Instrumentation FAQ’s

How do I adjust the selector switch on my tachometer?

See the Tachometer application guide in technical support. On the rear of the tachometer the black rotary selector switch is placed in the 4C, 6C, or 8C position respective of how many cylinders there are in your Stern Drive or Inboard engine.
Place the selector switch in positions 2P, 3P, 4P, 5P, or 6P for Outboard engines listed in the Technical Support, Tachometer Selection, (Outboard Engine with Alternator.)
Universal Tachometers with this type of labeling of the selector switch are capable of operating on both stern drive/inboards (4 cycle) and outboard engines.
Certain Chrysler and most pre 1993 Force outboards require a special tachometer that will operate correctly for the 20 pole alternator on those engines.

What engine temperature gauge do I use on my outboard?

SeaStar Solutions has replaced all of its 50-200 degree O/B temperature kits with a more generic kit that can be used on all outboards having a 12-volt battery. These new kits cover a temperature range of 80-220 degrees. The gauge reads C to H with graduated marks in between for reference. The kit comes complete with gauge, proper sender, brackets, and instruction sheet that adapt it to almost any outboard engine.
For replacement parts, sender IA96035 must be used with a 50-200 degree gauge. Sender 52320S010 must be used with a C-H gauge. If an IA96035 sender is used with a C-H gauge, the gauge will read at the 200-degree area very quickly.
The 120-240 degree stern drive temperature gauge can be used but it will register temperatures in the low temperature area (on most engines) when engine operates normally. Sender 52320S010 must be used. If sender requires a bracket for installation, use bracket IA55009.

My engine synchronizer gauge pointer is pegged to one side of gauge?

First, check all the connections to make sure they are clean and tight. Of the two main components of the synchronizer, the module (black 5″ disc) usually fails before the dash mounted gauge. It has all the electronics and is more susceptible to electronic abnormalities. If the dash gauge pegs to one side the fault is almost always the module. The module part number is located on the under side of the module.

Why does the Trim Gauge not work on my engine?

Trim gauges are made for specific trim sender resistances. The senders are only made and sold by the engine manufacturer dealers. In many cases the sender has failed but the gauge is the first place the fault is seen. The sender can be checked for the proper resistance if incorrect responses are seen on the gauge. The trim gauge must also be matched to the sender for a correct response.
Force (’95 and on), Mariner, Mercury, Mercruiser, OMC Cobra (gray):
10 ohm Down, 167 ohm Up
OMC Stern Drives (white) and Sea Drive:
10 ohm Down, 88 ohm Up
Johnson/Evinrude Outboard:
88 ohm Down 1 ohm Up
Removed OMC & Sea Drive
Suzuki 4-stroke Outboards (2002)
88 ohm Down 2.5 ohm Up
Yamaha Outboard:
Pre 2001 – 110 ohm Down, 410 ohm Up
2001 (“z” in engine number) – 10 ohm Down, 167 ohm Up
OMC/Volvo combination stern drive, DP, SX:
10 ohm Down 167 ohm Up
NOTE: Honda Outboards & Suzuki 2-stroke Outboards do not use a resistive type sender.
SeaStar Solutions does not offer trim gauges for Force, (pre-’95), Pre 1992 Suzuki, Nissan or Tohatsu engines.
The trim gauge can be tested in the same manner as the fuel gauge. Turn the ignition on. Remove the sender wire from back of gauge. Pointer must go above UP (below DOWN for 88-1 ohm gauge). Next, connect the gauge sender terminal to ground. The pointer must go below DOWN (above UP for 88-1 ohm gauge). If the pointer moves to both UP and DOWN the gauge is functional.

What water pressure gauge is correct for my engine?

Water pressure is monitored because proper pressure means adequate water flow resulting in acceptable operating temperatures. The correct pressure varies with each engine and the engine manufacturer should be contacted when there is a question. Most engines can be covered by a 0-30 PSI range (a few newer outboard engines require a 0.48 PSI kit). Yamaha engines require a 0-40 PSI kit as well as bushing adaptor 61886P.
The pressure gauge adapts to the engine in various ways. SeaStar Solutions provides a kit that includes the gauge and all necessary fittings to adapt to most U.S. built engines and some imported engines. Access to water pressure may be at the overboard discharge hose, a water by-pass hose, or a fitting directly into the cylinder head cover (some offshore engines require a metric threaded fitting that SeaStar Solutions does not supply and therefore does not recommend the kit in these applications. SeaStar Solutions does have available bushing 61886P for Yamaha). The kit may have more fittings than are necessary for a particular application. However, the extra parts may come in handy for some other job.
Water pressure kits are not tested for coolant systems on inboard or stern drive engines.
The application chart for water pressure kits can be found in Tech Support, Outboard Water Pressure Kit Section.

Do I need a voltmeter or an ammeter?

