i gotta silly question for anybody that wants ta answer it. I have a 92 sierra c1500/5.7, mileage unknown, and the oil sending unit by the oil filter isnt plugged in but yet it will show that i have some pressure at times then none the rest of the time. why is that??

 

Electric gauges vary at where they sit when the engine is shut off (no power).....so I guess its a similar thing

Plug it in and see what it does

 

Is this 5.7 a new used engine in your truck?
Is it possible the engine wiring harness get a little messed up during the install?

 

engine is used,and as far as i can see tha wiring harness,at least acording to tha wiring diagram, all in place, but i cant seem to find any wiring/plug to hook up to that sending unit. ohh and if i didnt mention it before(sorry for tha lack of info) tha gauge does flucuate at times when i rev it up. tha oil and filter is up to par( just changed them 3 days ago)and there is no knocking either. my next step is to install a mech gauge. it just got my curiousity a flowin why it would do what it is doin. just went back ta double check everything out again and i noticed that tha sending unit on to behind tha distributer isnt a single wire sensor like tha one i seen in a post earlier lastnite. cant remember which one it was, very late and could focus very well. too much enterweb lastnite i guess.

 

I guess you dont have the sending unit from your old engine.....If you do, see if it will screw into that hole behind the distributer