I have a 91 vert with about 81K on it. The oil pressure gauge is pegged out to max no matter if the car is turned on or not. So it is time to replace the sending unit. This is the one under the oil filter pedestial. I just need to know some do's and don't from people who have replaced these in the past. So any advice and tips are welcome.

 

it very straightforward. Remove slide on connector. Loosen sender, Remove and replace.

a stubby open end wrench helps a lot. Also, but careful with the water temp sensor.

 

figured it couldn't be to hard. Just didnt know how it was mounted and if oil would go everywhere.

 

Obvious but important: Be certain that the engine is off when you replace it.
Obvious #2: Don't over torque it down - I learned this the very, very hard way.

I thought I had a problem with my sender, but it turned out to be my gauge.

 

A pegged gauge equals the WIRE that connects to the sender is shorted to gnd. Disconnect the wire and see if the gauge is still pegged out.

 

Yep disconnected still pegged, hell even when the battery is disconnected still pegged out.

 

For sure, it's not the sender. Here's the deal. That senders wire has ANOTHER wire spliced to it. That OTHER wire was supposed to be connected to a black colored capacitor. That capacitor is black and square in shape. IT was supposed to be bolted to or near the clutch slave cylinder. The capacitor has a lug on it with a hole so you can do that.

That capacitor had one wire on it with a bullet connector. Is it possible that that capacitor has been removed and the bullet connector has been connected to gnd in some way shape or form?

See the jpg attached. That is what the capacitor looked like. Beware. There is another one dedicated to the igniton coils located under the trail coil area if memory serves. Don't mess with that one. And.........oooops. It seems it does not have a bullet connector but has a connector as seen in the jpg, a spade connector.

Anyway, it was SUPPOSED to be bolted to the clutch slave cylinder.

It might help to add that the wire color should be Yellow/Red or yellow with a red stripe. That would be the color of the wire the plug in the jpg is attached to. So look around under/around the oil filter/sender area for a wire colored yellow/red. The senders wire will be this color also, but your looking for ANOTHER wire of that color in that general area. And it's probably connected directly to a gnd or another thing that is grounded.

 

Yep I know the one you are talking about. That was the first thing I did. Which was pull that ground and clean it. Put everything back and still no joy. So my thinking is that there is a short or open and it fried the sender unit. So my plan was to replace the ground and the sender and see what happens. I still haven't checked the resistance with a volt meter, just lazy and hate chasing wires.

 

Mine was doing the same thing and after reading this thread I poped the hood to find that there was no wire connected to little black spade connector on the slave clylinder. I will replace this today so thanks to you again Hailer! This is why I like this forum.

 

Just in case: If you pull the connector off that capacitor and pull the connector off the oil pressure sender, and then the gauge still pegs out on top, then it has to be a short in the yellow/red wires going to the gauge. Where? Got me.

I'm assuming that if the key is to Off, the gauge reads near zero. You then turn the key to ON or better and the gauge needle travels to the top of the gauge. And this happens when the connector is off the sender and off the capacitor. Is that right? If so there's a dead short on the yellow/red wire.

I've run for yrs without the capacitor connected up at all. Gauge works fine.

An open wire won't cause the gauge to drive to the top. It'll just sit there at the bottom of the gauge.

I'm just writing this to save you the expense of another sender. IF the wire is off the sender and the gauge drives to the top, then it isn't the sender.

 

I'd suggest the wire that SHOULD be connected to the spade connector, is connected to SOMETHING else and that SOMETHING ELSE is going to gnd. Find that connector with the yellow/red wire and disconnect it from whatever it's connected to now. The gauge shouldn't drive to the top anymore.

Like I say, the gauge will work fine if the capacitor isn't connected to the harness. A dead short to gnd on the yellow/red wires, will always drive the gauge to the top.

 

ok, will give that a shot. Right now it pegs to the top no matter what. on off, the ground connected, not connected. I will look for the wires and check resistances on the wires to see if they have shorted out. The reason why I figured it was the sender or the ground was i washed the engine and all of this started. So I figured I shorted one of the two out so I was going to replace them.

 

IF it pegs to the top with the key out, no power on at all..........the needle PROBABLY is stuck at the top. Remove the gauge cluster. Access the Front of the gauges and see if you can pull the needle off and put it back at zero.

 

That could be it, doubt it. right before it went out, the gauge went all over the place. Would say I had no pressure, then way over pressure. So I was going to start with the sender unit and ground wire replacement then on to the gauge, since they tend to fail less than the other two.