Help with gauges

[edu01jose]

Yesterday I installed a used gauge set on my boat. All of them work except for the Water PSI and the Fuel Gauge.

Before installing this set the old set water psi used to work just fine. Now the needle starts at 30PSI and when i give it some gas it moves but moves towards 0 psi. I would like it to start from 0 and go towards 30 psi.

Is there anyway to get to the needle on the gauges? How would I clean the gauge?

The other one is the fuel gauge. It has never worked for me. The last one read fuel when the tank was half way full.
This one is stuck way past full, Is there anyway I can move the needle inside the gauge?
I don't see an opening or anything for it.

Thanks!

 

[Monterey10]

Re: Help with gauges

The adjustments are made at the sender, in the tank. Generally, there are two sizes of senders, 1) THose for deep tanks and 2) Those for shallow tanks. IF you have a middle sized tank with the shallow sender, you may need to adjust it so it shows the bottom 2/3s of the tank. Usually, the sender is a float mounted to a heavy wire, that can be bent to change the elevation of the float.

These senders do go bad. They're not too expensive to replace. Pay attention to the gasket at the top. No fuel should be leaking out of this seal when underway.

So, what you see is that gauge showing full for a few hours, then it starts moving down (through the bottom 2/3s of the tank)

I would never try to fix a gauge, not when there are 100s of them on Ebay for $8...

Many, many times, the wiring is not set up right. It is a very simple circuit. Pay attention to the ground on the sender. Pay attention to the 12 volt feed at the gauge. Sometimes, if there is corrosion or a worn ignition switch, you will find 5 volts at the gauge. You need to fix this first, then return to trouble shooting the circuit.

 

[Silvertip]

Re: Help with gauges

If the fuel gauge has never worked then you can probably eliminate the gauge itself as the problem but here is a quick check.
1) Disconnect the sender wire (usually pink) from the "S" terminal on the gauge.
2) Turn on the ignition and then momentarily jumper the "S" terminal to the ground terminal.
3) If the gauge is OK the needle should jump to FULL.
4) If it doesn't. make sure there is +12 volts and ground to the gauge.
5) if the gauge is ok reconnect the pink wire.
6) At the sender, disconnect the pink wire from the threaded terminal.
7) Measure the resistance fo the sender (threaded terminal to the metal shell of the sender). With a full tank the resistance should be about 33 ohms, with 1/2 tank about 109 ohms and empty about 240 ohms.
8) If the reading is in the range indicated them make sure the metal shell of the sender is grounded.
9) The last check is to make sure the pink wire is not shorted to ground or broken anywhere between the sender and the gauge.
10) At this point, if you did everything right the gauge should work.

It is possible the swing arm on the sender is hung up or that the float has become soaked with fuel and can no longer provide proper readinigs. Remove the sender, pull of the float and see if it floats in a container of fuel. Senders are available in many varieties including "universal" that you can set up for any depth tank. Get them right here on iBoats.

 

[edu01jose]

Re: Help with gauges

Thank you so much silvertip and monterey.

I will print this page up and when I got to the boat next week I'll check everything.

Is there any way to fix the water preassure gauge?
If I'm right, if I blow on it it should move correct? as it works with air.

 

[Silvertip]

Re: Help with gauges

The water pressure gauge works on air pressure. Neither water nor air passes "through" the gauge. Water pressure compresses air in the tube. A coiled tube in the gauge tends to unwind under pressure which causes the needle to move but if you have a good set of lungs you may get a reading.