Oil Pressure "PINNING"

[JDA1953]

Hello all

As a new (old) motor boat owner I am preparing a recent purchase for use. The only thing remaining (at the moment) is that the Oil Pressure guage "pins" as soon as the ignition is turned on. It stays pinned, at the maximum level until the power is shut off, regardless of whether or not the motor is running. The motor seems to be running OK for it 870 hours, and the oil appears fine, etc. I've changed the sending unit and nothing has changed on the guage. Any suggestions as to what to try ?

Dave

 

[Barnacle_Bill]

Re: Oil Pressure "PINNING"

Disconnect the sending unit wire at the gauge then try it. If it still pegs then the gauge is bad. If not you have a short in the sending unit wire.

 

[JDA1953]

Re: Oil Pressure "PINNING"

I hooked up a NEW sending unit wire directly from the sending unit to the guage and the same "pinning" happens? The back of the guage has 3 wires and a ground. One is the light, one is guage power I guess, but I don't know what the other one might be. Any other thoughts?
Thanks
Dave

 

[Don S]

Re: Oil Pressure "PINNING"

What are we working on?

http://forums.iboats.com/showthread.php?t=220416

 

[JDA1953]

Re: Oil Pressure "PINNING"

It's a 1990 Marlin 19 ft. It has a 4.3 litre Volvo with a dual prop leg. I've gotten everything else to work except this darn guage!

 

[Don S]

Re: Oil Pressure "PINNING"

You should have 4 wires going to the gauge,
1. Black goes to ground G, -. grd, terminal or the mounting studs depending on gauge.
2. Purple goes to the I terminal of the gauge.
3. Dark blue goes to the light.
4. Light blue goes to the S terminal (Sender) on the gauge.

 

[JDA1953]

Re: Oil Pressure "PINNING"

Hey, thanks.
Yes, there are 4 wires. The ground is fairly obvious. It is in the center and has multiple connections. The blue one does go to the sending unit. I changed the sending unit, since that was an easy first try to fix this. Yesterday, I disconnected the sending unit wire and just ran a new one from the guage to the engine. The results were the same. The needle just clicks over to the extreme high end of the guage. So, it would appear that there is an issue with either one of the other wires, or the guage is shorting itself out!
I don't know what the "I" wire is that you mentioned. I presume it's the "power" for the actual guage function?
Dave

 

[Don S]

Re: Oil Pressure "PINNING"

Yes, the I stands for Ignition (purple) and is the power for the gauge.

 

[JDA1953]

Re: Oil Pressure "PINNING"

So, my next "try" is to disconnect the light wire, and see what happens, and then if that doesn't change anything then I'll disconnect the "I" wire and power the guage from another source. If that doesn't work then it would appear that the guage has decided to die! Would you agree with that?
Any other suggestions?
Dave

 

[Bondo]

Re: Oil Pressure "PINNING"

then it would appear that the guage has decided to die! Would you agree with that?

Ayuh,....

You've changed the Sender,+ the Wire,.....

I'm Bettin' on the Gauge being Junk........