ALMOST BLEW UP MY GAS TANK...READ THIS!

What's the back story? Did you just buy this boat or have you owned it for years and everything was normal before attempting to replace the sender?
 
scoflaw said:
OP might be elderly and what he thinks happened and what really did happen are 2 different things
Click to expand...
That would take some reasoning...
Some find it easier to hit the easy, I mean troll button.
 
Here's a thought for the ones that think this is entirely not possible.
Have you ever seen a burning Jerri can of gas? It doesn't explode. It burns like a big candle from the open filler and you can smother it with your bare hand.
Have you every heard of a fire popping up 50-100 yards from it's source months later because it has been smoldering in the roots? No atmosphere to supply oxygen but it must have received just enough to support the triangle.
Tanks are heavily baffled. My 100 gal tank has 5 in it. When I cleaned it after welding repairs, it actually took quite a while to get the fuel to run from one end to the other.
The OP had removed old fuel from a tank that had obviously been sitting for a period time. It likely also had a fair amount of condensation (H2O) collected inside the top of it. With a limited amount of heat, do you think it may be possible the molecules separated at a slow enough rate to support a candle? He had hot gases escaping from the vent. You assume he is making that up? He walked away from it for the night after deenergizing power sources.
I am not saying this how it happened, but offering possible ideas. The kind that make forums like these beneficial to all that read them, or not.
If this did happen, which I believe is a possibility, discrediting the OP will only run them off and nothing will be learnt.
If you think this is unreasonable and have nothing but insults to add, why do you bother?
 
Assuming the accuracy of the events, this is very interesting. We know the vapors from the fuel actually burn, not the liquid. Fuel flashes off/evaporates at a much lower temp than water. If the fuel sender was wired such that it heated to the minimal temp to ignite the fuel vapors, as long as the pressure did not build in the tank, and the tank temp stayed low enough, it could have “quickly evaporated” the fuel.
I have read all the postings and believe this could have happened, but the sender would have to have been wired with some type of low level dead short - not enough to burn a wire, burn a fuse, or trip a breaker, but enough to generate enough heat to ignite the evaporating fuel.
My take away: with our old, previously owned boats (like my 1989), always verify electrical wiring when replacing parts since we don’t know what was done before.
Great story. Useful info. Keep us posted.
 
scoflaw said:
OP might be elderly and what he thinks happened and what really did happen are 2 different things
Click to expand...
Aren’t you getting up there in years as well?
 
scoflaw said:
OP might be elderly and what he thinks happened and what really did happen are 2 different things
Click to expand...
There are WAY too many tangents here.
The amount of gas boiled is strange to me. I left the boat for overnight. The use of poly tanks for a ground wire is obvious.
I simply asked if anyone had this happen to them. I didn't ask if anyone thought I was crazy. SMILE.
I just got off the phone with my Master Electrician pal in South Carolina. Aluminum wire is no longer allowed in houses due to additional resistance.
The aluminum tank also acts as a diode due to its resistance, meaning it keeps voltage flowing in the right direction. When I added a jumper from the ground of the sending unit to the ground terminal of the gas tank, I bypassed the resistance barrier of the gas tank. Voltage flowed backwards thru the gas tank and heated it up.
The discussion of how much gas evaporated is a rat hole. I can't solve that mystery.
I simply know what I did and now I know why it happened. Now the solution may be disputed by some very good, knowledgeable, folks. Granted it is a theory backed by experience.
I am trying to go the extra mile to support the validity of my experience.
One gentleman asked for pictures.
Aluminum tank access area with grounding terminal and hole for sending unit.

upload_2020-10-26_17-10-56.png


Pictures are being erased. I will post one at a time.
Please read the explanation above given by my Master Electrician friend. There was plenty of gauge wire to heat the tank, and plenty of amperage in two batteries to do the job. Also, the current flowed backwards as explained.
I will post one picture at a time.
 

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Aluminum is not used in houses because the connections were corroding causing resistance and heat not because aluminum wire adds resistance. Also aluminum wire is still used from the street into the breaker panels and when wiring stoves and other high current draws but you need to use a anti corrosive paste to prevent corrosion and a high resistance connection!
 
20201024_103056.jpg

Old sending unit and new damaged sending unit
 
20201023_101212.jpg


Hand pump used to remove aluminum sludge after tank heated
 
You speak of voltage of which there should be none. The sending unit is a variable resistor on the ground wire. 1 wire from ground to the unit and the appropriate resistance measured in ohms is sent to the gauge through the pink wire. So where did the power originate from?
 
20201026_150806.jpg


Collected approximately 1 pint of sludge shown here in gasoline
 
20201026_150837.jpg

Vent hole below filler where hot gas fumes escaped warning me of the problem. I cut off all power and left the boat for overnight.
 
scoflaw said:
You speak of voltage of which there should be none. The sending unit is a variable resistor on the ground wire. 1 wire from ground to the unit and the appropriate resistance measured in ohms is sent to the gauge through the pink wire. So where did the power originate from?
Click to expand...
Please re read reply #68. My Master Electrician buddy handles Industrial electrical problems for BMW in Greenville, SC.. He spent a year in Afghanistan overseeing electrical installations for the defense dept.
And, he owned a 1980 24 ft SeaRay before he went overseas.
 
Thornton69 said:
Here's a thought for the ones that think this is entirely not possible.
Have you ever seen a burning Jerri can of gas? It doesn't explode. It burns like a big candle from the open filler and you can smother it with your bare hand.
Have you every heard of a fire popping up 50-100 yards from it's source months later because it has been smoldering in the roots? No atmosphere to supply oxygen but it must have received just enough to support the triangle.
Tanks are heavily baffled. My 100 gal tank has 5 in it. When I cleaned it after welding repairs, it actually took quite a while to get the fuel to run from one end to the other.
The OP had removed old fuel from a tank that had obviously been sitting for a period time. It likely also had a fair amount of condensation (H2O) collected inside the top of it. With a limited amount of heat, do you think it may be possible the molecules separated at a slow enough rate to support a candle? He had hot gases escaping from the vent. You assume he is making that up? He walked away from it for the night after deenergizing power sources.
I am not saying this how it happened, but offering possible ideas. The kind that make forums like these beneficial to all that read them, or not.
If this did happen, which I believe is a possibility, discrediting the OP will only run them off and nothing will be learnt.
If you think this is unreasonable and have nothing but insults to add, why do you bother?
Click to expand...
Thank you.
I hope my pictures and supported explanation add some validity to my story.
 
FredM said:
Please re read reply #68. My Master Electrician buddy handles Industrial electrical problems for BMW in Greenville, SC.. He spent a year in Afghanistan overseeing electrical installations for the defense dept.
And, he owned a 1980 24 ft SeaRay before he went overseas.
Click to expand...


Fred,

I have stayed out of this thread because frankly because we have never seen anything like this. So....just for clarity is this where you ran the grounding strap from the sender to? If so.....there is no electrical difference between screwing the sender in place and attaching a ground wire to this location.....none. There is no resistance, power reverse or any other electrical fantasy other than a grounded connection.

Now if somehow you hooked up a 12volt power wire to the sender....that could get interesting but grounding the sensor mounting screw to the ground terminal would have no effect.

One of the things about CSR is that the folks here know boats inside out. If something shows up we have NEVER seen before.....that means that it is highly unusual.

I realize you are trying to explain it and cite other experts and actions that you have taken but something else caused the tank to flash....if that is what it did and you are lucky to be alive.

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