Water in Fuel Tank - Moderated Discussion Areas

  ContinuousWave
  Whaler
  Moderated Discussion Areas
  ContinuousWave: Post-Classic Whalers
  Water in Fuel Tank

search | FAQ | profile | register | author help

Author Topic:   Water in Fuel Tank

tom976 posted 07-20-2012 11:55 AM ET (US)
I have a 1997 230 Conquest with a strange problem. I am getting water in the gas tank and I am stumped figuring out where its coming in from. Fenerally, before I go out, I take a sample from the fuel-water seperator to see the fuel condition. I remove as much [fuel] as I can from the seperator with the boat running then, it is fine. I should mention that last year I also completely emptied the tank due to the same problem and started from scratch.
The first thing I did was check the perko gas cap. I replaced the O-ring on it and thought all was well--nope. One weird thing: there appears to be some water under the cap. Not even sure how it is getting in there. I ran a hose on it for 10 to 15 minutes, and not a drop or water inside [the filler cap]. I am suspecting the cap mainly because everything else is shielded from water and rain. So from where else can [water] be coming into the fuel tank?
Thoughts? Thanks
davej14 posted 07-20-2012 08:58 PM ET (US)
How about the vent hose or the seal on the fuel level sender? It has to be somewhere above the normal fuel level or you would be leaking fuel into the bilge.
jimh posted 07-22-2012 11:16 AM ET (US)
In general there are only three ways that water can enter the fuel tank:
--in suspension in the fuel you purchase; you pump the water into your tank when you buy fuel;
--by condensation of water vapor in the empty space above the fuel in the tank as a result of diurnal variation in the air temperature of that space; while this source is often touted as being able to manufacture large volumes of water, there is doubt and uncertainty that this method could produce a substantial volume of water in the fuel tank of a Boston Whaler; and,
--by a leak in some part of the fuel system.

If you are confident there is no water in the fuel you are buying, we can rule out that source. If your boat is operated in the usual manner with the usual changes in temperature from day to day, we can rule out condensation forming large volumes of water in the tank. That leaves a leak.
It would be unusual to have a leak in the fuel tank in a 1997 Boston Whaler boat due to general deterioration of the fuel tank with age. The fuel tank is only 15-years-old. Generally aluminum fuel tanks have a longer service life than 15-years. However, if your boat was used is saltwater, if the fuel tank was chronically wet with saltwater, or if the fuel tank was left to sit with a load of bad fuel that contained enough water to have the water separate from the gasoline, the tank could have prematurely deteriorated. The best method to assess the tank condition regarding leaks is to perform a pressure test. Contact the tank manufacturer for advice on the maximum test pressure. Often the fuel tank will contain an identifying label which will specify the maximum test pressure. If that is still visible, be guided by that specification.
Robert V posted 07-23-2012 07:27 AM ET (US)
Jim took the words out of my mouth, a pressure test would be the best way to resolve the leak problem.
tom976 posted 07-23-2012 01:27 PM ET (US)
With this boat there doesnt appear to be a vent out of the tank in the normal way. [There is] no vent cap on the hull. It looks like it is vented through the cap. I am going to pull out the side panel by the fuel cap and see what's in there. I was thinking about corrosion. I dont have any saltwater in the bilge. When there is water in the bilge, it is there due to rainwater. I washed down the boat yesterday and noticed a bit of water on top of the gas tank. Looks like it is leaking through the round deck hatches. I cleaned off the seals and put it back together. [Give me a] clue where I can source new seals for these 8- or 10-inch round hatches.
I guess pressure testing the tank in the next option, never did that one before. Would like to be able to do this WITHOUT unscrewing the deck. Thoughts? Thanks--Tom
jimh posted 07-23-2012 10:24 PM ET (US)
The round deck access plates are typically made by BECKSON. See
http://continuouswave.com/ubb/Forum3/HTML/019387.html
HawaiianWhaler posted 07-24-2012 01:47 AM ET (US)

