Problem with new gauges

[andrewterri]

Yet another issue :facepalm:​. I just installed new Faria gauges on a 89 searay 3.0. The alternator, oil pressure, and temp are not correct while the fuel and tilt and trim seem correct. I understand that I will need to buy new sending units that match the gauges, correct? But why is the tach not working correctly? It shows the engine is turning at 400 RMP but the multimeter is showing 950 which the engine matches in sound. The gauge is set on 4 cylinder on the back and if my understanding is correct the tach gets the signal from the coil so there is no adjustment to be made. Any suggestions on how to correct these problems and make the gauges acurate?

 

[alldodge]

tach not working correctly? It shows the engine is turning at 400 RPM but the multimeter is showing 950

Being new gauges, and if your sure your multimeter and ear are correct, then you need to contact the place you bought the gauges and ask for a replacement. The tach gets its signal from the negative terminal on the coil, the gray wire

 

[achris]

Yet another issue :facepalm:. I just installed new Faria gauges on a 89 searay 3.0. The alternator, oil pressure, and temp are not correct while the fuel and tilt and trim seem correct....

Sounds like a ground issue, especially with the voltmeter involved.

 

[andrewterri]

The idle seems right on so I think I might have to disassemble everything and return. What about the alternator? Where does that signal come from? It shows roughly 10.5 with the new gauge. When I took the old one off it was right on.

 

[andrewterri]

A bad ground somewhere would make sense. The wires have been redone several times by PO's. Could I just run one ground wire from the battery then piggy back to each gauge?

 

[achris]

A bad ground somewhere would make sense. The wires have been redone several times by PO's. Could I just run one ground wire from the battery then piggy back to each gauge?

That would work.

 

[andrewterri]

just went and filled the boat up for the 4th and the gauge was only showing 3/4 full. Is the only option on that is pulling the tank and removing the sending unit to find one that matches the gauges ohms? I am assuming I have a good ground on that gauge since it is working. A bad ground could not make the gauge work only part way could it?

 

[achris]

Gauges come in a few different ranges, the most common, and probably what you have is 33 to 240 ohms. The senders are the same. What does need to be done with fuel tank senders is they need to be set up for each particular tank. With the sender will be an instruction sheet showing how to set up the float to give the right readings. Just measure the tank depth and set the sender up according to the directions (all senders have different set ups)...

Chris........