Over enthusiastic fuel gauge

[cmonSTART]

78 Bus, mostly stock.

Hello folks, my fuel gauge has been a bit wild for a while now. It reads full when the tank is full, but after about 30 miles it swings all over the place when I make right and left turns.. finally after about 80 miles it reads empty.

I opened up the vibrator and it's a thermal type, nothing is visibly/obviously wrong - moves with 12 volts. I was planning on replacing the sender as I have one here, but I'm not convinced that's the issue.

What dampens the needle movement on a 78 so fuel slosh isn't an issue?

Thanks!
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'78 Bus 2.0FI
de K1IGS

[SGKent]

most likely dirty connection, loose wire, or sender going bad. Probably happened to every bus built since inception even though different designs are involved.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Wildthings]

Do a neat job of cutting the access hole and pull out your sender. I think you will find that you get erratic readings as you move the float through its range. Time for a new sender or preferably a rebuild if you are up to the challenge.

[cmonSTART]

Ya, I guess that's the next logical step. The connections and grounds I can access all are good. I'll dig out my 4" hole saw and swap the sender out. It can't hurt - all I have to lose really is a bit of time.
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'78 Bus 2.0FI
de K1IGS

[Wildthings]

[cmonSTART]

Thanks for the help folks. To wrap this up I installed and adjusted the new sender and everything is working great! A 4" hole saw made a nice, even hole and it plugged easily with a 4" chimney plug.
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'78 Bus 2.0FI
de K1IGS

[SGKent]

save the piece you cored. When you have the tank out someday you can weld a metal ring onto the underside so maybe it has a 3/8" lip, then place the cored piece on it and drill some bolt holes. Use those to hold the core in, weld the center hole that the holesaw probably left and touch up. Will look great. The best access plate I have seen here is a square one like that with rounded edges, Factory should have done that when new.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[cmonSTART]

I'm actually a bit surprised that this isn't something that can be readily purchased.

Saved the piece - I'll get around to it someday.
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'78 Bus 2.0FI
de K1IGS