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View Full Version : Water coming in through gas vent


jdmcraft
08-16-2010, 10:02 PM
Hi, I'm having issues with my 1990 Tristar. It keeps getting water in the gas tank. I've had the carb rebuilt, the water/fuel, separator replaced, the tank emptied (twice). The boat runs strongly for hours but it seems that the water/fuel separator cannot keep up and eventually it gets waterlogged and dies. I've just drained the tank myself (I'm fed up with the dealer and local shop). I unhooked the hose that goes from the vent (under the fuel fill) and put it in a bucket and sprayed the vent with a garden hose. There was a significant amount of water that came in throught the gas vent. I notice that when I'm cruising at medium speed, 20-30 mph, the water splashes right up into the vent area especially when I turn to the right. Has anyone ever had a similar issue with your tristar or any mastercraft for that matter? I can't find anyone with a similar experience.

As another test, I'm planning to connect a hose to the fuel tank where the vent hose would normally go and just fasten it so it just vents higher over the gunwale so no water will get into the tank again (if that's where it is coming from). I will then leave the hose going from the gas vent outlet on the side of the boat down into a bucket. I will take the boat out and do some hard turns and see if water fills into the bucket while the tank vents safely over the side. When I get home I'll check the water/fuel separator to see how full it is. Ok. Thanks for listening. Please let me know if you have any thoughts.

Thrall
08-17-2010, 03:55 PM
I know the air/fuel separator like skidim sells works well for keeping fuel from sloshing out the vent when the tank is full. WOrked great on my '96 but I never had a problem with water coming in. Not sure if it's designed to keep water from coming in though.
They're $80 so I'd verify it will work first.
Could you put a loop or high point in the vent hose? Cheap solution?

etduc
08-17-2010, 05:43 PM
I have owned a 1990 Tristar, I know want you're talking about. For others information, the gas tank is located in front of engine, were some ski lockers are located. The hose should turn-up, above the vent port (gunwall) as high as possible, before going to gas tank.

Another tip, requires re-installation of the vent. Rotate the vent, slightly towards the stern.
Then do the loop, like above. (This won't help, if you submarine, yout boat. :))

jdmcraft
08-17-2010, 06:14 PM
Putting a high point in the hose seems like a great idea...I don't know why I didn't think of that. I'll try that. I think I could also get a vent with a 90 degree neck (inside the hull) and turn it upward and combine that with a hose that goes as far up under the steering column as possible. Thanks to both of you. I'm still going to do my test out on the water to see if water is coming in through the current vent under those conditions.

oldairboater
08-17-2010, 06:17 PM
I would try to replace that vent line and take it high up so the vent is lower then the hose by making a peak in it. The higher the peak and the longer the hose the less likely water will be forced into the tank. Someone suggested it while I was on the phone.

jdmcraft
09-20-2010, 10:40 AM
Hi everyone,

Does anyone know of an online parts dealer where I may buy the proper tank for my Tristar? I'm still having water/fuel issues. It is definitely not coming in through the fuel vent. I think it may be coming in through the top of the fuel tank. I can see that a previous owner tried to water proof it with some sort of tar like substance. It was slathered all over the sending unit. I'd like to buy a new tank and rule out my tank as being the problem. However, I cannot find a tank online. I don't want to go to either of my local dealers (skipper buds and redline) they seem crooked to me.

thatsmrmastercraft
09-20-2010, 11:40 AM
Hi everyone,

Does anyone know of an online parts dealer where I may buy the proper tank for my Tristar? I'm still having water/fuel issues. It is definitely not coming in through the fuel vent. I think it may be coming in through the top of the fuel tank. I can see that a previous owner tried to water proof it with some sort of tar like substance. It was slathered all over the sending unit. I'd like to buy a new tank and rule out my tank as being the problem. However, I cannot find a tank online. I don't want to go to either of my local dealers (skipper buds and redline) they seem crooked to me.