quote:
tom976 - With this boat there doesnt (sic) appear to be a vent out of the tank in the normal way. [There is] no vent cap on the hull. It looks like it is vented through the cap.
Do you not have a "VENT, FUEL TANK, ¾" SS" (pc. 15, p/n 0859157) protruding from the starboard side of your hull approximately in line with the helmsman's chair and about a foot below the top of the gunwale?
Could that vent be the source of the water, either by its orientation having been changed somehow such that the vent holes face upward, or by having water shot upwards into it?
While the 230 Conquest hull assembly drawing clearly shows the above vent, the 230 Conquest cabin assembly drawing does also clearly show a (pc. 37, p/n 0868489) "DECKPLATE, GAS, W/VENT" so the gas cap itself may also be vented although it is not clear (at least to me) how that would be accomplished given its configuration and location. Perhaps the description "W/VENT" refers to the separate vent shown in the hull assembly drawing?
In any event, suggest you consider whether or not water is entering your fuel tank via the vent shown in the hull assembly drawing.
Robert V posted 07-24-2012 08:54 AM ET (US)
In addition to my previous post, check the gasket on the fuel sender located on top of the fuel tank (and any other top of tank penetrations). It should be accessible under one of the deck plates. Sounds like water may be entering the tank after it comes through your inspection plates. On the topic of deck plates, check the sealant installed around the deck plates, water can enter around that seal as well as the gasket. On my boat, I have cleaned the gaskets and used some lithium grease to lube the gasket material prior to re-installation. Hope you can find the water source, good luck with your project.
tom976 posted 07-24-2012 10:55 AM ET (US)
Thanks JimH for the info, I will get some measurements of my plates and see what they help we with. The seals have seen better days. What did whaler use to seal the outer edge of the deck plate to the fiberglass floor? I noticed the seals are pretty much shot after 15 years.
HawaiianWhaler, I took a look a the parts diagrams on the whaler website, there is no # 15 (vent) on the outside of the hull. The gas cap that I have is a self venting one. Weird that the vent is where I noticed the water collecting. One thing that I did was call Perko about it. Talked to a nice guy and he mentioned that about 15 years ago they had issues with these vented gas caps.
If they were installed in location where water could collect or continually be sprayed with water, it'll get in. Their fix was to install a gasket that raises the cap assembly about 3/8". They're going to send it to me for free. Nice customer service! I'll try that one.
Robert V, I am going to check that next. My sender has had better "sending" days. Not sure if its working correctly anymore so a replacement is going to happen shortly with that a new gasket.
Thanks for all the help to far. I just ordered a small pump to assist me in getting out the bad gas before I go out. I'll see how well that one works out.
Tom
HawaiianWhaler posted 07-24-2012 08:17 PM ET (US)
tom976 - It's strange that you see no vent, pc. 15.
Here's where I saw it: http://www.bostonwhaler.com/boat_graphics/electronic_brochure/Company94/ _56_74201043301PM.pdf
I thought to look for it because I have such on my Conquest 21 (the link above is to a 230 Conquest) and my fuel fill cap is non-vented (at least as far as I can see).
Nice that you got good help from Perko; hope that resolves your issue. Will the gasket just raise the vent opening 3/8", such that water deeper than that will still get in? Not likely that you'll have standing water that deep, but out here we occasionally take waves up against the side of the cabin that are 'deeper' than that. I guess momentary submersion like that shouldn't cause any issues since the vent on the side of my hull similarly gets submerged.
Aloha.

Hop to:

Contact Us | RETURN to ContinuousWave Top Page

Powered by: Ultimate Bulletin Board, Freeware Version 2000
Purchase our Licensed Version- which adds many more features!
© Infopop Corporation (formerly Madrona Park, Inc.), 1998 - 2000.

