Anyone out there that can explain how the fuel transfer is supposed to happen in the saddle tanks? I mean I get that it uses a Venturi effect at the main pump, that causes fuel to be sucked from the passenger side, over to the driver side. Are the levels supposed to stay equal roughly, or not?

Problem 1: I replaced my fuel sending unit from the driver side a while back. I got the error on the dash saying low fuel level, no matter how much was in the tank. Did a bit of checking into it, and the passenger side was full, and the drivers side was very low. Low enough in fact that the engine stalled and would not start again. Played around and took the little rubber "check valve" off the driver side, and now it is transferring, but it sucked everything out of the passenger side. I'd assume those levels should stay roughly equal for the fuel gauge to read, and show a correct level, as fuel is used. If not, it would show full until it has used everything from the passenger side, and then come down quickly, rather than steadily as fuel is consumed.

Problem 2: I pulled both units out to troubleshoot the gauge error. With them both out of the tank, if i move the floats together, in roughly the same position, the fuel gauge in the dash works just fine. As soon as they are in the tank, it gives me that error message. I'm stumped on where to go to figure out why this is happening.

Thanks in advance for any help or theory anyone can provide!

 

Do You Have a Code Reader That Can Pull B-Codes or Body Codes? Might Check For Those. The List is in Here Under Multifunction Modules.

https://themustangsource.com/forums/...0/#post7079673

KC

Here is FORDS Description of How Fuel Gauge Works

Fuel Gauge

The instrument cluster receives the fuel level signal from the smart junction box (SJB) that reads the 2 fuel level sensors. The fuel level sensor measures variable resistance in the fuel tank depending on the current fuel level. When the fuel level is low, the resistance in the unit is low (15 ohms ± 2 ohms). When the fuel level is high, the resistance in the unit is high (160 ohms ± 4 ohms).

The instrument cluster uses 4 different operating modes to calculate the fuel level:

• Key OFF fueling
• Anti-slosh (default mode)
• Key ON fueling
• Recovery

After a fuel fill up, the time for the fuel gauge to move from empty (E) to full (F) ranges from 2 seconds to 55 minutes depending on which operating mode the fuel gauge is in.

The key OFF fueling mode (2 seconds to read empty [E] to full [F]) requires 3 conditions be met:

• The key must be in the OFF position throughout the entire refueling of the vehicle.
• At least 15% of the vehicle's fuel capacity must be added to the fuel tank.
• The instrument cluster must receive a valid key ON fuel sender reading within 1 second of the key being put into the RUN position. The key ON sample readings are considered valid if the fuel sender reading is between 15 ohms ± 2 ohms and 160 ohms ± 4 ohms.

If these conditions are not met, the fuel gauge stays in the anti-slosh mode, which results in a slow to read full (F) event.

The default fuel gauge mode is called the anti-slosh mode. To prevent fuel gauge changes from fuel slosh (gauge instability due to changes in fuel sender readings caused by fuel moving around in the tank), the fuel gauge takes approximately 55 minutes to go from empty (E) to full (F).

The key ON fueling mode (approximately 90 seconds to read empty [E] to full [F]) requires 3 conditions be met:

• The transmission is in PARK (P) (automatic transmission), or the parking brake applied (manual transmission).
• The key is in the RUN position.
• At least 15% of the vehicle's fuel capacity must be added to the fuel tank.

In key ON fueling mode, a 30-second timer activates after the transmission is put into the PARK (P) position (automatic transmission) or when the parking brake is applied (manual transmission). When the 30-second time has elapsed and at least 15% of the vehicle's fuel capacity has been added, the fuel gauge response time is 90 seconds to read from empty (E) to full (F). When the transmission is shifted out of PARK (P) or the parking brake is released, the fuel gauge strategy reverts to the anti-slosh mode. The key ON fueling mode prevents slow to read full events from happening if the customer refuels the vehicle with the key in the RUN position.

Recovery mode is incorporated into the instrument cluster strategy to recover from a missing fuel level input during a refueling event. Missing fuel level inputs result from intermittent opens in the fuel sender or its circuits. Recovery mode (empty [E] to full [F] approximately 20 minutes) is initiated when the following 2 conditions are met:

• The instrument cluster is in the anti-slosh (default) mode.
• The actual fuel level in the tank is greater than what is being displayed by the fuel gauge.

 

I do not. Is there any way to get them without that kind of code reader?

 

Most Auto Parts Stores Will Pull Codes For Free. Call ahead & Ask if Theirs are Body Code Capable! Cheaper Code Readers Only Do P-Codes Which Can Be Helpful But B-Codes Relate To your Issues!

I'm Unaware of Any Alternate Ways To get Those Codes.

Kc