Saddle Tanks

[Karagich]

I have a new 2003 Corvette. I need to know how the saddle tanks fill, does the gas go evenly into both of them, or does one fill and then the other? Is gasoline used equally from each? I appreciate any information anyone has on this. Common sense tells me they fill and empty equally to maintain the balance integrety of the vehicle, but I could be wrong. Thanx everyone. Sarah in El Paso

 

[Rick Daniel]

It is my understanding that the fuel goes into the drivers side and is pumped 50% to the pass. side. As you have already noted this balance's the left to right weight distribution.

 

[Rick Daniel]

Rob,

Does this thread have 523 views and only 1 reply? :eek

 

[HOTMOTORSPORTS]

I think the other 523 as well as myself had to find out what Karagich meant by "saddle tanks"!!!

:confused

Chuck

 

[c4c5specialist]

Hi there,
There is a system, where you fill the drivers side tank, a large crossover pipe lets the right tank fill, after the left one is full.
Now, for the fuel supply system will supply the engine with fuel from the drivers side fuel tank. In order to transfer the fuel from the passenger side tank, there is a venturi pump, that assists in the fuel transfer.
This uses a small amount of bypassed fuel pressure, to start the function of the venturi pump, to suck the fuel from the passenger side, to the drivers.
Your passenger side will always empty first.
A technical side note, depending on your production date, the FFS updated fuel system functions slightly different, and carries different diagnostics.
I hope this helps, c4c5

 

[HOTMOTORSPORTS]

Hi c4c5,

Why would they want the passenger side to empty out first. I would think that the idea of using from both tanks equally would in fact help weight distribution not to mention it would be easier and use less parts than trying to empty one completely before the other. Wouldn't gravity be the best and natural way?

Thanks,

Chuck

 

[c4c5specialist]

HI there,
I do not know why it is done this way, however, it is just the way it is.
Reasoning is unknown.
Allthebest, c4c5

 

[vettepilot]

Just a guess here... Assuming there is always a driver in the vehicle, the drivers side would always be the weighted side and therefore the slightly lower side. Using this as the logic, the drivers side would normally be the side with the lowest point of the fuel tank system, and therefore should always have the lowest point for the fuel pickup. This would, under level driving conditions, give the best useable fuel configuration.
Well that would be my guess as to why it was designed that way, but again it is just my guess.

vettepilot

 

[MacShee98]

The fuel system was designed to balance both tanks, similar to aircraft where there are two tanks, one in each wing section.

The 2002 C5 GM Service manual describes this, although it's not abundantly clear. Yes the right tank pumps into the left, but the left tank pumps into the right tanks "jet" pump or venturi pump intake. That and the return lines have the effect of balancing the levels of both tanks.

 

[HOTMOTORSPORTS]

Thanks MacShee98.

That makes more sense that the fuel in fact does empty out evenly.

Chuck

 

[c4c5specialist]

Hi there, 98,
If you will please reference the diagram attached, you will notice that the siphon jet pump is not opened, but closed, with the suction strainer located at the sides of the pump. Inside this strainer, is the check valves that only allow fuel into the strainer, not out into the tank.
Please understand, function follows form here, so we must remember, that design is alot more than circuit description, and the intricacies of this system are alot more than seen.
Allthebest, c4c5

 

[panrixx]

Hi there, 98,
If you will please reference the diagram attached, you will notice that the siphon jet pump is not opened, but closed, with the suction strainer located at the sides of the pump. Inside this strainer, is the check valves that only allow fuel into the strainer, not out into the tank.
Please understand, function follows form here, so we must remember, that design is alot more than circuit description, and the intricacies of this system are alot more than seen.
Allthebest, c4c5

c4c5specialist

Do you still have this diagram, only it does not appear to be visible. It may have been deleted due to the age of the original post!