In years gone by most inboards and stern drives were equipped with an ammeter, usually of 40-ampere range. Today almost all manufacturers have redesigned for voltmeters. There are a number of reasons for this change. Voltmeters tell more about the electrical system than ammeters. Ammeters tell if the alternator is or is not charging the battery enough to overcome the boat’s drain on the battery. If properly wired it may also tell if the battery is being drained with the motor off. However, this drain can be so low that the ammeter will not register or alert the operator to the drain.
A voltmeter can provide the operator more information. Condition of the battery at idle or with the engine off, is the battery being charged when the engine is running above idle, is the voltage regulator set correctly.
Additionally, the voltmeter is easy to wire. Install in dash, connect I to ignition switch or any good-switched positive wire from the battery, and connect G to common ground. The voltmeter is in operation giving information on the electrical system. Wire size can be 14 to 18 gage. An ammeter requires 10 gage or heavier wire to be brought to the dash from specific locations on the battery or engine.
A voltmeter cannot use the wires an ammeter used. If substituting a voltmeter, contact SeaStar Solutions concerning wiring changes.

I measured the temperature sender hole in the water jacket and when I got that size sender it was way too big.

National Pipe Thread (NPT) sizes used on temperature and pressure senders are not the same as measuring the hole or sender with a tape or ruler. NPT threads are tapered so they tighten and seal as they are threaded into the hole. The way NPT threads are measured comes from the plumbing industry. For example, a steel pipe, hollow on the inside, has a 1/2″ inside diameter. It has a wall thickness around that diameter. A tapered thread is cut on the outside of the pipe wall at the end of the pipe. This thread is called a 1/2″ -14 NPT because the inside of a theoretical pipe is 1/2″ inch in diameter and there are 14 threads to an inch of length. Even though senders have no inside diameter their threads are measured the same way. If unsure about the size of the thread, inexpensive pipe plugs from the hardware store can be tried for fit. Refer to Tech Support, Sender Thread Sizes.

Why does the Older Force outboard engine require a special tachometer?

Almost all outboard engines that have an alternator can be monitored by our Universal Outboard Tachometer. That is because most outboard alternators have magnetic pole ranges from 4 to 12 poles. The tachometer is adjustable to those ranges. However, some late model Chrysler outboards and most pre 1993 Force outboards have Prestolite 20 pole alternators. The Universal tachometer is not adjustable for that number of magnetic poles. To expand the existing Universal tachometer from 4 to 20 pole would jeopardize the electronic noise filtering. Therefore, a tachometer that handles only the 20-pole alternator was created. The SeaStar Solutions catalog and brochures specify this tachometer, P/N 53743P. Most Force engines built after 1992 have more standard 12 pole alternators and can be monitored by the Universal Outboard Tachometer. If in doubt on the number of poles in a Force alternator consult our tachometer application guide, a Force dealer, or Mercury (the Force parent) customer service ( 920-929-5040 ).

I can’t locate the gauge anywhere that I need to replace.

SeaStar Solutions manufacturers many lines of instruments and is constantly introducing new designs to meet the OEM’s requirements. To make room for the new, some of the old must be discontinued. In most cases SeaStar Solutions does offer a replacement gauge to monitor the function, although styling may be different. If you know the part number of the old gauge, call us for availability.

I am having difficulty with my fuel gauge.

The SeaStar Solutions fuel gauge and the level sender are designed to operate on 240 ohms (empty) and 33 ohms (full). Most other manufacturers build a marine fuel level system of the same resistance as gauges and senders may be mixed at the boat builder level.
There are only three components to the system-gauge, level sender, and the connecting sender wire. The sender wire should be inspected for breaks in the copper or corroded connection to the terminals.
The fuel gauge can be inspected in the following manner. Turn the ignition on. Remove the sender wire from back of gauge. Pointer must go below the empty mark. Next, connect the gauge sender terminal to ground. The pointer must go above the full mark. If the pointer moves past both E and F, the gauge is functional.
To check the fuel level sender remove wires from sender terminal. Connect volt/ohmmeter to two sender terminals (digital ohmmeter will tend to be jumpy). Ohmmeter should read approximately:
240 ohms @ empty
100 ohms @ 1/2 and
33 ohms @ full.
If the sender is not sized properly for the tank, errors in gauge reading can also occur.

Bouncing, Erratic Tachometers.

As analog tachometers age they sometimes begin to behave unpredictably and do not always display the correct RPM. Sometimes tapping on the glass brings the tachometer back to the correct reading…temporarily.
This abnormality may be caused by a thin film that grows between the Selector Switch contact and the circuit on the printed board. This film tends to intermittently insulate the two causing the strange readings.
To remedy this, simply rotate the switch about 6 times, resetting the switch to its original position. This should eliminate the film build up and all return to normal.
Erratic operation can also be the result of old age or a power surge (lightning for example) acting on the internal electronic components. This you can not remedy and the tachometer must be replaced.