post5.html

Isnt the left tank (where the filter is) bigger in the posted pic?

Anyway, checked tank capacities and:

3.0:


4.6:


What does your OBC test 6 look like?

[upallnight]

Left side of the tank is larger, but the right side of the tank get filled first and the extra gas spill over into the left tank side. The transfer pump is always running as long as the engine is running so the left side of the tank tank is constantly filling the right side of the tank and any extra gas once the right side of the tank is filled is spilled back into the left side of the tank.

The problem is when the transfer pump is not working so the right side tank is not filled with gas from the left side, but the fuel pump is on the right side, so all the gas in the right side eventually is used up, but the left side still have gas.

[g300d]

Re-reading my post, it may not have been clear.

Yup, the smaller fuel pump side gets filled first, around 25liters IIRC.

Excess spills over the hump to left side.

Fuel flow starts from right tank, to fuel rail, then to return line discharging to the left tank.

But eventually most of the fuel ends up on the left when I monitor the OBC.

It seems the left tank always has more fuel than the right tank with these two X's, and it seems the OP's X is the same?