Guages quit working (EA81 electrical question)

[Mike W]

Hey there guys. Mike W here. Damn, I haven't been on USMB in a loooong time!

 

So I recently brought the red Hatchback outa storage. I'm working out a
few bugs and thinking I might finally sell this beastie if I get 
everything proper.

But this minor electrical voodoo issue is
having is driving me nuts and have the feeling I'm missing something
very obvious! I sure hate to post on here but I'm a bit frustrated and
could use help!

 

'88 Hatchback (EA81)

 

All the dash gauges used to work. But recently the Oil Pressure, Batt
Voltage, and Temp gauges...all quit working. But not all at once!  First
the oil pressure quit working, then a few days later the temp guage
quit, then the volt gauge just quit. WTF?!!

 

The fuel gauge and the rest of the dash works just fine.

I can't find any blown fuses.

I've
checked (and sprayed) all connections in the engine bay. All seem fine.
I checked and sprayed connections behind the dash , they seem fine too.

Is there some secret fuse I don't know about?

Bad ground??? Where to look?

Failing voltage regulator? Headlights etc brighten and dim a bit with RPMs and I'm seeing some voltage spikes in the 14.7 range.

 

What am I missing here???

Any help would be appreciated!

Edited November 23, 2015 by Mike W

[Sapper 157]

Have you tried tapping the oil sending unit with a hammer? When mime went belly up it would work again for a short time if i hit it with a hammer.

[Mike W]

Hey thanks that's a good idea! I kinda forgot that sender units can stick. So far I only directed verbal abuse at the oil sender unit. I'll give it some love taps and also do the same with the temp sender unit. I did recently install a new oil pump, reusing the old sender unit. The gauge worked fine then and the oil pressure was good. Pressure still seems good...hydraulic lifters pumped up and no valve clatter.

 

Just seems odd that the temp, volt, and oil pressure gauges quit working almost at the same time. I'm thinking there must be a loose or dirty connection in the harness or something. That or a faulty ground. Anyone else had this happen?

 

I'll be taking the dash apart again next weekend. After cleaning tons of dust out of the cluster last weekend, I noticed that one turn signal indicator bulb isn't working.