Fuel Tank Sending Unit

[leomosley]

The fuel gauge on my 05 Echo has just started to react very slowly. I filled the tank a few days ago, and it took about 20 KM's of driving for the gauge to move from near empty to full. Now after about 170 Km's, it dropped two bars on the gauge all at once. This happened all of a sudden, and I haven't done anything to the vehicle other than add fuel. I gather the fuel sending unit, filter, and pump are all accesible from an access plate under the back seat. I have found info and pictures of the filter and pump, but nothing specific about the sending unit. Does anybody know if it is attached to the filter and pump assembly, or is it a separate piece in the same area? From what I have found, a Denso Part # ND1748391 seems to be the sending unit. Anyone know if this is correct?

Thanks for your help!
Leo

[ericlp]

I would check the rubber gasket on the gas cap. If the pressure is not there it could effect the sending unit to the gauge.

First thing replace gas cap gasket drive it for a few days and see if your problem doesn't go away.

Next, I would check the fuses for the sending unit...

Then I'd take a look at the fuel pump and maybe replace the sending unit if it's replaceable?

http://www.michaelchow.com/techinfo....f/fpr/comp.pdf

[leomosley]

Hi Ericlp

Thanks for the tips. I am pretty sure the fuses are OK. I only see two listed that have anything to do with gauges, and they both also cover other items that work OK. I checked the gas cap gasket and it looks fine. I cleaned it and the mating surface up and put some silicone spray on the gasket. I 'll give it a try and go from there.

Thanks again!
Leo

[leomosley]

Hi Ericlp

Just wanted to let you know that my Fuel Gauge is working great now. I'm guessing that the Gas Cap Seal was the problem. It seemed to take a few kilometers to sort itself out, but than the gauge started following the level down correctly, and after I filled up today, the gauge went right up to full.

Do you know what the connection is between the Fuel Level Sender and the Gas Cap sealing correctly? I have attempted to sort it out in my mind, but I can't figure out the connection.

At any rate, Thanks very much for your help. I would never have thought of this.

Cheers
Leo

[ericlp]

Aloha Leo,

Glad your Fuel gauge is working again! Your welcome. I think the problem is if the gas cap doesn't seal correctly it loses pressure and you can see that there is a vapor pressure sensor next to the sending unit guage. I'm sure that the computer measures the pressure of the tank to get an accurate reading of the gas level in the tank.

Glad to have helped you out.