Fuel Level Sensor Investigation - Ford Muscle Forums : Ford Muscle Cars Tech Forum
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post #1 of 9 (permalink) Old 11-12-2009, 05:25 PM Thread Starter
Join Date: Jun 2004
Location: Northern Utah
Posts: 864
Fuel Level Sensor Investigation

Ok since I am having issues with my Fuel Level sensors I decided I needed to see what they were and how they were put together.
Ford claims that buildup of Sulfur on the contacts is causing the FLI errors and the erratic gauge issues.
So to do my own investigation I jumped in to see what I could see.
Here we go:
First remove the rear seat lower half and set it aside.
And remove the plastic cover over the tank sensor.
Just pulls off.
Here is what you see:

Next step is to unplug the electrical connector and remove the lock ring from the sender unit. Just use a drift and tap the lockring CCW to unlock it and remove it.

The Sender assembly is spring loaded and may pop up slightly when the ring comes off. If not just wiggle it a little to free it from the o-ring seal between the sender and the tank. There is a fuel line (Crossover tube) connected to the assembly. This will need to removed before you can pull the sender out of the tank. To remove it push in on the green tab while pulling on the fuel tube connector. Push Hard to get it to release. Here is a picture with the tube released and sender assy out of the tank so you can see it better.

After the tube is disconnected just carefully maneuver the sender out of the tank. Be careful of the Float attached to it.

So here is the assembly out of the car.
The Sensor is the white plastic item on the assembly.

To remove the sender simply remove the small screw at the bottom and gently slide the assembly up off the sender assembly. You will see how it comes off no problem.

This is what you will get:

Next on to what make this tick.
We need to spread some plastic ears slightly to get the cover/coil to separate from the mount plate it is on. Be careful because they can break very easily.
The Float and cover come off and we can see how this thing works:
(Sorry the picture isnt so great)

The float is connected to a plastic part that holds a contact against the variable potentiometer (Coil). As the Float rises and falls it varies the resistance on the coil.
You can remove the float to disassemble the contact from the assembly. It is held together by ears like the body. Just tap the protruding shaft to unsnap it from the ears. Careful again as they can break really easy.
Here is the disassembled unit:

Here is a poor picture of the moving contact:

I took a pencil eraser and cleaned off the coils and the sprayed it down good with MAF cleaner.

The coil seemed to have a lot of wear on it where the contact was riding on the coil. So I also slightly bent the contact so it touched on a different path.

Reassembly is just reverse of removal.
I put all back together and put it back in the tank.

Seems to be working so far. Time will tell for sure.
The Drivers side is the same setup but of course has all the pump components too.
I didn't remove it as my problem seems to be on the Full side of the tank level.

Pretty simple setup but not really reliable as history has shown so far.
Hopefully Ford improved the design and made it more robust.
But now we know how it works and what it looks like in there.

IMO the Sulfur claim could be bogus. I think it is wear that is causing the problems.

Rich Sr.

Good luck with yours and hope this helps someone out a bit.
ixtlan is offline  
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post #2 of 9 (permalink) Old 01-06-2010, 09:29 AM
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Re: Fuel Level Sensor Investigation

ixtlan, great info and thanks for
taking the time to share it with
hammeron is offline  
post #3 of 9 (permalink) Old 01-08-2010, 09:58 AM Thread Starter
Join Date: Jun 2004
Location: Northern Utah
Posts: 864
Re: Fuel Level Sensor Investigation

Just an update to this.
The gauge started acting up again, and I pulled the sensor to check it out.
The contact made its way back into the groove it created the first time.
So new parts on order.
Ford discontinued the separate sensor option so I got to buy the whole passenger side unit.
Driver side is still available and I got that in hand.
Design is different so hopefully the problems will be solved for good.

Rich Sr.
ixtlan is offline  
post #4 of 9 (permalink) Old 01-08-2010, 02:06 PM
Join Date: Apr 2009
Location: Reno, Nv.
Posts: 55
Re: Fuel Level Sensor Investigation

Simple solution to the problem.
Don't dissect and play with parts that you don't have any training, skill experience, knowledge or certification in ( because this is a federal emission item) because this will only cause you in the end, to buy new parts from Ford, to replace the ones you played with.
Take it from someone who owned and operated an auto repair business for over 20 yrs on all makes and models of cars.
You mentioned using a drift and tapped the lock ring out, never once did you mention safety,, that gas tanks are extremely explosive, and a spark from using the wrong tools can cause an explosion that can kill.
Backyard mechanics cause themselves more grief, and costly loss of homes and lives by not seeking out a certified mechanic or business for advice or repairs.
I hope your new part you bought works for you.
Hope this helps or saves someone out a bit.

