Adding Inductive Hour Meter To Boat

OK folks, this is my first post and after some browsing thought that this sub forum was most appropriate due to the chatter about ignition coils and tach signals.

I bought a very inexpensive hour meter with the hope of running it on my boat engine which uses ignition coils! This hour meter is meant to wrap around a spark wire and will automatically count engine hours when there is sparking present (ie it also has a little tachometer which I don't really care about).

So, since I don't have spark wires what to do? Well it turns out this inductive hour meter will sense and turn on when connected to any AC voltage- it sees the 3600 Hz pulse and add up run time hours. I was hoping I could just connect it to ignition on DC but of course there is no pulse and it doesn't work.

What can I connect this to on my boat that will give it a pulse when the engine is running? Can I Tap-splice it into an ignition coil wire, or a tach signal wire? Are those signals pulse?

I wonder if I can sense an inductive current from those pulsed wires? Any thoughts?

Thanks

I would start by trying to hook it to a fuel injector.  If that doesn't work try a coil drive wire.

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Kevin Pierson

Is it generally safe to tap a fuel injector signal wire or would adding a very small drain device cause other problems?

As long as what you are adding is high impedence (low current) you shouldn't have any issues.  A fuel injector is a solenoid and the coil of the solenoid is very similar to that of a relay.  An extremely small load in addition to the fuel injector won't affect anything.

The most important thing is to make sure you make a good connection - you don't want the splice to fail and possibly break the signal going to the fuel injector (ie don't use crimp connectors, ttaps, or scotch locks).

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Kevin Pierson

Thanks, so basically that rules everything out but directly soldering to the wire.

Thanks for the advice. I will update you how it turns out.

:)

In my humble opinion, ALL splices should be soldered, but anything that is engine critical or exposed to moisture it is imperative that they are soldered and insulated properly.

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Kevin Pierson

Is it OK to do a scotch lock splice to see if it works, then, make it permanent?

Does a scotch lock (if correct size used) cut the wire? I'd guess not, that if it didn't work I could just take it off and tape it up nice and tight where the insulation was pinched.

A scotchlock, by design, won't cut the wire.  However, if you use the wrong sized connector on the wrong size wire it can cut in to the wire.

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Kevin Pierson

the other down side to them is they fall off easily. especially in a situation like a boat. and they allow corrosion into the wire, especially in a situation like a boat. but for a temporary test, it shouldnt hurt as long as the wire doesnt get cut by it.