Author	Topic: Water in Fuel Tank
tom976	posted 07-20-2012 11:55 AM ET (US) I have a 1997 230 Conquest with a strange problem. I am getting water in the gas tank and I am stumped figuring out where its coming in from. Fenerally, before I go out, I take a sample from the fuel-water seperator to see the fuel condition. I remove as much [fuel] as I can from the seperator with the boat running then, it is fine. I should mention that last year I also completely emptied the tank due to the same problem and started from scratch. The first thing I did was check the perko gas cap. I replaced the O-ring on it and thought all was well--nope. One weird thing: there appears to be some water under the cap. Not even sure how it is getting in there. I ran a hose on it for 10 to 15 minutes, and not a drop or water inside [the filler cap]. I am suspecting the cap mainly because everything else is shielded from water and rain. So from where else can [water] be coming into the fuel tank? Thoughts? Thanks
davej14	posted 07-20-2012 08:58 PM ET (US) How about the vent hose or the seal on the fuel level sender? It has to be somewhere above the normal fuel level or you would be leaking fuel into the bilge.
jimh	posted 07-22-2012 11:16 AM ET (US) In general there are only three ways that water can enter the fuel tank: --in suspension in the fuel you purchase; you pump the water into your tank when you buy fuel; --by condensation of water vapor in the empty space above the fuel in the tank as a result of diurnal variation in the air temperature of that space; while this source is often touted as being able to manufacture large volumes of water, there is doubt and uncertainty that this method could produce a substantial volume of water in the fuel tank of a Boston Whaler; and, --by a leak in some part of the fuel system. If you are confident there is no water in the fuel you are buying, we can rule out that source. If your boat is operated in the usual manner with the usual changes in temperature from day to day, we can rule out condensation forming large volumes of water in the tank. That leaves a leak. It would be unusual to have a leak in the fuel tank in a 1997 Boston Whaler boat due to general deterioration of the fuel tank with age. The fuel tank is only 15-years-old. Generally aluminum fuel tanks have a longer service life than 15-years. However, if your boat was used is saltwater, if the fuel tank was chronically wet with saltwater, or if the fuel tank was left to sit with a load of bad fuel that contained enough water to have the water separate from the gasoline, the tank could have prematurely deteriorated. The best method to assess the tank condition regarding leaks is to perform a pressure test. Contact the tank manufacturer for advice on the maximum test pressure. Often the fuel tank will contain an identifying label which will specify the maximum test pressure. If that is still visible, be guided by that specification.
Robert V	posted 07-23-2012 07:27 AM ET (US) Jim took the words out of my mouth, a pressure test would be the best way to resolve the leak problem.
tom976	posted 07-23-2012 01:27 PM ET (US) With this boat there doesnt appear to be a vent out of the tank in the normal way. [There is] no vent cap on the hull. It looks like it is vented through the cap. I am going to pull out the side panel by the fuel cap and see what's in there. I was thinking about corrosion. I dont have any saltwater in the bilge. When there is water in the bilge, it is there due to rainwater. I washed down the boat yesterday and noticed a bit of water on top of the gas tank. Looks like it is leaking through the round deck hatches. I cleaned off the seals and put it back together. [Give me a] clue where I can source new seals for these 8- or 10-inch round hatches. I guess pressure testing the tank in the next option, never did that one before. Would like to be able to do this WITHOUT unscrewing the deck. Thoughts? Thanks--Tom
jimh	posted 07-23-2012 10:24 PM ET (US) The round deck access plates are typically made by BECKSON. See http://continuouswave.com/ubb/Forum3/HTML/019387.html
HawaiianWhaler	posted 07-24-2012 01:47 AM ET (US) quote: tom976 - With this boat there doesnt (sic) appear to be a vent out of the tank in the normal way. [There is] no vent cap on the hull. It looks like it is vented through the cap. Do you not have a "VENT, FUEL TANK, ¾" SS" (pc. 15, p/n 0859157) protruding from the starboard side of your hull approximately in line with the helmsman's chair and about a foot below the top of the gunwale? Could that vent be the source of the water, either by its orientation having been changed somehow such that the vent holes face upward, or by having water shot upwards into it? While the 230 Conquest hull assembly drawing clearly shows the above vent, the 230 Conquest cabin assembly drawing does also clearly show a (pc. 37, p/n 0868489) "DECKPLATE, GAS, W/VENT" so the gas cap itself may also be vented although it is not clear (at least to me) how that would be accomplished given its configuration and location. Perhaps the description "W/VENT" refers to the separate vent shown in the hull assembly drawing? In any event, suggest you consider whether or not water is entering your fuel tank via the vent shown in the hull assembly drawing.
Robert V	posted 07-24-2012 08:54 AM ET (US) In addition to my previous post, check the gasket on the fuel sender located on top of the fuel tank (and any other top of tank penetrations). It should be accessible under one of the deck plates. Sounds like water may be entering the tank after it comes through your inspection plates. On the topic of deck plates, check the sealant installed around the deck plates, water can enter around that seal as well as the gasket. On my boat, I have cleaned the gaskets and used some lithium grease to lube the gasket material prior to re-installation. Hope you can find the water source, good luck with your project.
tom976	posted 07-24-2012 10:55 AM ET (US) Thanks JimH for the info, I will get some measurements of my plates and see what they help we with. The seals have seen better days. What did whaler use to seal the outer edge of the deck plate to the fiberglass floor? I noticed the seals are pretty much shot after 15 years. HawaiianWhaler, I took a look a the parts diagrams on the whaler website, there is no # 15 (vent) on the outside of the hull. The gas cap that I have is a self venting one. Weird that the vent is where I noticed the water collecting. One thing that I did was call Perko about it. Talked to a nice guy and he mentioned that about 15 years ago they had issues with these vented gas caps. If they were installed in location where water could collect or continually be sprayed with water, it'll get in. Their fix was to install a gasket that raises the cap assembly about 3/8". They're going to send it to me for free. Nice customer service! I'll try that one. Robert V, I am going to check that next. My sender has had better "sending" days. Not sure if its working correctly anymore so a replacement is going to happen shortly with that a new gasket. Thanks for all the help to far. I just ordered a small pump to assist me in getting out the bad gas before I go out. I'll see how well that one works out. Tom
HawaiianWhaler	posted 07-24-2012 08:17 PM ET (US) tom976 - It's strange that you see no vent, pc. 15. Here's where I saw it: http://www.bostonwhaler.com/boat_graphics/electronic_brochure/Company94/ _56_74201043301PM.pdf I thought to look for it because I have such on my Conquest 21 (the link above is to a 230 Conquest) and my fuel fill cap is non-vented (at least as far as I can see). Nice that you got good help from Perko; hope that resolves your issue. Will the gasket just raise the vent opening 3/8", such that water deeper than that will still get in? Not likely that you'll have standing water that deep, but out here we occasionally take waves up against the side of the cabin that are 'deeper' than that. I guess momentary submersion like that shouldn't cause any issues since the vent on the side of my hull similarly gets submerged. Aloha.