Hello,

My engine block doesnt have the OPSU installed; instead there is a plug in there which is stripped out and cannot be removed. Somehow i missed this as i was rebuilding the engine. Given the location its impossible to get any type of tool in there to remove it.

Is there another spot on the block i can locate the OPSU sensor and get a reasonable reading from the sensor? Or is there anything else i can do get an oil pressure reading?

thanks for the help!

 

What position are you talking about? Rear china wall or side of the block? You can use either, being a 92 yours would be above the oil filter? Is that stripped out?

 

Im not sure what or where the china wall is. The plug is above the oil filter and is stripped to the point where it wont come out.

If i can use the china wall as a alternative, can you tell me where its at so i can go with that?

Thanks

 

The china wall is the part of the block that meets the intake at the front and rear(under the distributor and under thermostat). The plug near the filter is there as that is an extra oiling port. The OPSU is normally at the top near the china wall.

 

the later cars have the switch combined with the gauge sender and it's above the filter, earlier cars have a pressure switch above the filter and the gauge sender as a seperate unit on the back china wall

 

I have a parts car that was an original z car 305 tpi, and it had the pressure sensor and separate FP cutoff sensor T'd on the china wall. I think that is how most of the earlier cars are as the harness on the car was not cut or rerouted. I thought that only v6 cars had the OPSU above the oil filter?

 

I have several TPI cars and the early ones have the seperate gauge sender on the china wall and the f.p. switch above the filter, the later ones have it incorporated into 1. The sender on above the oil filter will have 3 wires instead of 2.

 

Agreed that the early and later have 2 and a 1 sensor respectively. Could it be that the difference is for export?

 

I should have given details on my car in my first post (sorry about that)
Car was a TBI car but the engine is a 350 crate motor from 86'. The car is now carbed so im not too concerned about the OPSU activating the fuel pump but i want to have an oil pressure reading on the gauge. The wire for the OPSU has three or four wires on it.

If i hook the sensor up to the back of the china wall, will it give me an oil pressure reading on the gauge?

thanks for the help guys!

 

Yes. Whether you put the sensor at the oil filter or at the china wall, they are both oil passages that are pressurized.

 

Great, thanks for your time.

 

I'm very confused now. When I check behind the distributor from the driver side the only hole I see is the hole facing the transmission. I missing something here?

Thanks again

 

Its to the left of the distributor or closer to the brake booster. It may have a pipe plug in it. All the later vortec trucks get there senders put here.

 

this hole where the gold colored pressure sender is screwed in:

 

I found the hole - it had a flush mount pipe plug (1/8 npt) in there as well as a little bit of rtv on it. it came out no problem.

Thanks for the insight and pics guys.

I had bought a OPSU several months ago but the thread is 1/4 NPT, as that is the stock size for a 92. It has the correct connector to attach to the pigtail (3 wires), however all of the opsu's with 1/8 NPT only have a single wire connector.

Can i use any SBC opsu with 1/8 npt thread?
Which of the 3 wires would i connect to the single connector on the opsu?

Car is carbed so i only need a gauge reading, and not send power to fuel pump.

thanks again.

 

On the three wire unit it will be the middle terminal(tan wire). You may be better off getting the single wire sending unit that came on the earlier TPI and SBC motors.

 

the one in my pic is for just a gauge, make sure you get the correct one, they are not all equal (and not for the same psi ranges)

 

I got the single wire sending unit.

Its not hooked up yet (need a 90 degree adapter), but should that tan wire be hot? Currently my gauge is pegged out all the way to the right and im seeing volts at the tan and orange wires.

thanks

 

If i am not mistaken you will see voltage on the orange. The orange is a 12V hot when the key is on to activate the fuel pump if the relay were to burn out(the gray in the three wire plug is to the fuel pump). The tan is to the gauge. Not 100% sure if you should see voltage, but you may. I would think that your gauge would be reading 0 with nothing connected and full when completely grounded to body. Opposite of what you are experiencing. I once had a temp gauge that would get stuck at full when you go to start the car and it does its sweep. Possibly similar issue to what your having?