Help Fuel Gauge Not Working!

[DSG_Mach]

Hi guys/gals

My 2003 Mach One Mustang's fuel gauge stopped working a while back and my low fuel light is on in the dash. I haven't really worried about it but the other day I ran out of gas because I forgot I didn't fill the tank all the way last time I got gas. I have searched the forums to see if there are threads on this subject but I didn't find much and the one I did find was back in 2004 and only had 2 replies on it. My friend told me it could be the sending unit that needs to be replaced. I'm not to tech savvy about the fuel system on our cars. I don't know if the sending unit is part of the fuel pump assembly or if its a part by itself? Is it located in the gas tank or near the gas tank? Has anyone replaced one and did it fix the issue with the fuel gauge not working correctly?

I do know the car has an aftermarket Aeromotive fuel pump in it I think its the 340 or 390? Any help is appreciated and I hope to learn about my car more.

Thanks

 

[wmburns]

For the Mustang the fuel sending unit is part of the fuel pump basket located inside the fuel tank. Service will require the gas tank to be dropped. In general the Mustang has an easy gas tank to drop. Recommend getting a new fuel tank filler neck grommet as gas vapors are hard on rubber parts.

The fuel level sending arm is easily bent if not handled carefully. Further the wiper arm resister block could be worn as well. No way to know without dropping the tank to lay a "Mark I Eye ball" on it.

Suggesting. Reset the trip odometer with each fill up. I generally get 275 miles on a tank of gas. So if filled up at 250 miles it's unlikely to ever run out of gas.

Note, there are systems on the Mustang that rely on the fuel level (EVAP for example).

 

[DSG_Mach]

For the Mustang the fuel sending unit is part of the fuel pump basket located inside the fuel tank. Service will require the gas tank to be dropped. In general the Mustang has an easy gas tank to drop. Recommend getting a new fuel tank filler neck grommet as gas vapors are hard on rubber parts.

The fuel level sending arm is easily bent if not handled carefully. Further the wiper arm resister block could be worn as well. No way to know without dropping the tank to lay a "Mark I Eye ball" on it.

Suggesting. Reset the trip odometer with each fill up. I generally get 275 miles on a tank of gas. So if filled up at 250 miles it's unlikely to ever run out of gas.

Note, there are systems on the Mustang that rely on the fuel level (EVAP for example).

I will need to buy a new fuel pump then if I want the gauge to work again? Sorry forgive my ignorance on this subject.
I usually go 180-200 miles on a tank because the car is heavily modified and has aftermarket cams so its thirstier than a normal Mustang. I believe I have an Aeromotive fuel pump just not sure which one.


Edit I found this sending unit at CJ Pony parts this is what I need to buy right?

http://www.cjponyparts.com/fuel-sending-unit-gt-v6-mach-1-bullitt-1999-2004/p/FSU18/

 

[DSG_Mach]

Hi guys I still need help with this. I was looking for the part I posted earlier but they don't seem to carry it anymore. They do carry a Cobra fuel sending unit, can I use this part or will it not work with my Mach One?

http://www.cjponyparts.com/fuel-sen...GraRGjx63G-ZB6ZV5FROsA0CPv7W_oGHQsaAk1k8P8HAQ

I'm guessing I have to buy a new fuel pump and cant buy the sending unit separately? I dont want to have to buy a whole new fuel pump just to replace the sending unit... Any help is appreciated.

 

[wmburns]

Please bear in mind that those of us out here in Internet land can possible tell you exactly what's wrong with your car without a lot more test results. The other problem I see here is that you are "assuming" the problem is in the sending gauge without actually confirming (yes I agree the odds favor that is where the problem is).

It's quite possible to replace just a fuel pump and reuse the reset of the basket. It has already been done once in your car. But the reverse is more difficult since the sending unit is normally part of the basket.

Some of your questions need to addressed by understanding the value of your time. There's a fail amount of work to drop the tank. There's the cost of the new filler neck grommet. There's the cost of re-doing the job if not done right.

I personally HATE doing the same job twice. I would prefer to do the job right one time. Instead of spending $125 for just the sending unit, I would buy the entire basket with sending unit and new fuel pump for $182. or go to Rockauto (about $130).

http://www.oreillyauto.com/site/c/detail/PFP0/A30072/02535.oap?year=2004&make=Ford&model=Mustang&vi=1425013&ck=Search_fuel+pump!s!strainer_1425013_499&keyword=fuel+pump!s!strainer#compatibilityTab_

http://www.rockauto.com/en/catalog/...fuel+&+air,fuel+pump+&+housing+assembly,10147

The advantage of doing it this way is you will have everything needed to complete the job once started.

The other option is to buy the whole basket assembly and then transplant the original fuel pump. That has a high likely hood of success assuming that you are careful. Note, the sending unit is easily damaged as well as not really all that durable in service.

The only way I personally would take the route of servicing the sending unit only is if the car is not a daily driver and i didn't mind having it on blocks for a while. This gives the option to drop the tank and inspect and test everything. Then you will be order parts with a better idea of what's wrong. More importantly you will be able to see if the sending unit will fit.

That's my thought process on the job. YMMV.

 

[erniek70]

I am experiencing the same issue. I actually just had the pump basket replaced (was experiencing intermittent pump failure already), when it finally failed completely. Coincidentally, the gauge was now reading E, and low fuel light on, with a full tank. Now, with everything brand new, the gauge is still reading E. Going through the cluster diagnostics, the cluster is receiving a signal of 255 ohms (full tank), but the gauge shows empty. Is there a fix if the sending unit is working properly, but the gauge, and low fuel light are not? I disconnected the battery for 30 mins, and that did not fix it either. Is that how the ECM is reset? I have read that this issue is not uncommon, but have yet to find an actual fix. 99-04 did not have an anti-slosh module (usual cause of failure on older Fords), so what is it I can do to troubleshoot/fix an erroneous gauge, and warning light, if the signal sent, and received is correct?