My sending unit on one tank is not reading correctly. It is reading near empty and I just put in 6 gallons of fuel. It should be reading 1/2 full tank right now correct? Reads less than a 1/4. I would like to remove the sending unit but not sure when it is safe to remove it so that I won’t have fuel spilling out. I am not sure how much fuel was in the tank before I added 6 gallons of fuel. I am trying to figure out the erratic fuel indications I am getting on my Jag. I am sure I must have a corroded sending unit and would like to pull it out. One other thought that would be much simpler is if I could find an additive that might clean the sending unit so I wouldn;t have to remove it.
Has anyone had any luck with an additive that works?
Lee
Impossible, forget it. Empty the tank and do it right.
Why should I empty the tank if only the sending unit is malfunctioning?
Lee
In the words of the Irish, ‘to be sure to be sure’ I would drop about 4 gallons out then gently loosen the sender unit, it you spy any fuel leaking then drain some more.
As Robin says, Lee; you don’t have to,…
As you had the tank unit out before; how much fuel did you see before you filled the 6 gallons? At 3/4 full it should be safe to remove tank units - but draining off some is safer…
Instead of draining off, somewhat awkward; you could just drive the car to lower the fuel level - there is no real hurry to address the tank unit…?
Frank
xj6 85 Sov Europe (UK/NZ)
Better safe than drenched in fuel, I got close once because I thought it was closer to empty. As Frank says it is awkward but you can just drive it, or take a line from the pump to a container and empty it this way.
I’m in the same situation. I mixed left and right sending unit and need to swap them. Easiest way to find the level inside of the tank is:
Take transparent hose, put it from the top into the tank. Prepare a canister or something on the ground and suck on the hose. Same way you would empty the tank (or steal someones gas). Ones it flows, put your finger on it and hold the end high. Remove your finger slowly and the gas will go back. The hose from the tank to the end must be lower than the tank. Then the level you see is the same you have inside. With that you know exactly at which level it is and if it is save to remove a part.
Robert
Why dont you just drive on that tank until you run out of fuel then switch tanks. That’s what I did anyway.
Don perhaps you are confused at my troubleshooting. I am witnessing some very strange readings with both tanks. Sometimes the right tank reads correctly and sometimes not.
Decided to add 6 gallons or gas to both tanks. The reading should be at least 1/2 full on both tanks. The left tank only measured less than 1/4 tank. Thus I have pretty much decided that the left sending unit needs to be taken out as it seems to be defective.
But now it is a matter of getting the fuel level in the tank below where the removal of the sending unit is possible. I think the sending unit is almost in the middle of the tank is that correct? I will have to look again of where it is positioned on the tank if possible.
Thus I now will have to try to syphon about two gallons at leastn out of the left tank just in case it had fuel in it before I added 6 gallons. Takes time sometimes to troubleshoot when you have no idea of how much fuel is in the tanks etc. The right tank reads now
about 3/4 indicating it had about 1/4 tank. But the reading goes to hell when it gets below 1/2 tank and I checked that sending unit out throughly but may have to pull both of them again. Have to get more serious pretty soon!!!
Lee
Confused. Have you had it out before, or not?
Remove the rear light cluster, Lee; it will clarify unit position and give necessary access to change/remove the unit. The unit is bayonet fitted to the tank - rotate to release - new gasket may be required? …
Your erratic readings are most likely due to the float sticking to the tank walls. As the units are ‘sided’, the wrong side may be fitted, as in Robert’s case - but the float arms may be bent, with the same sticky result. The gauge readings can be adjusted by judicious bending - but if it was done carelessly; sticking may happen…
And like David, I’m confused; checking out misreads meaningfully requires unit removal - which I, and David, assumed you had…
Frank
xj6 85 Sov Europe (UK/NZ)
Thus I now will have to try to syphon about two gallons at leastn out of the left tank just in case it had fuel in it before I added 6 gallons. Takes time sometimes to troubleshoot when you have no idea of how much fuel is in the tanks etc. The right tank reads now
about 3/4 indicating it had about 1/4 tank. But the reading goes to hell when it gets below 1/2 tank and I checked that sending unit out throughly but may have to pull both of them again. Have to get more serious pretty soon!!!
Lee
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You might be dealing with two different issues here. The first is the float has deteriorated over time to the point that it has allowed the ingress of fuel into it causing it to sink down somewhat depending on how much fuel has entered it over time. The second issue plagued my 1987 later series 3 car years ago. The charcoal canister when it became clogged over time, caused the walls of the right (passenger side in the US) to implode somewhat so the float could not make its way to the top of the tank to depict a ‘full’ reading even after filling the tank literally up to the filler neck.
Indeed a factor not to be disregarded. And the extent of deformation is not readily assessed, nor the impact on float movement in such a case…
Frank
xj6 85 Sov Europe (UK/NZ)
The units are sided and depending on the model it can be that someone has mounted the little swimmer on the wrong side. Idiots like me that hasn’t took a picture before dismounting and then mounting back later on the wrong side. Some models have them fixed while the end of the metal is bended. Other models with swimmers looking like a little barrel are hocked in at the end. It can be hooked in from the wrong side. So they never came higher than 1/2 or so and sometimes haven’t moved at all.
The black one is fixed. The bright one can be mounted wrong. I do have those. Wrong picture of model but the mounting principle is the same.