Gauges Misbehaving

[Maestro]

So, my oil pressure and water temp gauges have always pegged all the way to the top as soon as you turn the key.

Volt gauge stays all the way at zero and never does anything.

Decided to start with troubleshooting the water temp gauge. When you disconnect the sender, the gauge falls all the way to zero. Tried a new sender and results were exactly as before. Figuring there was some kind of wiring mishap, I disconnected all connections to the gauge and hooked up the gauge/sender to their own little circuit separate from all other wiring in the helm. STILL SAME RESULT.

Tested voltage through the gauges with a multimeter and all have about 6-8 volts going through them. Should it be 12?

Can anyone point me in the right direction? Is the new sender potentially a dud?

[barkleydave]

gauges should not move with just power and engine off

check your ground

[Rockit]

While we're talking about gauges. Does anyone else have some of their gauges fog while underway? (They are still readable though.) Is there a cure for this or do I replace the gauges?

Thank you.

Joe

[Fastjeff]

Had low voltage problems on mine as well, caused by a bad connection at those small black fuse holders in the helm panel> I cleaned, lubed (with electrolytic grease) and crimped the connections on the back nice and tight. Picked up a few volts at the motor and many problems went away.

Jeff

[bill]

Joe,
On both my F/B Marinettes the gauges would fog over in the morning and dry out after the sun would warm them back up.
This moisture problem never seemed to effect the working parts of the gauge,
I have tried covering the gauges with a aluminum box and then covering the upper helm with a snap down Sunbrella cover. but the problem has not gone away completely. Heck on really humid days the lower inside gauges fog up.
Maybe a large dehumidifier would work.
bill

[Maestro]

Update to gauge situation: since the volt gauge was not doing anything and the others were pegging out, I decided to investigate it further and found that the positive/negative wires to the volt gauge were flip-flopped. Also, the ground for the tach was connected to the metal housing of the volt gauge.

I corrected the +/- wires to the volt gauge and moved the ground wire for the tach so that it was linked up to the common ground wire from the ignition switch.

Now when I turn on the engine all gauges appear to read properly. Temp climbs slowly to just below 160, volts at 14, oil pressure just above 40 psi.

[Fastjeff]

Lord protect us from the work done by others!

Jeff

[Rockit]

Thanks Bill. My gauges are the same way--they work fine and occasionally fog. I guess we should expect humidity on boats. . .

[jralbert]

Here's a foggy guess: when the power is on, there's some minor heat in the gauge from I know not what (electrical resistance?). That meets moist, cooler residual air and creates a mist until the heat dissipates it. That's my story and I'm sticking to it!

[Tranquilo]

Glad it was an easy fix!

Do we have a diagram for how these gages work? Testing procedures? Mods - do we have a documentation area for uploads to this server?

I'm replacing a temp sensor that I suspect is dead (get nothing) but think there may be more than one sensor I should be looking at. It stopped working after a blowing my impeller and overheating. The only sensor I know of is on the front - top of the manifold. I suspect I'm wrong.

If anyone has any docs, pdfs or pictures of this system or any other, I'd be happy to help organize them for "permanent" hosting in an online info library attached to this forum. Maybe even a youtube channel for tips & other common stuff that needs to be done on this platform. - Just a thought