1987 Silverado fuel issue

Back to my oil pressure issue. I went to check the wire from the sending unit and I find that it has two wires in the connector, not one, as everybody says it should have if it is a "sending unit" for a gauge. Suggestions?

PS: Last time I started the truck, the gauge was reading off-the-scale high before starting. Then, after starting, it jumped down to reading about 50-60. With the connector pulled off, it reads very high before starting, and then doesn't change after starting.

PPS: Oreillys shows a unit with only one wire in the connector, while I have two. They say that type, with two wires, is for an idiot light, not a gauge. It's a mystery.

PPPS: OK. I see from further reading on this forum, that the unit by the distributor is the pressure switch, and the sending unit for the gauge is down by the oil filter.

This time, after starting, I get no movement from the gauge. it just stays very high. Having trouble getting to the sensor near the oil filter, or even identifying it, for sure.

PS: If I have found it, it seems to be encased in some kind of round, sheet-metal shroud.

PPS: OK... all I did was wiggle the wire, and now the gauge resets to zero and reads close to 60 after starting. Once again, as with the fuel pump, my issue seems to just be poor connections.

87 might be different. My 90 burb has the oil pressure switch and the pressure reading for the gauge all in one behind the distributor.

gmbellew said:

87 might be different. My 90 burb has the oil pressure switch and the pressure reading for the gauge all in one behind the distributor.

Click to expand...

They seem to just stick it wherever they want. My 1989 Suburban has it on the engine block itself just behind the power steering pump.

Nope. It seems there are two on mine. A pressure switch by the distributor which keeps fuel supplied as long as there is oil pressure. That is apparently a backup for if the fuel pump relay fails. Then, there is the one for the gauge, which is down by the oil filter. Sure glad I didn't have to replace that one. It would be a nightmare to remove.

One more crazy thing with connections. My temp gauge was acting up. It would flail about, wildly and then settle on maxed out. I cleaned the connection at the sender and now it reads the temp correctly most of the time. It still flails sometimes, but settles on the real temp.

YakkoWarner said:

They seem to just stick it wherever they want. My 1989 Suburban has it on the engine block itself just behind the power steering pump.

Click to expand...

Are you positive? I think you are looking at your coolant temperature sender. I've never seen a SBC oil pressure switch anywhere besides on the block by the oil filter or behind the distributor. 1 for the gauge 1 for the fuel pump or choke depending on the year.

hamm said:

OK. Thanks. I'll keep that in mind. I have an old ECM which would quit working when it got hot. I already tried putting that one back in and it didn't help, but that was before I found the blown crank fuse. On the other hand, I don't seem to get 12v to the fuel pump connector by the fuel tank when I put 12v to the test lead at the fuel pump relay. That could not be due to the ECM, so I'm still baffled in general.

Click to expand...

Or the old one you put in that you knew was failing popped the fuse.

Ricko1966 said:

Are you positive? I think you are looking at your coolant temperature sender. I've never seen a SBC oil pressure switch anywhere besides on the block by the oil filter or behind the distributor. 1 for the gauge 1 for the fuel pump or choke depending on the year.

Click to expand...

Im guessing they have a big block.

bucket said:

Im guessing they have a big block.

Click to expand...

I thought so as well,not sure that a 2 piece would swap. Gut says it will need trimming

Ricko1966 said:

Are you positive? I think you are looking at your coolant temperature sender. I've never seen a SBC oil pressure switch anywhere besides on the block by the oil filter or behind the distributor. 1 for the gauge 1 for the fuel pump or choke depending on the year.

Click to expand...

Ahh that could explain the confusion then - I have the big block. It definately is the oil sensor/switch (3 wires, 1 to gauge 2 for fuel pump backup).

Ricko1966 said:

I thought so as well,not sure that a 2 piece would swap. Gut says it will need trimming

Click to expand...

Well I put this on the wrong post I was replying about the one piece fanshroud. Not the oil pressure switch. I was confused,I confused other people,other people confused me. There's too dam many broken trucks on this forumn.

Ricko1966 said:

Well I put this on the wrong post I was replying about the one piece fanshroud. Not the oil pressure switch. I was confused,I confused other people,other people confused me. There's too dam many broken trucks on this forumn.

Click to expand...

My broken trucks probably account for 25% of them, lol.