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2016 Jazz Blue A8 Scat
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Discussion Starter #1
I thought this was interesting. I was wondering how all this stuff worked together. The venturi thing is a surprise.

Auxiliary Fuel Pump Module & Main Fuel Pump Module
Courtesy of CHRYSLER GROUP, LLC
This vehicle uses a saddle type tank that has a reservoir on both sides of the rear drive shaft. The main fuel
pump module (2) is located on the left side of the vehicle. The auxiliary fuel pump module (1) is located the
right side of the vehicle. The fuel outlet or fuel supply line is on the auxiliary fuel pump module (right side) and
supplies fuel to the engine. The electrical connector is on the main fuel pump module (left side) and controls
both modules. The fuel pressure regulator is integrated into the auxiliary fuel pump module and is not a
serviceable component.
Both modules have fuel level sending cards. The fuel level sending cards are not serviceable components. There
are two hoses that connect the main and auxiliary fuel pump modules together, one is the fuel supply line the
other two are fuel return lines. These lines are removed from the main fuel pump module when servicing either
unit. One fuel filter is used and is located at the bottom of the main fuel pump module and is designed for
extended life. A separate frame mounted fuel filter is not used with any engine. The fuel filter is not a
serviceable component.
Fuel enters the reservoir of the main fuel pump module (left side). The main fuel pump module (2) pumps the
fuel through the filter to the auxiliary fuel pump module (1) (right side) through a supply line inside the fuel
tank. The fuel pressure regulator inside the auxiliary fuel pump module regulates the pressure at 58 psi and
sends fuel to the engine. All unused fuel that is not sent to the engine is fed through a venturi at the bottom of
the auxiliary fuel pump module. This creates a low pressure siphoning effect and draws fuel from the passenger
side of the tank and transfers it to the drivers side tank via a siphon hose inside the tank. While the vehicle is
running the fuel in the right side of tank is continuously transferred to the left side. Fuel will continue to fill the
left side tank till it reaches the bridge section and then starts to spill over to the right side.
Both main and auxiliary fuel pumps have fuel level sending units and the reading of these senders are averaged
out to give the fuel gauge reading. When diagnosing a fuel level sender concern, the right side reading should
never be higher than the left side reading. However, it is possible, depending on fuel level and driving habit
before diagnosing, to spill fuel over to the right side that might indeed show a lower resistance value than the
left side.
The fuel gauge gives an indication to the vehicle operator the level of fuel in the fuel tank. This fuel gauge is
controlled by the instrument cluster circuit board based upon cluster programming and hard wired inputs
received by the cluster from the fuel level sending units integrated into the fuel pump modules.
 

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The Pork Wagon (‘14 Cop Charger)
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7,358 Posts
Good to know the working details of the two-system in these cars.
 

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2018 Dodge Challenger T/A Plus in Yellow Jacket w/5.7L and A8 automatic
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