Okay, finally got around to doing some testing. Tested the fuel pressure under both conditions and it varies by 3psi. It is 42psi with the inline pump off and 45psi with it on. I am not sure if 3psi is enough to effect your idle, but I am guessing the stock ecu/maf is a bit more sensitive to that sort of thing.

 

Any Pics ... ??
My Inline pump will be mounted this week end ... Im crossing my fingers ..

 

Here's a few pics

 

your pump looks bakwards

 

I set it up that way, because the lines fit better crisscrossing them, than trying to run them direct from that angle. They crisscross under the IC pipe. Of course if I had it on backwards there is no way I could push 530whp on E85

 

Is this before or after the FPR with it plugged or open? Just trying to get the specifics to see if we can nail down what is truly happening.

 

I have a fuel pressure gauge on my regulator, which comes off the passenger side of the fuel rail. This basically measures the fuel pressure in the rail, so 42psi with the inline pump shut off and 45psi with it turned on.

I am not sure what you mean by plugged or open? The fuel pressure regulator has the vacuum line attached if that is what you meant. I do know you are suppose to set base pressure without the vacuum line attached, but I just wanted to know the difference between the pump being on and off. I think pulling the vacuum line off causes the pressure to rise a few psi if I remember correctly.

 

Your engine's fuel flow requirements at idle and steady state cruise are much lower than at W.O.T. A Hobbes switch is normally only employed in a parallel dual pumper setup. With a parallel double pumper, the primary pump does not have to push through the secondary pump. The 044 pump in your inline setup may well act as a flow restriction depending on its internal design.

 

I have heard many times by many people that an inline pump doesnt cause a significant restriction in fuel flow when not running. The main advantange I see to turning off the 2nd pump is the lack of huge current draw at idle.

 

Do you know exactly at what boost pressure your 044 pump is kicking in at? How can you tell when it switches on, or are you just guessing? I am assuming that you have a fuel pressure gauge installed, right?

Via your Hobbes switch you are able to adjust the point at which your secondary pump acivates. So, by adjusting it to kick in at 1# of boost you can test out the theory that it is acting as a restriction when it is off.

 

Makes sense now...

 

@ justa4banger : Actually I have The Sensors of the Water Injection EXACTLY the same place where ur inline is :s :s ... Do u have any idea ??? Or its better to be In the Trunk for example ?

 

Yea, I use my AEM to switch it on at 5psi. If I want it to be always on I just set the boost param as low as it will go (-14 or so). I tried setting it at like 12psi, but that is not soon enough, I end up hitting a lean cut. I can also add other parameters as well like throttle position.

I understand the parallel double pumper setups and they will outflow mine easily, but they are a bit pricey. I might have no choice though, If my pumps can't keep up once I get 2000cc injectors.

As far as the pump being a restriction, either psi drop is due to the Bosch pump being stronger or the Bosch pump interrupting the flow. Even if the 3psi drop was due to the flow being interrupted, that isn't that big of a drop.

The only other way to tell for sure is to remove the 044, and see if my base pressure is greater than 42psi.

Restriction or not, the only surefire way of knowing if this setup is detrimental to either pump is to keep running it over time.

 

What are the reason for running a 044 in series vs another Walbro parallell in tank? Will a 044 in serie with a Walbro give more fuel vs 2 Walbro in parallell?

 

nice question , +1 ...