Have Pony will travel
PonyGirl1969 is offline  
post #5 of 9 (permalink) Old 01-08-2010, 03:35 PM
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Join Date: Sep 2004
Location: Sunny Arid Desolate Port Orchard WA
Posts: 34,851
Re: Fuel Level Sensor Investigation

Come on PonyGirl, relax a tad, since when is the fuel gauge a federal emission item?

About the spark and proper tools for that you're spot on, but then again, this entire sight is nothing but Back Yard Mechanics like me (Even though I'm ASE Certified in several fields), I am still a Backyard Mechanic when it comes to many things, like rear ends and race motors and the like...

There's nothing I can't do if I ask the right questions...
FEandGoingBroke is offline  
post #6 of 9 (permalink) Old 01-08-2010, 04:31 PM
Join Date: Apr 2009
Location: Reno, Nv.
Posts: 55
Re: Fuel Level Sensor Investigation

Ok,, Ok,, so I'll try to relax... maybe...
You have no idea how many Mr Fix It's came to us as customers and couldn't understand how they had to finally replace their parts that they "fixed" themselves or from a buddies advice, with new parts. And yes, I'm big on the safety issues that go along with all car repairing, having lived with our business burning halway to the ground from one of our Mr Fix It's car repairs torching it when it was pulled in.
So I'll try to chill out for now...

Have Pony will travel
PonyGirl1969 is offline  
post #7 of 9 (permalink) Old 01-08-2010, 04:38 PM
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Posts: 461
Re: Fuel Level Sensor Investigation

Anything to do with the fuel system is under emission requirements, carbs, pumps, return systems, evap systems, etc, just like anything with exhaust systems. More and more everyday. Now all new cars have tire PSI sensors to tell you the air PSI is wrong, and there is no room there for some chalk reading either. And that little computer in the car records everything that's done to that car. Dealerships and insurance companies download it all the time. Having that ASE is always a good thing and makes you a more creditable tech rep here. If I told you to just take a pry bar and pry the coil springs out of your car, cause it worked for me, or just take the nut off the springs of your struts, what would you think.
Safety is obviously not a consideration at this garage, even if it is at home. Maybe that's why most fires in the private home start in the garage. Look around your garage sometime, how much, old paint, fertizilar, compressed air is nice too, oils, gas can, spray cans and other objects that burn and put off posion gas, are stored out there. Even anti freeze will burn. And if you own any firearms, how much ammo or gunpowder do you keep around? Anyone have any welders? And if you do have this stuff at home and something happens, your home owners insurance probably won't cover it either, unless you're insured specialify for it.
How many of you even have a fire extinguisher in your home? My dad kept 1 in each on the corners of the garage (4) and installed his own sprinkler system. Made the insurance go down for the home too.
This looks like an accident looking for a place to happen. Probably puts gas in the lawn mover while it's running too.
If you're going to advise people or show them what you're doing to "whatever", safety, first, last and always. It's called professionalism or in some cases common sense.
rickyracer is offline  
post #8 of 9 (permalink) Old 07-17-2014, 07:16 PM
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Join Date: Jul 2014
Posts: 3
Re: Fuel Level Sensor Investigation

I just bought a one owner 2003 Mustang 3.8l auto with 29,000 original miles from my mother in law. Talk about a perfect car. However today the check engine light came on and it is the fuel sensor. I am not shockef as the gas gauge was acting odd. Outside of not having a correct fuel gauge reading us there any problem with not fixing it right away?

New stang owner
Trump151 is offline  
post #9 of 9 (permalink) Old 04-16-2015, 05:33 AM
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Join Date: Apr 2015
Posts: 1
Re: Fuel Level Sensor Investigation

Does anyone know how "direct fit" this universal unit is?

HWE3 is offline  
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