Faulty Temp Gauge

[mjlafrate]

I have a 1993 Euro F3 that I just bought used.

I've been troubleshooting a temp gauge that won't work. I pulled the sending unit, grounded the sending unit to the engine, and put heat to the sending unit and the gauge starts to move up on the scale. I put the sending unit back in it's threaded hole and when running the boat the gauge won't budge. Any ideas? I was thinking that may be the sending unit is only reading very high temps. Could that be the problem?

Thanks for any help you can give.

Mike

[JeffK]

It is most likely the cannon plug that attaches the boat harness to the engine harness that is causing this problem and the fuel gauge problem. With the key on, wiggle the cannon plug and see if the gauges jump at all.

Take a look around the ecm for a round plug that probably has a hose clamp on it. Carefully unplug it, make sure all of the posts are straight and carefully plug it back in. You may have to twist the plugs SLIGHTLY in opposite directions to make sure they are making good contact.

[mjlafrate]

It is most likely the cannon plug that attaches the boat harness to the engine harness that is causing this problem and the fuel gauge problem. With the key on, wiggle the cannon plug and see if the gauges jump at all.

Take a look around the ecm for a round plug that probably has a hose clamp on it. Carefully unplug it, make sure all of the posts are straight and carefully plug it back in. You may have to twist the plugs SLIGHTLY in opposite directions to make sure they are making good contact.

I pulled the cannon plug apart and see that on the male side of the plug the resin between the posts is cracked and now the the fuel gauge is jumping all over the place no matter where I position the plug or if a slightly twist the cannon plug clockwise of counter clockwise. Does this mean I need to replace place the wiring harness and if so is it possibly the male side? THANKS!