defective wire to gas tank

T

tomengland

New member
C-brats: Long time reader and first time poster. My brother and I are trying to fix my dad's wiring to his starboard gas tank. Last summer I was trying to find out why the starboard trim tab light on the switch does not work. I was following the wire to the trim tab and noticed the second problem. The insulation on the wires going to the tank sensor module were gone. The port side tank wiring was fine. What would cause the wiring to go bad? i tried to have the marina mechanic look at last summer, but he was not interested in the project. Did the wiring go bad because of a faulty ground? I would like to try to get the problem diagnosed and corrected before the start of the boating season which is only 5 months away. I am not very mechanically savvy but my brother is an engineer so I hope he can figure it out.

Tom England
09 C-dory 26 venture
 
If insulation was gone , perhaps a rodent had it for lunch . We have seen this in boats in storage .Not sure if you're saying insulation was gone so it shorted ,or conductor [copper] were gone .
Marc
 
I agree with Marc, but it is also possible that there has been corrosion. There should be two wires: one to the sensor plus and one ground. The sensor wire is normal pink, but it might be red. If the wire is marine (tinned) as Brent suggests it should be, than you can just crimp on a new ring connector for both wires. I prefer the heat shrink, adhesive connectors. If you cannot find those, then a regular marine connector, and liberally use "Liquid Tape" over the fittings.

Many of the C dorys have plastic tanks, and one can either look at the center to see the fuel level, or some cut the fiberglass piece in front of the tank with a router, to allow one to see the fuel level.

A few boats had aluminum tanks, some with two smaller, and a few with a much larger single tank.
 
The insulation on the wire is very brittle and friable. It is almost like it over heated. The tanks are aluminum and at least 3 feet of wire is affected. Thanks for the info.

Tom England
Winona MN (on the banks of the frozen Mississippi River)
09 c-dory 26 venture
 
tomengland":366gw758 said:
The insulation on the wire is very brittle and friable. It is almost like it over heated. The tanks are aluminum and at least 3 feet of wire is affected. Thanks for the info.
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Definitely sounds like a short. Replace the wire with marine grade, same gauge as before, and look for places where the insulation may have been abraded off. You may have to replace the entire run. Cover those areas with chafe protection. Split loom is one choice. If the wire was unsecured and was whipping around, that could cause abrasion. Rule of thumb is to secure the wire inside split loom every 20 inches or so. I assume this wire would not have been immersed in bilge water, yes?

Split loom comes in various diameters, and is a useful way to bundle wires headed the same direction, securing the bundled wires within the loom. At the marine store they should have the hardware you need. Avoid spiral wrap. Huge PITA to install, even worse if you want to replace a wire or add one to the wrap.
 
To add to Dave's and other's posts, I would definitely check out all of the wiring to both tanks over its entire length and your best bet may be to replace it all. I like the wire which has the heavy vinyl outer sheath, which encloses the two smaller wires. There is minimal current thru these wires, and you could get away with very small wire, but I probably would use #16 or #18, just for the substance.

I may have missed what year the boat is. But if the wiring is over 15 years old, you may want to replace much of the wiring, and at 20 years I would seriously consider rewiring. (Some boats may be fine at that age, but I have seen many with very brittle insulation, and potential problems as the wire ages. A lot depends on conditions of storage.
 
This might be a long shot. Where are your batteries? Maybe acid reflux(sic)
Just a thought since those sender wires are not usually a problem. I thought maybe a batteries are over charging or were over filled.This could be a problem if they are over top of your fuel tanks which mine are. I switched to the AGM no need to add water or deal with battery acid anymore. Maybe check the fluid level of your batteries. That might be a clue.
D.D.
 
DD: The battery idea is interesting. On the venture the batteries are located in a hatch between the two gas tanks. Another observation last summer I noticed the batteries when hooked up to shore power seemed to hot when I went to try on the battery switch in the hatch. I took dad to replace the batteries this spring. Maybe the battery is the culprit. As far as the first problem (trim tab switch light is still not working on the starboard side) any thoughts on this problem? C-brats are great!!! Thanks for all the useful advice. I am on call this weekend so unable to drive over to parents to investigate further.

Tom England
09 C-dory 26 venture ("SheSayNo)
 
Another observation last summer I noticed the batteries when hooked up to shore power seemed to hot [/quote said:
If your batteries are hot to the touch when being charged they are probably being over charged. This will cause excessive boiling which can cause acid to escape from the fill caps. This may have caused your wiring problem like DD mentioned. High temps can also warp the lead plates causing problems(internal shorts). Acid covering the top of the battery can also allow voltage to leach between cells causing problems.

I would check the charging voltage with a digital voltmeter. It should not be higher than 14.4 - 14.6. Also check the fluid and if you suspect some has boiled out onto the top of the battery, wash it with baking soda and water.

Regards, Rob
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If hooked up to shore power, and the battery charger was on/the batteries too hot, suggests that there is an issue with the battery charger. As Rob notes the digital volt meter is your tool to use. I have not had good luck with the Guest battery chargers which come with the boats. The charger should float the battery at about 13.3 to 13.6 volts. This should not cause the batteries to be hot. When in absorption or bulk phase, the voltage may be higher. As Rob noted, outboards are not well regulated, and often put out voltage in the low to high 14.4-6 volts, which is the upper limits for lead acid batteries charging voltage.

There could be many different issues with the trim tabs. First see if they are working properly--it may just be a bad bulb, sensor, or wiring to the bulb or sensor.
 
We replaced about five feet of the starboard wire to the gas tank module. The module was not defective. We were able to follow the wire to the grounding bar and the connectors were tight and secure. We also found out the starboard battery was bad. All batteries were replaced. Hopefully the problem is corrected. The starboard trim tab had a bad coil in the upper hinge. The customer service at bennett trim tabs were very helpful and the part was ordered and installed. Thanks for the help c-brats.
 
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