87 v15 Temp gauge & Oil Pressure Gauge

[sandorjoben]

Dear Everyone;

The truck: 1987 v15 350tbi th400
The problem(s): water temp gauge shows nothing, neither does the oil pressure gauge

The oil pressure gauge shows nothing because there is nothing connected to the pressure sending unit by the oil filter (hasn't worked since I got the truck), the wiring in my truck is a mess from POs. I'm probably going to put a new sending unit anyway but I can't find the wire I'm supposed connect to it, what color should it be(Haynes manual says a tan wire but I can't find one) with what type of connector?

The water temp gauge indicated temperature briefly when I first got the truck and put it on the road but then stopped. I put in a new sending unit yesterday and it worked fine for one run but as of this morning I have no engine temp showing again. When the engine starts there is very little needle movement on the gauge(it shakes briefly), I checked the gauge by grounding the green wire connected to the sender and it seems to work(the needle spikes to max temp), I also tried switching gauges with a spare that also passed the ground test and still the same result. The circuit paper for the instrument cluster is also in tip top shape so I don't think that's an issue. Could a sending unit crap out that fast (1 use) or is there another issue?

Thanks tonnes in advance for any assistance.

Dave