Midwest Mastercraft Crystal, MN http://www.waterskis.com/
http://www.chicagomastercraft.com/
http://www.bayareawatersports.com/

oldairboater
09-20-2010, 11:49 AM
How is water getting in but gas is not getting out? My tank is sealed. There should be gaskets where the sending unit is. The sending unit should be sealed. The gas filler tube should have clamps on it to seal it. The vent tubing should be peaked to keep water from flowing up hill to enter the tank. I would not put a check valve in the fuel line but I would make sure that my vent line was higher in one spot then my vent to keep water from being able to flow down hill to my gas tank.The screw in gas cap on the hull should have a gasket. How are you getting enough water in a tank to be a problem?

wheelerd
09-21-2010, 02:23 AM
I had the same problem with my '91 TriStar. Like a previous poster suggested, I rotated the vent towards the stern. Also, after comparing it with some other vents, I realize that the lower lip on the vent was broken off which also allowed the splashing water easier access. For good measure I scrunched up a small piece of rag and stuck it in the vent -- tight enough so it wouldn't fall out but not so tight it prevented air from passing. It wasn't noticeable unless you looked directly at it.

tommyboy
06-18-2012, 01:55 PM
I have the same problem with my '89 220. I get enough water in my tank every couple weeks to cause my boat to stop working and for the life of me cant figure it out. It has to be the vent, I smell no gas leaking from the tank so I don't believe there is a leak.

Is it really that the vent is pulling in enough water to cause this issue? Do I simply need to put a high enough P trap on it to prevent water from back flowing in to the tank?

One other question, is there supposed to be a cover over the vent on the side of the boat? I simply have an open hole with a screen.... Am I missing a cover?

Thanks for any help.

wheelerd
06-18-2012, 07:20 PM
That's likely the problem. The previous owner of my TriStar told me that he would shove a tiny wad of rag into the vent to stop water from getting in. I didn't believe him . . . but I should have.:( My first couple of outings with the boat, sure enough, I got water in the tank. I started plugging the vent like he suggested and then it was OK. As I mentioned above, eventually I turned it so it was facing the stern and then all was well.

Yes, there should be a small chrome bullet-shaped cap on the vent. It's pointed at one end and open at the other. On most TriStars I've seen the open end faces down and therein lies the problem. (There's another opening in the hull close to it but that's the bilge pump outlet.) Sorry I don't have close up pics to illustrate.

michiganTristar
06-19-2012, 11:01 PM
Similar problem here, thinking its water in the tank. wondering what your guys symptoms are when this happens, like will it still idle but not run strong or just not start at all?

Here is what i changed, rebuilt carb from dealer, new fuel pump and filter, new water separator, new spark plugs, and new starter. it will start up everytime i take off and has power but as soon as i come off the throttle and hit it again it has very little power at all and i have to idle back to the dock.

Has anyone had issues like this, its an 89 tristar open bow with a 351. I am at a loss of where to try next?

wheelerd
06-19-2012, 11:48 PM
When I had water in the tank it would start running rough and I would have to pump the throttle to keep it going. Eventually it wouldn't run at all. The final time before I fixed it for good, the boat stalled on me in the middle of the lake. I pulled the rubber fuel line off the pressure side of the fuel pump and put it into an empty plastic pop bottle. I hit the starter for numerous short bursts until most of the water was pumped out of the tank. Eventually I got the motor running before the battery was completely dead and got back to shore.

Your problem may be a bit of water but it sounds more carb related. I might want to check the power valve in the carb even though it's been rebuilt. Is the carb the stock Holley 4160? There are other culprits to track down too -- vacuum leaks, choke sticking, sticking floats (although that usually causes flooding),

wheelerd
06-20-2012, 06:49 AM
Thinking further . . .
Are your accelerator pumps giving a little shot when the throttle advances from idle? You should be able to see it when you look down intro the throttle bores from above. It should be an even, fine mist.

wheelerd
06-20-2012, 06:53 AM
Yes, there should be a small chrome bullet-shaped cap on the vent. It's pointed at one end and open at the other. On most TriStars I've seen the open end faces down and therein lies the problem. (There's another opening in the hull close to it but that's the bilge pump outlet.) Sorry I don't have close up pics to illustrate.

I did find a pic. If you look closely you can see a little piece of blue shop towel sticking out of the vent.

michiganTristar
06-21-2012, 08:35 AM
To test if it was water in the gas I brought a 5 gallon gas can with me with fresh gas in it, put the fuel line in it and it ran like a champ no problems at all. So next step was hand pumping out 22 gallons of fuel out of the tank, putting 5 gallons into the tank running it dry until it died and then filled it up with fresh gas. It runs perfect now, good news is that the carb, starter, fuel pump, filter, water seperator filter, and spark plugs have all been relaced now haha. It sure was hot hand pumping out all that fuel in 98 degree sun.