Oil gauge issues

[static_86]

Hey guys been on the forums for a while but this is my first time really posting.

I know the oil gauge is a well covered subject. I have been reading every possible thread and haven't come up with a solution yet.

The truck is a 1986 gmc 1500 original carbureted 305 with electric choke

I'm currently doing a 402 big block swap and have had an issue with my oil gauge

Since I've owned the truck the gauge has never worked for me always been at 0psi. Engine ran good and oil was always kept topped up so I never had an issue with it. Now that I'm wanting to start this big block I want to know if my engine is making proper pressure.

Ok so I got a new oil sender screwed it into the block. And took the single spade wire and connected it to that. The other 2 prong - 3wire connector that operates the choke is left unplugged.

When I turned the key to the on position nothing happened it remained at 0 but when I ground out the wire. Nothing happened. Fearing gauge problem I now have the cluster out. I cleaned all the contacts and the board and now when I turn the key to the on position it just pegs to max pressure.

If I disconnect the lower terminal on the gauge it goes back to 0 but then when I ground the wire it remains at 0.

I disconnected the wire at the sender and verified there's voltage there


I'm really stuck here and just want the oil pressure gauge to function.

Sorry for the long write up but any help would be much appreciated

 

[deanobigred]

I am new to this my, first build I will be checking my pressure this weekend, I have a 85 k1500 with a 327 that being said my gauge is pegged out , my brown wire to this oil pressure sender reads 8.5 v with the key on but not started.
these are facts I don't know if they are what they should be but my guess is that my sender does not match and the 327 needs a better sender, you can buy a gauge to check your pressure cheap and that's the way I'm going to be sure, I will post when I finish my diagnostic. again while I have worked in industrial maintenance all my life this is my first build, if I can help I will but there are plenty of people here that know way more than me.

 

[static_86]

I think I just figured it out. The brand new sender I got was bad out of the box. Got a working sender and the gauge seems to be good now. If it's pegged chances are you have a bad ground

 

[chengny]

And use no (or just one turn) of teflon tape on the threads - the switch internals are grounded through the body and then into the block. Same for the coolant sender. Also the choke heater on a Q-jet is grounded through the carb body.