Fuel level in relation to fuel pump question

[turbogate]

Hey Guys, basically, I'm trying to find out at what fuel gauge level do you think that the fuel pump is no longer fully submerged?

I've always have a bad habit of refueling when it's actually time to :biglaugh: (empty light) but I do know that I've been playing with fire. I've indeed noticed that when I do a small run on lower fuel (+-empty(no E light) to 1/8 full), I run dangerously leaner. I never associated it to being on low fuel and always wondered if my AEM EMS was playing tricks on me. I just never thought that running on the lower fuel side of things would make such a difference. It got me to wonder also if the fuel pump (MKIV TT) is not fully submerged, does that affect it's performance as well being that it's NOT running as cool as it can which is why my first question. Don't flame me now, I'm asking because I have just thrown that bad habit away

Thanks

 

[turbogate]

Hey Guys, basically, I'm trying to find out at what fuel gauge level do you think that the fuel pump is no longer fully submerged?

Thanks

Anyone has a general idea?

 

[IJ.]

In a road car the pump can cavitate, usually in a race car the G's are high enough to uncover the pickup when fuel is low and you get a big stumble and switch to reserve.

Sounds like yours is sucking air and this is enough of an interuption in volume/pressure to lean it out, do you have a fuel pressure sender into the AEM?

 

[turbogate]

In a road car the pump can cavitate, usually in a race car the G's are high enough to uncover the pickup when fuel is low and you get a big stumble and switch to reserve.

Sounds like yours is sucking air and this is enough of an interuption in volume/pressure to lean it out, do you have a fuel pressure sender into the AEM?

Thanks for responding IJ. I do not have a fuel pressure sender into the AEM. As a matter a fact I'm still debating whether I should get a seperate fuel pressure gauge (inside car) or just get the pressure sensor for my AIM dash. probably the later

The car runs fine, and nothing bad has happened. I get no stumble etc, I just noticed that the car tends to run leaner when low on fuel and on boost. I was just curious to know by how does AFRs get affected when running low on gas (without running out of gas).

I will never boost while low on fuel ever again :biglaugh: I got away with it to many times already. Especially after I invest in my fuel system (044 or dual walbros). People who usually say that they refill when they reach the halfway mark in their gauge are starting to make sense now

would you say that by the time your fuel gauge shows low (right before the light turns on) the fuel pump itself is no longer fully submerged?

Thanks again

 

[IJ.]

The internal sump in the Mk3 is pretty good but yeah by that stage most of the pump is out of the fuel.

You could input the fuel level from the tank sender into the AEM then have it pull all boost and set a 3000 rpm limit if it's under xx (this is how I'm doing it here as well as tying it into the Trac)

Jays racing stock a really nice filter sock for the 044.