P0303 and fuel gauge droppped out

[StoneTheCrow]

Today check engine light came on so I hit O'Reillys and they got the P0303 on cylinder 3 so likely a spark plug or ignition coil then shortly after on way back to the house the fuel gauge dropped to empty and said something on the display I don't recall what... but it definitely wasn't empty, since it's right down the street I went to the gas station and topped off only took like 3-4 gallons. My question I guess is, are these related? I've been planning on replacing plugs and coils anyway as car has 162,000+ miles and I've only owned it for a few thousand (maybe) of those. Again if there's a thread to go to please point me to it. Thanks.

 

[Dino Dino Bambino]

I don't think the two are related.
The sudden drop in the fuel gauge could be due to either a faulty gauge stepper motor or a faulty gauge sending unit.
P0303 is almost certainly, as you said, an ignition misfire. Use only OEM parts as replacements and avoid the temptation to buy aftermarket coils in bright colours.

 

[86GT351]

I don't think the two are related.
The sudden drop in the fuel gauge could be due to either a faulty gauge stepper motor or a faulty gauge sending unit.
P0303 is almost certainly, as you said, an ignition misfire. Use only OEM parts as replacements and avoid the temptation to buy aftermarket coils in bright colours.

Correct. Sending unit is under the lower back seat.

 

[Laga]

You have two fuel level sending units. One on each side of the fuel tank.
One is connected to the fuel pump. The other is a stand alone unit. It also holds the fuel crossover tube.
If either needs replacement, be sure to use only Motorcraft units with the GREY plastic body. Aftermarket brands with the white body do not work correctly.
I found out about this the hard way.

 

[SVT Rider]

As a easy first step, you can try some Techron fuel additive to a tank of gas.

There have been multiple S197 posts long ago about a sporadic/intermittent fuel level indication due to sulphur corrosion on the sending unit rheostat pickup (mine included, which was resolved with a tank or two of Techron Fuel System cleaner).

 

[StoneTheCrow]

As a easy first step, you can try some Techron fuel additive to a tank of gas.

There have been multiple S197 posts long ago about a sporadic/intermittent fuel level indication due to sulphur corrosion on the sending unit rheostat pickup (mine included, which was resolved with a tank or two of Techron Fuel System cleaner).

I forgot to mention that I had put in a bottle of the Techron cleaner last week, I was wondering if that could've had something to do with the misfire and low fuel alert. Maybe it stirred something up . So you guys recommend Ford coils and plugs???

 

[SVT Rider]

So you guys recommend Ford coils and plugs???

Highly recommend Motorcraft coils over aftermarket.
The Motorcraft plugs are fine, but some favor the aftermarket brands for the 2007 and earlier heads with 2-piece spark plugs. Honestly, the newer Motocraft SP547 plugs for those years is supposed to remedy the issue, so choose what you will.