Spastic 80's fuel gauge

[Subzilla]

For years, my Sub fuel gauge has always had a "floating" needle depending upon the bumps in the road - no big deal. But over the past couple of weeks, the needle will go spastic and will jump from 9 o'clock to 3 o'clock and every in between at random. It does not do it all the time. Is the sender going bad or could it be the gauge itself? During the non-spastic movements, the needle still accurately reads the fuel level. So I'm wondering how long it will still function.

[DmaxMaverick]

While it could be the sender, or wiring anywhere between the sender and gage, it's likely the PCB (Printed Circuit Board) the gages plug into. Cracks and flaky connections are common after all these years of service. I had to "overhaul" the PCB in my '85 when it was 10 years young. Lots of off-roading and bouncing around took its toll. The gages and lamps are suspended in the board, and the board supports all the mass. It's free to check it (only your time is required), and a lot easier than dropping the tank. If your gage ever flakes out, 99% of the time it can be fixed for less than $10 in 20 minutes. Check out www.fix-a-gauge.com (http://www.fix-a-gauge.com).

[Subzilla]

So you're saying the fix-a-gauge solution should fix it?? Or are you saying I should give a good look at the circuit board?

The funny thing is I just noticed my Blazer starting to do the exact same thing!!! Whatsup with that?? The vehicles must be related.

[DmaxMaverick]

I don't think the fix-a-gage will help you with your current issue. I just threw that in for future reference. Most of the time, the indicator the fix-a-gage will work is when your fuel gage doesn't read above 1/4 tank. Very rarely, the gage will work intermittently for a period before it fails.

Yes. Get a close look at the PCB. Carefully. Got no idea why your other vehicle would be doing the same thing, at the same time. The only common element between them is your fuel of choice. Correct? Unless you have both with the same brand and age senders (perhaps a fuel chemistry issue), I have no idea how they could be tied into the same cause. Coincidence or fate....choose your poison.

[Subzilla]

Yea, I thought about the biodiesel element and wondered if that hasn't done a number on the senders. I've been using about 75% BD for the last year or so in both vehicles except for winter when I run 25%. I haven't heard of any other BDers having this issue. Maybe I'll post it over on that forum.

I'll eventually do some exporatory surgery but right now it's low on the priority list. I was hoping it could be an easy fix.

Thanks for your help.