SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: marty722 on March 13, 2009, 12:09:05 PM
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oil pressure gauage pegs out when started and stays there. Shut off eng unplug wire start motor and stays at 0. Hook wire back up and start eng and it pegs out again. Shut off eng and stays pegged..... Now pegged is at 60psi. Could it be that it's working fine? Is 60psi when cold to high? Maybe a short in the wiring? The gauage is good. Any thoughts??? Thanks for your help.
Marty
Marty722
Hotboat member
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Did you replace the sender, or has the boat always been this way?
The way the sender works is that it varies resistance to the gauge, and there are two basic types of senders,, normally open contacts, or normally closed. If you have the wire off the sender, turn on key,, no need to start engine, touch the wire to ground will probably peg the gauge.
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just got the boat so it is what it is. I touched a ground with the key on and yes it did peg out.....
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ok,, so you need to get a different sender for the gauge,, the brand of the gauge should be enough to be able to buy one.
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the last owner said that he had no probs with the oil gauage. So are you saying the sending unit is either bad or does not match the gauage? Sorry for the stupid question the electrical is not my cup of tea? thanks
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You may have an idiot light sender. They are either ON or OFF.
The gauge needs a variable sender.
I don't know how you could test the sender without a pressure you could vary.
You could ohm the sender but it would happen so fast I don't think you would have time
to tell if it were variable or not.
What brand gauge are we talking and can you see any markings on the sender? I'm guessing not.
It's reasons like this I now have a mechanical AND electric oil pressure gauge for back up.
Good luck.
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The senders are available in two different types. Try calling Rex Marine and see what they have. Any shop that has sold gauges and senders for any period of time will be aware, and should be able to sell you the correct one, especially since you know that if you ground the gauge it pegs rather than going to zero.
You could put an ohm meter on the sender, but you have already proved it to not be compatable with the gauge, or broken (stuck)
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this is a indmar eng that has the senser by the oil filter that looks big and round like a fuel filter.
So my question is what should it do with the key on and touching a ground. go to 0? or peg out?
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If the disconnected wire shows "zero" on the gauge, then touching to ground should peg the gauge. With a single wire sender, the circuit is completed to ground.
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Key on engine off the needle should read zero. If it pegs I would say you have the idiot light sender. Without oil pressure the idiot light sender will light up the bulb= pegging the gauge.
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Sounds like the guage may have had a Ground issue or as said here wrong/failed or shorted sender Most senders have a "Value" stamped into the hex area above the threads and below the potentiometer portion eg 80 or 100 , cant mix 100 psi senders with 80 psi guges (peg) Also a bad ground (dash to engine ) will cause the guage to peg and last but not least guges dont like to be pegged for a long time if it stayed pegged chances are the guge ids "done". check pwr and grd for sufficiant voltage and solid grd , then run a compleley seperate wire from the system to the sender spade or terminal (key on engine off) the guage should zero if it pegs, the sender is likely shorted Tom