Mercury 150XRi Temp system question

[ufm82]

The sender in the starboard head is a single tan/blue wire that runs to the warning horn. The sender in the port head is a three wire sended with two tan/blk and a solid tan wire. I am installing a water temo gauge in my boat and tapped the solid tan wire from the port sender for my gauge but am reading a steady 225 at idle. Operating range is obiously way below that. Water from pee stream is hot but not scalding and water from prop hub is warm but not hot. Does anyone know what range the sender reads in? Voltage? Ohms? I found that it started around 190 ohms when cold and slowly went down as the engine warmed, thus my choice of gauge connection. However, I am wondering about the sensor.

Any ideas?

UFM82

 

[walleyehed]

Re: Mercury 150XRi Temp system question

Pretty sure the temp sender is just a thermo couple...which would be millivolts with a compensator somewhere in the system. The compensator would be the signal to the horn at high millivolts.
What yr.??? (S/N) I'll check my wiring diagrams...

 

[ufm82]

Re: Mercury 150XRi Temp system question

serial# OD285982
Model #1150413PD

Thanks for your help walleyhed

UFM82

 

[Dukedog]

Re: Mercury 150XRi Temp system question

Sounds like tha guage is faulty or incompatible with that sensor. If that sensor is faulty it would show up in tha way tha motor runs...............

 

[sschefer]

Re: Mercury 150XRi Temp system question

Sounds like tha guage is faulty or incompatible with that sensor. If that sensor is faulty it would show up in tha way tha motor runs...............

Sounds to me like you are using either an automotive temp gauge or a gauge designed for a Mercruiser inboard engine.

The device on the stbd head is the temp switch. It's either off or on at 190 degrees. The device on the port head is the temp sender and changes resistance with temperature (a thermal resistor). These are calibrated to work with temp gauges for Mercury outboard motors. Either original equipment or aftermarket gauges that are designed for Mercury outboards work well with the stock Merc senders.

 

[Faztbullet]

Re: Mercury 150XRi Temp system question

Sounds like tha guage is faulty or incompatible with that sensor. If that sensor is faulty it would show up in tha way tha motor runs...............

You are correct Ddog as the port sensor is the temp switch(overheat) and the starboard is a combo thermister, as the tan/blks are wired in to the TPS. If this was faulty engine would stumble/bogg and it sounds like a faulty/inaccurate guage.

 

[walleyehed]

Re: Mercury 150XRi Temp system question

Fazt, you still own the Hydra-sport????

 

[Faztbullet]

Re: Mercury 150XRi Temp system question

Yep!!!

 

[Diamond Dave]

Re: Mercury 150XRi Temp system question

I?m confused; I?m probably just not reading this correctly. I also have a 150 XRi. 1995 0G258207 The left head / port side head has a switch with 3 wires coming off it. 2 tan wires with a blk tracer, and one solid tan wire. That solid tan wire is the input for the temp gauge right? And the right side head / starboard head sensor with the tan wire with the blue tracer is for the overheat buzzer. Is that correct? Or is it the other way around?

Thanks,

Dave

 

[Dukedog]

Re: Mercury 150XRi Temp system question

You got it right. Port three wire. Starboard one wire..............

 

[Diamond Dave]

Re: Mercury 150XRi Temp system question

You got it right. Port three wire. Starboard one wire..............

Thanks Dukedog