The last 2 nights I've been getting back to the dock after sunset. I noticed 2 things and I'm not sure if they are related or not.

1) While idling or slightly above idle the nav lights, primarily the 180 light, will pulse as if on a dimmer switch at about 1Hz. When running around 2900rpm the nav lights are fine but the digital synchronizer light pulses ever so slightly. While idling in the channel I can goose the port throttle and force the lights to flicker and back to idle and all is fine. Didn't try it but I don't think the starboard throttle is having this effect.

2) While in route around 2900rpm the port tach on bridge begins to flop around +/- 10rpm but I CAN'T hear/feel any engine change and the tach at the lower helm appears to be normal. It only seems to do this while at cruising speed only.

I'm going to clean/check all connections on back of the tach and pull the alternator to have it tested at the local marine repair place.
I was going to breakout my meter but I didn't feel like fooling around in the engine room on the lake at night.

I'm not sure if these 2 issues are related or not since they appear to occur independently of each other.

I have the 2 wire alternators and just replaced the voltage regulaters on both engines. The port alternator is an obvious replacement as it has no Chrysler paint. It is a Prestolite.

Any ideas?

-Karl

Your nav lites etc are leaking to ground. Begin by cleaning everything on the boards on the FB. Gunk, moisture etc collects on the circuitry and in this case it is bleeding when the Nave lites are fired up. It also can be and highly likely there is isolation leak on one or more of your nav lite sockets causing a slight drain to ground and dimming the lights. Dirty ground connections can also cause the same system.

Suggest you start by isolating your nav. light curcuits. Disconned one at a time including ground and check for symptoms. When you find it it will be a simple fix. Best of luck.

Safe Boating,

dave

Alternator tested at 50A in both directions, not that direction should matter.
Suggested checking the connection to the voltage regulator which I had recently replaced.

-Karl

Why not switch to the 1-wire jobs from Fulton Armature? Think I paid ~ $120 each, for 100a Delco's. Just changed the wires to #4 AWG.

I am familiar with this. The other day I discoverd that the voltage at the 25A circuit breaker on the engine was .5v higher than the voltage at the ship's power buss (after the shunt on the ammeter) UNDER LOAD. The readings were the same with no load. The resistance of the #10 gauge wire feeding the ammeter + the resistance of the shunt was dropping .5volts!

This is how I troubleshot it:
checked the 25A circuit breaker (CB) (.01 OHMS, OK)
checked the connections at the CB (cleaned them up, OK)
checked the voltage at the CB - 12.8V (both sides under load)
checked the voltage on the #10 red wire that goes from the CB, thru an engine harness plug, under the oil filter, thru another engine harness plug, and up thru the shunt to the AMMETER post - 12.3V (.5V drop).
Cut off the old ring terminals and crimped on new ones. No change. Ran a new #10 AWG wire from CB to AMMETER post. Bingo. This got rid of .3V of drop. Put wire labels on new #10 and a 'not used' on the old #10.

Also checked and cleaned both batterie's connections and the GROUNDs: one from the batteries to the hull ground point, from hull to engine block, and from engine block to SHIPS GROUND BUSS at helm. Checked the BATTERY SWITCH's connectons too.

Still have a .2v drop across the ammeter shunt. Ordered a new digital ammeter and shunt. I will post the results of the new install.

DD


Picture shows 25A circuit breaker removed.

Bad luck that sucks

Mike

Ever mess with outboards? Most of the older ones only have a rectifier--that's all--to convert AC voltage to DC. No regulator at all! Put a meter on the battery and you wouldn't believe what you see: voltage spikes all over the place!

I suspect that's what's happening here, a bad rectifier in the alternator.

Jeff

dennis, it was the ign it feeds from the ammeter almost beside it.i'm sorry to.my wallet is taking a hit this year.


tim

Karl,
I think you can save yourself some time by having the alternater checked. If lights are pulsing 2 of the three rectifiers in the alternater must be out.

Roger

dennis ,how is your ammeter wired.has your new engine harness got an orange return wire .i think mine always reads load because the alt feeds into the red now not the orange.

tim