Fuel tank sender unit question

keynsham1

Active Member
#3
If the tank is exactly the same shape, which I think it is, then the gauge will be calibrated to read fuel quantity in a similar way but will be set to match the resistance requirements of the gauge. If the V8 and 4 cyl gauge require the same input then there should be no issues. But if there is a different part number then you may need a V8 gauge for a v8 sender unit, and vica versa, as the resistance requirements will be different. I had this issue on an MG Midget years ago. I had an early gauge and a late sender. The gauge only ever read 3/4 full even when the tank was full.
 

colnerov

Well-Known Member
#4
Hi, Because of space constraints the tanks are the same height but the later 4 cyl and v8 tanks are fatter than the early 4 cyl. So the senders indicate level and are also not precision instruments as Harvey points out on numerous occasions.

Colin
 
#8
Hi, Because of space constraints the tanks are the same height but the later 4 cyl and v8 tanks are fatter than the early 4 cyl. So the senders indicate level and are also not precision instruments as Harvey points out on numerous occasions.

Colin
Not joking about precision. Mine stays at "full" for a long time then gradually falls to half way, then plummets to zero. I can only assume it becomes very non-linear due to wear. We really need the reserve tap to judge when to fuel.
 
#11
The fuel gauge on my 75 hasn't worked for a couple of years now & because you have to go into the in-tank pump mechanism to measure resistances & fiddle with the apparently delicate & easily dislodged sender assembly, l haven't bothered with it.
The car does 400-420 miles per tank so l set the trip on fill-up & return to a pump at around 350 miles. So it's handy to know how far you can do on a full tank (l only ever fill the tanks).
 
#15
Thanks for responses so far. The reason I ask is that I’ve mistakenly fitted a NOS 2000 sender unit to my V8 tank. After installation, the gauge didn’t move and I assumed it was due to having very little fuel in. Now, after putting 4 gallons on, it’s still not moving and reading nothing (just as it appears with the ignition off). I need to get underneath and double check the connections but it it’s maybe pointing to needing a gauge off a 2000 as indicated by a previous post?
 
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