1986 Chris Craft gas gauge or sender issue?

[Fiat4Fun]

Had an interesting issue come up last time on the water. When we went out for the first time, our gas gauge looked like we had under 1/8th of a tank. So, the next time we went out, I put in 30 gallons of gas ( 60 gallon tank). However the gas gauge reads full. Could this be a bad float in the sender or a bad ground wire? Any advice before I dive into the issue?

 

[Scott Danforth]

could be any of the above.

start at the gauge, read the ohms, check the connection, ohm out the wire, clean the connections at both ends of the wire, etc.

 

[Fiat4Fun]

Finally got around with checking the boat gauge. I did replace the old school sender with a new style VDO sliding sender. Same issue. The gauge stays on full. IF I unhook the pink cable at the sender, the gauge goes to empty. IF I un hook the ground cable at the sender, it goes to empty. SO I assume that means there is not short in the ground cable. I am now thinking it's the gauge. Can gauges be fixed? I would like to keep the style the same as the others.

Any other suggestions would be appreciated. Might try running a wire from the sender to gauge just to check ........ any other ideas would be great....

 

[airshot]

Might hust ve a lousy gage and sender. The way boats operate, gas gages can read off. My own does similiar things. It stays full, until the tank us almost half empty then suddenly shows 1/2- 3/4 full. When up on plane it reads different than going slow due to angle of the hull. Over time I have learned to read the gage at idle speed, anything else is a guess, also I have vecome familiar with how far I can go on a half tank or so, so I have a reserve half to fall back on. I rarely let it get below half before looking for a refuel. Not sure you have an issue other than a typical not very accurate boat fuel gage !!

 

[Fiat4Fun]

Well, I pulled the fuel gauge, and used the old sender on my work bench and it wall worked perfect. SO, it has to do with the wiring in the boat.
Will start going through that. But at least I don't need to get a new gauge and try to match it with the other ones ;-)

 

[Scott Danforth]

Did you read the ohms prior to yanking

 

[Fiat4Fun]

I did read the old sender before taking it out, and was getting "flaky" readings and it was a last replaced 15 years ago. It was the old cheesy arm type, so since I already pulled it out I replaced it with the newer style VDO version. The gauge connections were hard to get to unless I removed the gauge. Now I am going to have to check out the wring.
I think the issue is with the ground, but I don't understand why the gauge was reading full...........

 

[Fiat4Fun]

Finally got it figured out.
The VDO gauge has a small nut on the ground post that holds the spade on. The nut had come loose, which made the ground flaky. Once I went in a tighten it all was good. The wiring was intact and I check for shorts. When the ground on the gauge was "loose", it would peg the gage to full. Problem solved