erratic fuel gauge

[KCMILLS]

never noticed it before but now my fuel gauge is bouncing back and forth Im worried that some sort of electric problem is going on I know its grounded at the tank and the pos wire is tight, Im also having a a slight problem with the motor(idling) so i dont know if the two are related for example if a stator or powerpack is about to go does it fire backwards causing juice to go through the system,,,(hypothetical question)

 

[Mod2]

Re: erratic fuel gauge

Moving to Electric, Electronics forum.

 

[Silvertip]

Re: erratic fuel gauge

The fuel tank in many boats is long and shallow. When the fuel level begins to drop the fuel sloshes back and forth so the float rises and falls which causes the fuel gauge to respond accordingly. Nothing much you can do. Its the "Empty" reading you are interested in anyway.

 

[Silvertip]

Re: erratic fuel gauge

The fuel tank in many boats is long and shallow. When the fuel level begins to drop the fuel sloshes back and forth so the float rises and falls which causes the fuel gauge to respond accordingly. Nothing much you can do. Its the "Empty" reading you are interested in anyway. The idle problem and gauge problem are probably NOT related and no, juice does not go through the system backwards unless you reverse polarity on the battery.

 

[KCMILLS]

Re: erratic fuel gauge

im talking baout the boat on the trailer no movement when i turn th ekey to on it goes a little crazy

 

[Texasmark]

Re: erratic fuel gauge

The fuel sending unit is probably worn out. The sloshing mentioned causes the center contact, or the wires upon which it rubs to wear through. Once this happens they can break. You must be sitting right on a break and any movement at all causes the center pin to touch one side or the other of the break giving you these readings.<br /><br />The gauge could be bad from moisture intrusion or something, but usually it's the sending unit.<br /><br />Sending unit resistance varies from around 30+ ohms to 240ish ohms. You might remove the wire at the tank and measure the resistance. The reading should be stable if the tank is not sloshing and be somewhere between these points depending on the amount of fuel. I don't remember which is the full reading; doesn't really matter. <br /><br />The ignition sw can be turned on with the wire off and the gauge will read one extreme (E or F) and then momentarily touching the wire to ground at the tank (sendiing unit disc should be at ground potential) will make the gauge read the opposite. Movement to both extremes should be rapid and smooth. This checks out the gauge. Turn the ign back off (might forget).<br /><br />Mark

 

[KCMILLS]

Re: erratic fuel gauge

thanks for the reply

 

[swist]

Re: erratic fuel gauge

Most boat fuel tank sensors are not the highest-quality equipment around, considering the stresses they have to endure (the float arm can really swing around violently in a rolling, pitching small boat). But I've never had any luck finding one of superior construction (or a better/different technology).

 

[Texasmark]

Re: erratic fuel gauge

swist, <br /><br />Go to your friendly John Deere Tractor Dealer/Supply house. Guarantee you that they have a different mouse trap for about $65 which is not unreasonable considering and it is setup on the 30-240 ohm standard resistance range.<br /><br />If they give you a blank stare tell them to look in the fuel tank breakdown for a 4010 (model tractor).<br /><br />Mark