How to test oil pressure sending unit

[slalomdude]

My oil gauge pegs out as soon as ignition is turned on. I removed the wire from the sender and it drops to zero. I am thinking maybe a short or faulty sender. Is there a way to check the output of the sending unit with a meter?

[slalomdude]

RE: How to test oil pressure sending unit

Well no replies, so I guess I will just have to buy a new one and try it .

[Kozmo]

RE: How to test oil pressure sending unit

I am also having Oil Pressure Gauge issue as mine goes to 0 then jumps around setting off alarms This is how CC is going about resolving it with me as my boat is under warranty.

Fromm CC to my dealer:

"It would be good to know from the customer if the 'check engine' light at the top of the dash is turning on when he notices the readings jumping around. If it is not then the switch is not the problem and we also know that the sending unit, the wiring to the gateway from the sending unit, or the gateway itself are the problem. If it is turning on then there may well be a problem with the engine oil pressure.

If you send the owner a known good gateway and oil pressure sender, he can start by temporarily installing the gateway to see if the problem is corrected. If that doesn't do it he should try the sending unit. If the problem still occurs, it is almost certainly the wiring between the sending unit and the gateway to include the connectors."

[boatech]

RE: How to test oil pressure sending unit

the oil sender does not have an "OUTPUT" . its a variable ground. check with an ohm meter from the terminal on op switch to eng ground with the engine off and if there is continuity then the switch is shorted wich is why your gauge is pegged.

[slalomdude]

RE: How to test oil pressure sending unit

Ok, i Fitted a new sender and same result. As soon as I turn the ignition on, the gauge pegs. If I take the wire off the top terminal the gauge drops to zero, If I touch the wire to the engine block, the gauge pegs again. This may be a stupid question, but does the gauge peg with ignition on and then drop off when the engine is actually cranked. I am not near thr lake so I can't start the boat. I can measure 12v at the sender wire at the sender, so I dont think there is a short.
Thanks

[dwsa]

RE: How to test oil pressure sending unit

Did you buy a marine sender unit?, I know that the auto type work in reverse. The sender is a variable resistor and I think the marine sender is max resistance with max oil pressure, where as the suto sender is min resistance with max oil pressure.

[slalomdude]

Re: RE: How to test oil pressure sending unit

Did you buy a marine sender unit?, I know that the auto type work in reverse. The sender is a variable resistor and I think the marine sender is max resistance with max oil pressure, where as the suto sender is min resistance with max oil pressure.

No, I bought it from Skidim, its a PCM part.

[dwsa]

RE: Re: RE: How to test oil pressure sending unit

I assume the gauge is original. I remember now that when I tried the auto unit the gauge would go to max before starting, after starting gauge would drop and drop further with more RPM / oil pressure.

[Daryl]

RE: Re: RE: How to test oil pressure sending unit

maybe you should hook up a manual (analog) pressure guage and see what your oil pressure really is. perhaps it is actually high for some reason....

I don't know what kind of boat you are talking about but the older boats (like mine) often have electrical issues as it relates to guages.

[slalomdude]

Re: RE: Re: RE: How to test oil pressure sending unit

maybe you should hook up a manual (analog) pressure guage and see what your oil pressure really is. perhaps it is actually high for some reason....

I don't know what kind of boat you are talking about but the older boats (like mine) often have electrical issues as it relates to guages.

Its a GT40(2000). The gauge pegs even with only the ignition on. Does anyone with a Gt40 know if the gauge pegs with ignition only, and then drops as the engine starts, settling to a normal pressure at idle?
The sender has 250 ohms resistance to ground and the new one from Ski dim is similiar.

[dwsa]

RE: Re: RE: Re: RE: How to test oil pressure sending unit

I have a GT40 in 2001 SN. Gauge does not peg with ignition on. Do you have the wires swapped with the low oil pressure switch?

[dwsa]

RE: Re: RE: Re: RE: How to test oil pressure sending unit

I think low oil pressure switch is optional, mine has it. It's right next to the oil press transducer on the same fitting.

[slalomdude]

Re: RE: Re: RE: Re: RE: How to test oil pressure sending uni

I have a GT40 in 2001 SN. Gauge does not peg with ignition on. Do you have the wires swapped with the low oil pressure switch?

No they are not swapped, if I recall, the sender has a ring lug and the switch has a spade , so I dont think they can be swapped. I am now thinking the wire from gauge to sender could be piched somewhere and causind a direct ground. I am going to run a temp wire to the gauge and sender to check. Its a frustrating one !!!

[dwsa]

RE: Re: RE: Re: RE: Re: RE: How to test oil pressure sending

If you ground the wire going onto your low oil pressure switch, does your red light on dash illuminate?? If that wire on the pressure transducer is pinched and shorting somewhere else, then removing the wire off the transducer should show no effect, will remain pegged due to the short. I will be going up to my boat in the next couple of days and will get you the answers. Just got my new cap and rotor and plugs from Skidim, hope this solves my misfire/vibration.

[M3Fan]

RE: Re: RE: Re: RE: Re: RE: How to test oil pressure sending

When you say ignition on, do you mean that you've entered the security code, then pressed start, then pressed start AGAIN to actually put the boat in IGN ON mode?