Gas Gauge Curfufflal

[Monkeyporn]

Ok Gang I need some help got gas this morning filled tank full gauge only read Half full, BUT as I drove it moved up a little at a time. The needle moved in a not smooth motion but a little at a time like a clock ticking, I'm wondering if my sending unit could be going bad. Not sure if a sending unit goes bad all at once or slowly little by little anyone got any experience with this situation ? Please tell me what I'm looking at to replace and are there one or two pumps ? Do I need to replace both or can I just replace one and how do I known which one to replace ? Also are there any special tools needed ?
I grateful for any help anyone can offer Thanks Gang.

 

[Macman45]

Sounds like sending unit. You only have one pump, but two holes. The drivers side access cover is the pump, passenger side access cover is the sending unit. They are separate so you can just replace the sending unit.

 

[AHaze]

Sounds like sending unit. You only have one pump, but two holes. The drivers side access cover is the pump, passenger side access cover is the sending unit. They are separate so you can just replace the sending unit.

There's a sending unit on both sides.

 

[Monkeyporn]

There's a sending unit on both sides.

Ok So there is a sending unit on both sides so HOW do I figure out which one needs replacing OR do I replace both ?

 

[Dino Dino Bambino]

Ok So there is a sending unit on both sides so HOW do I figure out which one needs replacing OR do I replace both ?

The signal from the passenger side sending unit operates the fuel gauge from E to 1/2, while the driver's side sending unit operates the gauge from 1/2 to F.
It sounds to me like the driver's side sending unit is faulty in your case. That's the side where the fuel pump is too. It's possible the float is merely sticking (perhaps there's dirt causing it) but the other possibility is that the rheostat strip has simply worn due to age, and the only thing you can do there is to replace the whole sending unit.

 

[richie9mt]

Does the 4.0 V6 also have two sending units???

 

[Monkeyporn]

The signal from the passenger side sending unit operates the fuel gauge from E to 1/2, while the driver's side sending unit operates the gauge from 1/2 to F.
It sounds to me like the driver's side sending unit is faulty in your case. That's the side where the fuel pump is too. It's possible the float is merely sticking (perhaps there's dirt causing it) but the other possibility is that the rheostat strip has simply worn due to age, and the only thing you can do there is to replace the whole sending unit.

Hi DINO thanks for piping in I always enjoy hearing your opinion as you have such clear and concise thoughts. Here's the update: I think you hit the nail on the head with your dirt theory, as a day or two later the gauge seem to be working fine. So I'm guessing by me running the tank low one day it sucked up some dirt and when I filled the tank and drove a bit and the gas sloshing around in the tank washed the filter off and thus the gauge began working again......does that sound possible ? Anyway I'm keeping an eye on it to see how it does.

 

[john knox]

get oem or it will not work the gages right, after market do not work

 

[Dino Dino Bambino]

Does the 4.0 V6 also have two sending units???

I believe the fuel tanks, fuel pumps, and sending units are exactly the same on both the V6 and the GT.

 

[Midlife Crises]

There is no fuel on the passenger side below 1/2 tank. It is transferred to the drivers side.

 

[Monkeyporn]

OK so there's been an UPDATE ! I thought it might be dirt on the pick-up filter but after giving it a week and getting gas again the gauge again just went to just passed the half way mark, so its sounds like DINO was right and the driver sign sending gauge has gone bad. That means replacing the whole pump and sender that said anyone got any recommendations of what brand or type of fuel pump I should get ? I love hearing the opinions of you smart mustang peeps it always help me go the right way....thanks Brandi

 

[Racer47]

I think this is backwards....."The signal from the passenger side sending unit operates the fuel gauge from E to 1/2, while the driver's side sending unit operates the gauge from 1/2 to F."

The fuel pump siphons out of the passenger side to keep fuel in the drivers side where the pump is. So I think 1/2 to full is the passenger side, which is the easier side to fix.

Use a multi-meter and measure float resistance of both sides. Add gas or run it low, and re-measure. You should be able to figure out whats going on.

 

[Dino Dino Bambino]

I think this is backwards....."The signal from the passenger side sending unit operates the fuel gauge from E to 1/2, while the driver's side sending unit operates the gauge from 1/2 to F."

The fuel pump siphons out of the passenger side to keep fuel in the drivers side where the pump is. So I think 1/2 to full is the passenger side, which is the easier side to fix.

Use a multi-meter and measure float resistance of both sides. Add gas or run it low, and re-measure. You should be able to figure out what's going on.

Good advice, and it's quite possible I do have it backwards so it's best to check.
The best choice of fuel pump is the '07+ OEM unit (part no. 7R3Z-9H307-C). If you want to upgrade to a higher flowing pump (unnecessary below 400rwhp and NA), the DW300M 340lph is a popular choice. By comparison, the stock V6/GT pump flows 148lph.

340lph Ford in-tank fuel pump w/ 9-1034 install kit

DW300M series, 340lph Ford in-tank fuel pump w/ install kit for 05-10 Ford Mustang V6/V8 (exc GT500)

deatschwerks.com

 

[Monkeyporn]

Thanks Dino question does the DW300S come as a complete pump assembly ? Also what is your opinion of the Walbro 400lph fuel module ? I am still thinking I'll get around to modify to get close to 400 rwhp someday, so if I gotta do this job I might as well get the fuel pump upgrade done now....HUH ? https://lmr.com/item/LRS-9350J/Walbro-255LPH-Fuel-Pump-Module-Mustang-06-09

 

[Racer47]

talk to @JeremyH, he's not around here much but still does pumps. He knows all there is to know about fuel pumps and sells for more than reasonable prices. He's on fb and probably still has a website.

 

[Midlife Crises]

The DW300 is a very good pump with its install kit. I’m running two of them. It does not come with a fuel level sending unit.