82 K10 Gauge Issues, Dual Tank Question

[t44e6]

I have a few gauge issues I would like to troubleshoot, 87 K10. Manual trans, original 305 replaced with a rebuilt 350. First, the voltmeter is inop. What circuit feeds it and where is the easiest place to check that it is getting power short of removing the cluster? Second, temp gauge has very limited travel, and oil pressure gauge barely moves and is basically static at about 20# regardless of speed or load. What values should I measure at the sender outputs? Hopefully I won't have to start replacing gauges.

It is equipped with factory dual tanks and is not feeding from the right hand tank. I haven't dug into it yet, and the Haynes manual I have doesn't really cover it. Where can I find a diagram of how it should be plumbed and wired?

 

[7900_Blazer]

@t44e6

I am by no means a wiring expert… just a novice at best.

As far as the volt meter goes, I think I wired mine directly into a keyed ‘hot’ wire… which should give you the current state of the battery/alternator at all times. The gauge simply takes a 12 volt input.

For my oil pressure gauge on both my 75’ and my 71’, I wanted an exact reading so I updated my mechanical oil gauge with new a new copper tubbing ‘kit’ from LMC truck (and a new gauge for the ‘75). It was pretty inexpensive and not at all difficult to set up. Now I know the exact oil pressure along with every fluctuation.

As far as heat gauge goes, it’s pretty simply, it’s either the gauge, wire shorted somewhere or the sending unit… gauge is cheap to pick up on LMC… and the sending unit is like $6 or something like that at your local parts store, both super easy to put in. I know you said you don’t really want to pull the cluster, but it’s not hard to do, and ‘factory’ gauges look so much better than no-working or after market gauges…

As far as wiring goes, for my 75’ I ordered a color-coded wiring schematic from www.classiccarwiring.com. It’s basically a big laminated poster… super easy to follow.

Dual tanks??? I just saw another thread on something related… I just picked us a 1985 K20 with dual tanks… so likely I’m going to be learning about those as well.

 

[t44e6]

What I was looking for was if someone knew what range of voltage should be coming from the temp / pressure senders and where the voltmeter is fed at the dash so I could get some clues before I started replacing parts or tearing the whole thing apart. I don't consider myself an expert but I did spend close to 30 years working on old Porsches, the last 15 at a world class restoration shop. Most electrical issues are what I call "cabling and connectors". Either the conductor itself is compromised or the connection is bad. Knowing what signal is sent would help me troubleshoot.

 

[1 bad corvette]

I have a 82 Blazer that was converted from a diesel to a carbed 350 gas engine and the wiring was all screwed up. I ended up going to Autozone , spent about 50 bucks and bought some aftermarket gauges and mounted them under the dash. Now I know for sure what my oil, water and volts are. If you don't like them hanging down under the dash, with a little work you can mount them in the original dash bezel. They are almost the same size as the holes for the stock gauges, I believe they are 2 and 1/16 inches in diameter.