Looking for a gas tank and low pressure pump

#21

Why not run both high pressure pumps to a “T” to the fuel rail…that way both pumps only run dry if the tank runs dry.

#22

While that was the solution I used on my E36, I like the “one pump feeds the other” option. The way it looks to me is that the low pressure pump is fed by the return line from the fuel rail and will only not not have fuel to pump during fast, left hand sweepers when nothing (or limited fuel) is coming back from the rail. When that’s the case, the high pressure pump is submerged in fuel. During fast, right hand sweepers, when starvation is commonly occurring, the low pressure pump is submerged and feeding the high pressure pump directly. In a ‘2 high pressure pumps to a tee’ scenario, that high pressure pump is not feeding the other, meaning the un-submerged pump is going dry…and those pumps like to fail when they don’t have enough fuel.

Just my $0.02

#23

The Bimmerworld e36 fix was to run both HP pumps into a “T”. It works and works reliably. Neither pump can go dry until the tank is dry because one HP pump will pump to the other is one goes dry. The pumps have excess volume to cover that. Going to do Wayne’s car that way.

#24

This might be a stupid question but does the drivers side sending unit even need to be hooked up or is it just used because it fills that void in the pump housing? Can’t you just hook up the passenger side sending unit?

#25

The 63 liter tank does not have a cross over tube to equalize the fuel level in the tank halves. With the OE siphon or with a dual pump set up the left side of the tank will have less fuel in it once the level goes below the top oF the hump, except under the G forces of a right turn when the fuel sloshes over the hump. So the right side sensor will generally indicate more fuel is left than there really is as the tank gets depleted. With a sensor in each side, connected in series, you get the average of both sides which is pretty accurate.

#26

I just didn’t know if the sending unit needed to be hooked up or not. If you’re not interested in accuracy.

#27

Well if you never expect to run the tank below half it would not matter. But in that case you don’t need a fuel gage at all.

#28

Great opportunity to Cross-Post…

Want to doublecheck fuel pump part numbers. I want to make sure that this - 16141184022 - is the low pressure pre pump.

Correct?

Thanks.

#29

[quote=“ffej” post=71503]Great opportunity to Cross-Post…

Want to doublecheck fuel pump part numbers. I want to make sure that this - 16141184022 - is the low pressure pre pump.[/quote]
That is the in-tank high pressure pump as used with the 63L tank. The low pressure transfer pump, as used on a 53L tank is part 16141179415

#30

[quote=“jlevie” post=71504][quote=“ffej” post=71503]Great opportunity to Cross-Post…

Want to doublecheck fuel pump part numbers. I want to make sure that this - 16141184022 - is the low pressure pre pump.[/quote]
That is the in-tank high pressure pump as used with the 63L tank. The low pressure transfer pump, as used on a 53L tank is part 16141179415[/quote]

Thanks Jim. Every time I see that part, though, I see a picture of what looks like half a pump or the inline unit. I need the in-tank pump to feed the other in-tank pump that I’m installing (the late model 318is unit) for the two pump solution. Example of why I’m confused: http://www.ebay.com/itm/BMW-3-Series-Fuel-Pump-16141179415-C366-/350510859325

Not that I would buy that one, but I see that more often than a full unit like this: http://www.ebay.com/itm/Electric-Fuel-Pump-for-88-92-BMW-E30-318i-325-325i-325iX-325is-/130861066211

#31

[quote=“ffej” post=71505][quote=“jlevie” post=71504][quote=“ffej” post=71503]Great opportunity to Cross-Post…

Want to doublecheck fuel pump part numbers. I want to make sure that this - 16141184022 - is the low pressure pre pump.[/quote]
That is the in-tank high pressure pump as used with the 63L tank. The low pressure transfer pump, as used on a 53L tank is part 16141179415[/quote]

Thanks Jim. Every time I see that part, though, I see a picture of what looks like half a pump or the inline unit. I need the in-tank pump to feed the other in-tank pump that I’m installing (the late model 318is unit) for the two pump solution. Example of why I’m confused: http://www.ebay.com/itm/BMW-3-Series-Fuel-Pump-16141179415-C366-/350510859325[/quote]
That part is a replacement pump only, not the whole assembly that you need.

That is the full pump assembly, similar to what you need. Though that one is the high pressure pump used with the 63L tank.

The pump can be replaced without replacing the entire assembly. Since that is the cheaper route it is more commonly found on ebay. A competitive source for the pump you need would be http://www.rmeuropean.com/Part-Number/Fuel-Pump-(Pre-Supply-Pump)---In-Tank-Suction-Device-__16141179415_CON_9586A474.aspx

#32

Gotcha. Thanks for the clarification. I was beginning to wonder if it was just a replacement component for the full unit…

#33

Ok, so I have been following along here. From what I can see, this pump is what I would buy to put on the driver’s side (LEFT) and somehow hook this up to the other tank, which mine being a later model with a single pump was not designed for (1989). Does the siphon hose hook directly up to the high pressure pump?

I’m confused on how this is all going to hook up. My car is in the air right now as I swap the clutch and am debating about whether or not I can get this done without dropping the tank.

#34

[quote=“Foglght” post=71522]Ok, so I have been following along here. From what I can see, this pump is what I would buy to put on the driver’s side (LEFT) and somehow hook this up to the other tank, which mine being a later model with a single pump was not designed for (1989). Does the siphon hose hook directly up to the high pressure pump?

I’m confused on how this is all going to hook up. My car is in the air right now as I swap the clutch and am debating about whether or not I can get this done without dropping the tank.[/quote]
It might be possible to snake a line across the top of the tank with it in the car, but I suspect that you will have to drop the tank. You will have to replace the right side pump with one for a late model 318is.

The siphon is in the left side of the tank and the hose from the engine bay carrying returning fuel connects to the siphon on the lower left of the tank.

#35

What is different between the 318 pump and my large tank 325 pump?

#36

The 318is pump has a return line tube that the 325 pump does not have; so in the two in-tank pump solution you can easily run a line from the low pressure pump on the driver side directly to the pump on the passenger side, instead of having to do additional plumbing.

#37

Correct!

#38

So, the return line now goes directly back to the tank on the driver or passenger side?

The new setup would have the return line going to the driver side, with the output of the low pressure pump going to the return line of the passenger side high pressure pump? amirite?

#39

Lots of good information here on using two pumps in the tank.

http://www.r3vlimited.com/board/showthread.php?t=278695

#40

[quote=“Foglght” post=71528]So, the return line now goes directly back to the tank on the driver or passenger side?

The new setup would have the return line going to the driver side, with the output of the low pressure pump going to the return line of the passenger side high pressure pump? amirite?[/quote]

Sort of. The return line from the motor would still plug directly into the tank, you’d plug the return on the low-pressure pump and run a line from the output of the low pressure pump to the return on the high pressure pump.

At least, that’s how I see it working best. Since it’s pretty much Jim’s fix, he can tell you more.

I also think you can do this without having to completely remove the tank and disconnect everything, just lower it enough to get the fuel line from the driver to the passenger side.