CONTINUOUSWAVE

Can you use an analog gauge with the Mercury 150 FOURSTROKE engine?

That is, can I put in a temperature gauge and use the existing sending unit wire of the Mercury engine?

And the same for Oil pressure?

If an engine already has a temperature sensor installed on the engine power head, I would presume the sensor must already be connected to some sort of instrumentation. If my assumption is correct, then connecting a second instrumentation in parallel with the first instrumentation to that sensor would most likely not work. Typically all electrical sensors react by altering the flow of current through their electrical circuit; the current is supplied by the instrumentation. Connecting two instrumentation devices to one sensor would affect the current flow and probably produce an error in the sensor reading.

If an engine has provisions for attaching a sensor, and presently no sensor is attached, you can easily install a sensor and connect that sensor to any sort of instrumentation you like.

Also, in my opinion, it would be very odd to find an engine that has a sensor installed already but has provided no instrumentation to use the sensor.

If an engine provides for a location for a sensor, and the engine wiring harness provides a conductor for carrying that sensor signal to instrumentation at the helm location, you can certainly install a sensor and use the provided wiring to carry its signal to some instrumentation at the helm.

For advice that is specific to a particular engine brand and model, I recommend you contact a reliable and informed dealer that sells that brand and model for his advice.

And the sensor and the gauge have to match each other for an electrical gauge, they measure via a range of resistance at each end. At least that's the way the older non mechanical gauges work.

After a little more investigation my understanding is the outboard sending units are digital and the gauge I want to use is analog. Is that going to be an problem?

Thunderjet wrote:...the outboard sending units are digital and the gauge...is analog. Is that going to be a problem?

Yes.

If you want to use traditional analogue gauges and sensors, you will have to install the proper sensors on the engine and connect them to their corresponding gauges. You can easily install a temperature gauge on the engine, although you may have to invent your own mounting location and a means to hold it on the engine block. For the oil pressure gauge you will have to find an appropriate place in the oil system flow to install your new sensor.

It will be quite a bit of work to figure out all this. Why don't you just buy the Mercury gauges that use the Mercury sensors in your Mercury engine?