Pressure Guage ?

[MudPumper]

I have older style Hardin Marine Guages. When I turn the key to on, the Oil pressure guage pegs all the way over. When I removed the wire from the sender in the block the needle goes back to 0. Does this mean the sender is bad or could it be something else??

[moneysucker]

The sender is grounded out the guage will do the same if you ground the wire to the block. Replacing the sender should solve the problem. 80 psi should make you feel good seeing it all day though.

[BigBlockBaja]

Mud,
I just went outside to look at mine and when the key is on, not running, it pegs out to 80 psi. With the wire grounded to the block, Its also 80 psi. But with the boat running its right at 40 psi. Brand new sender.

[MudPumper]

Bitchen, I pulled the wire and it did the same shit. The only problem is that it also pegs with the motor running. I have a new sender coming so i'll see if thats it. I just thought it might be in the wiring somewhrere.

[BigBlockBaja]

Im interested to see what you get with the new sender. Reason being, I've been running mine on the trailer, jet disconected, and revving the hell out of it and the pressure stays right at 40 psi.. no change with rpm increase.

[Wet Dream]

I had something similar with my boat. I picked up a new sender that was supposed to be the unit for an Olds motor, in a car, This one was long and skinny, not like the one on the boat which looked like a bell. When I hooked up the wires, it pegged the needle to max. Hooked up the bell and it was fine. Seems to be a different grounding or resistance setup.

[Squirtcha?]

Zactly. I've seen a book with pages of oil pressure sending units for a BBF. Mine was bad so I was trying to match it with the old one. Tried several that were supposed to be close and never hit on the right one. Eventually I ended up buying a new gage which came with it's own sender. Works just fine now.
Also picked up a new water temp gage (didn't come with a sender so I used the old one) and found that it reads about 20 degrees higher than my old gage did with the same sender. Not sure which one was right now.

[MudPumper]

It's a bitch trying to match senders to guages. Especially when my guages are 20+ yrs old. I wouldn't mind a new set of guages with matching sender but I don't really have the cash at the moment. Besided I really like the look of my old guages.
Don't mind the GPS in the pic, it's the only one I had showing the guages.
http://www.***boat.com/image_center/data/520/1653FC_GPS-med.JPG

[King Kuracz]

Originally posted by MudPumper
Bitchen, I pulled the wire and it did the same shit. The only problem is that it also pegs with the motor running. I have a new sender coming so i'll see if thats it. I just thought it might be in the wiring somewhrere.
If the gauge pegs with the wire disconnected at the sender and the ignition on you have a short to ground in the wire from the "s" terminal on the gauge to ground. Try disconnecting the wire from the "s' terminal on the back of the gauge. If it still pegs, bad gauge, if not short to ground in the wiring somewhere.
If the gauge is pegged even with the power off sounds like a bad gauge.

[MudPumper]

No, the guage goes to 0 when I pull the wire from the sender. And when the key is off the guage is off.

[King Kuracz]

Bad sender, shorted internally to ground.