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Every now and then....mostly right after I fill the car up with gas, the fuel gauge in the electronic cluster will display "FFS". Usually, it will only show this FFS for a few minutes and then it will revert back to it's normal display (Trip Distance, Fuel remaining, etc.).

What does the FFS stand for?

What is causing this FFS to be displayed?

Is it a problem....or is it just something normal?

Should I take some kind of preventive maintenance action to preclude a bigger more serious problem later on?

I have searched for these answers already, but could not seem to find the specific information. Any other thoughts or comments are welcome....

By the way, here is a picture of my 91 Cougar:

 

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If you ask anyone (including ford) you will get the blank stare and be told the car is too old and they don’t know (3 ford techs and 2 ford fuel system engineers later). The answer (seemingly unobtainable elsewhere) is the fuel system is, for no known reason, upchucking a lung at that moment and the system isn’t capable of determining flow rate. The “FF5” as it shows in the display is actually referring to something that doesn’t exist in the car, a ‘fuel flow sensor’. Ford strikes again.
 

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Discussion Starter #3
If you ask anyone (including ford) you will get the blank stare and be told the car is too old and they don’t know (3 ford techs and 2 ford fuel system engineers later). The answer (seemingly unobtainable elsewhere) is the fuel system is, for no known reason, upchucking a lung at that moment and the system isn’t capable of determining flow rate. The “FF5” as it shows in the display is actually referring to something that doesn’t exist in the car, a ‘fuel flow sensor’. Ford strikes again.

tbirdbrain,

Thanks for the quick reply.

So....are you saying that there is nothing really wrong with the fuel system since a 'fuel flow sensor' does not exist in the car? If so, what component is triggering the "FF5" to be displayed?

Is there anything that should be (or could be) done to correct this anomaly?

Appreciate your thoughts....
 

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There seemingly is no fix for this spurious and intermittent issue. The fuel flow is a hypothetical calculation derived from the injector pulse width (duty cycle), pulse count/time & number of cylinders. This is all handled by the ecu and is outputted as a low speed serial data stream to the cluster. I haven’t found any direct cause to, or cure for this problem. I’m afraid we are on our own.
 

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Discussion Starter #5
There seemingly is no fix for this spurious and intermittent issue. The fuel flow is a hypothetical calculation derived from the injector pulse width (duty cycle), pulse count/time & number of cylinders. This is all handled by the ecu and is outputted as a low speed serial data stream to the cluster. I haven’t found any direct cause to, or cure for this problem. I’m afraid we are on our own.
Wow….that was quite the “detailed” answer !

I was hoping for something more like just changing out the fuel tank pump/sending unit, etc.

I have owned this car since new and it currently has ~ 181,000 miles on the clock. The car still has the original fuel pump/sending unit installed (....although it could be on it's last legs). So, you don't think swapping out the fuel quantity "sending unit" would make any difference ?
 
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