Replacing fuel sender - issues.

[Mark Jefferies]

Hi all.

I replaced my fuel sender in my car and it only reads from 1/4 of a tank to Empty correctly. If I fill the car above 1/4 it stays at 1/4 until the fuel level drops below this point. The reason I brought a new sensor was that I thought the old one was bad (because of the same issue).

I’ve checked the sender outside of the tank and it goes between Empty to Full with no issues.

My obvious thought was that a baffle in the tank has moved and is obstructing the float - but I was wondering if there was a specific way to fit the sender - just in case I’m missing something. Maybe the foot sits inside a channel ?

I don’t want to put a torch anywhere near the sensor hole just in case something bad happens.

Has anyone seen the inside of an SW20 tank -or can tell me how to correctly fit the sender ?

Cheers

Mark.

[GDII]

I don't think there is a baffle around the fuel level sender, only around the pump.

Are you sure it is not the gauge itself gone bad?
It's all based on a resistance system and the variable resistor is the sender float arm moving on the contacts in the sender unit.
If you are getting the exact same issue with another sender then it's not the sender.

Did you test the sender by plugging it in with it outside the tank and moving it and watching the gauge?

[Mark Jefferies]

I don't think there is a baffle around the fuel level sender, only around the pump.

Are you sure it is not the gauge itself gone bad?
It's all based on a resistance system and the variable resistor is the sender float arm moving on the contacts in the sender unit.
If you are getting the exact same issue with another sender then it's not the sender.

Did you test the sender by plugging it in with it outside the tank and moving it and watching the gauge?

Yes the sender was tested outside the pump and worked ok .

It seems odd that something may have moved inside the tank. I’m tempted to have a look inside the tank.- I have one of those remote camera units but obviously fuel tanks are a major concern especially around fumes . Perhaps I made a mistake fitting the sender unit when the tank was low. Perhaps I should have fitted the sender when I had over half a tank (or more) in the car…..

If anyone has had a tank out of a car I’d be interested to know what the obstruction might be.

Thanks for your reply !

[Benckj]

I've had the tank out and took a series of pics. Majority on my repair was focused on installation of a new pump rather than the fuel sender. I did remove the sender and inspect but all was fine as was the tank. I do not recall any obstructions in the tank which would cause sender to read incorrectly. As GDII pointed out the pump has a surge shroud around it but not the sender unit.

I'd guess the problem is with your dash gauge. Why not test your old sender with a multi meter and then connect to gauge to confirm its operational limits?

[Benckj]

Sorry no pic of tank but this is what my sender looked like. Maybe you had a loose wire or the steel rod that possibly interferes with the float operation??