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Author Topic:   Conventional Outboard Motor Gauges
mrtoyz posted 06-23-2010 01:31 AM ET (US)   Profile for mrtoyz   Send Email to mrtoyz  
I need help picking gauges. I've looked at Faria and Teleflex but I'm unsure what I need to be looking for [to be compatible with a] Mercury two-cycle outboard. Here is what I'd like:

--white gauges;

--[speedometer]--I can't find any [speedometer] that goes down to 5-MPH and above 35-MPH. I have to have at least 40-MPH

--tachometer with hour meter if possible;

--voltmeter--not sure of voltage requirements. I would really like a digital gauge but I can't find one.

--tilt--current gauge is broken. I'm assuming they'll work with my engine;

--Water Pressure--I'd like to make sure the impeller is working; and

--Fuel gauge.

What is Faria battery condition indicator?

Am I missing anything? Thoughts? Many thanks.--T

jimh posted 06-23-2010 07:34 AM ET (US)     Profile for jimh  Send Email to jimh     
Speedometers usually work from a Pitot tube pick-up. Some Mercury engines have a Pitot tube pick-up built into the leading edge of the gear case. If you want to use that Pitot tube for the speedometer you will have to get a a speedometer that is calibrated for it. Otherwise most speedometers are designed to work with their own Pitot tube pick-up. Pitot tube operated speedometers are not generally used for slow speeds. For accurate slow speed measurement a paddlewheel sensor is typically used. These tend to lose accuracy at higher speeds.

Pitot tube and paddlewheel speedometers measure speed through the water. This is typically important for fishermen who want to troll at a precise speed or water skiers who want a certain speed through the water.

Most people monitor their boat speed using a GPS receiver. A GPS receiver gives fairly accurate measurement of speed over ground. If the boat is traveling in water with current, the speed over ground will be different from speed through the water.

jimh posted 06-23-2010 07:38 AM ET (US)     Profile for jimh  Send Email to jimh     
Most voltmeters for use on a 12-volt DC boat electrical system measure in the range from 0 to 16-volts.

To learn about a Faria battery condition indicator I recommend reading the Faria literature.

jimh posted 06-23-2010 07:39 AM ET (US)     Profile for jimh  Send Email to jimh     
A tilt position indicator gauge must be matched to the brand of motor. The arrangement of the tilt sensor varies with different brands of outboard, and therefore the meter must be matched to the motor.
jimh posted 06-23-2010 07:42 AM ET (US)     Profile for jimh  Send Email to jimh     
Water pressure gauges typically operate from a hose that is connected into the engine cooling system. There is some variation among engine brands in the type of hose and connection used. Mercury typically uses a very small diameter semi-rigid hose to connect their water pressure gauge.

The usual range of pressure varies with the engine brand and power. Ranges of 0 to 15-PSI and 0 to 30-PSI are typical choices.

jimh posted 06-23-2010 07:46 AM ET (US)     Profile for jimh  Send Email to jimh     
If you want a fuel tank level gauge there are two general types:

--mechanically linked
--electrically linked

Mechanically linked fuel tank level indicators usually sit atop the fuel tank. They cannot be located on the instrument panel on a dashboard.

Electrically linked fuel tank level gauges use a fairly common standard for the tank level sender. If your boat fuel tank has an electrical tank level sender, it likely will be the standard variable resistance type sender. The topic of fuel tank level sender options is extremely broad. If you need more advice on electrical fuel tank level senders, see

mrtoyz posted 06-23-2010 04:43 PM ET (US)     Profile for mrtoyz  Send Email to mrtoyz     
I just talked to Moeller and they told me that putting a sending unit on their topside tanks is NOT recommended at all so I guess that is out.

[Changed topic to on-deck fuel tanks. Please use THE GAM or REPAIRS/MODS to discuss fuel tanks. SMALL BOAT ELECTRICAL does not discuss on-deck fuel tanks.--jimh]

davej14 posted 06-23-2010 07:47 PM ET (US)     Profile for davej14  Send Email to davej14     
Rather than a fuel gauge, consider adding a fuel flow sensor to your list. I have a Lowrance gps/sonar that displays the data from their EP-10 sensor. Beside an accurate reading of fuel remaining it will calculate rate of consumption and distance to empty. I really don't look at the oem fuel gauge other than as a backup.

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