FlyfishTXID Posted July 29, 2016 Report Share Posted July 29, 2016 I am going into my fourth year of owning my mav and have already had to clean my carbs twice. The most recent time, I found roughly 2 gallons of water in my gas tank. It is possible that I received bad gas, however, I suspect that there may be water getting into my fuel system when I run or wash the boat. Does anyone have experience with water getting in to their fuel system? Are there common risk points to check? Does anyone replace the o-ring on ther gas cap periodically? Thanks for the help! Link to comment Share on other sites More sharing options...
MuddyBottomBluz Posted July 29, 2016 Report Share Posted July 29, 2016 Here is what I do...Buy a mason jar full of moonshine, drink the moonshine, which by the way is the best part of the whole process, and then save the mason jar. The next time before you fill up put some gas from the pump in the mason jar swirl it around and inspect for water or phase seperation (milky looking gas). If it is good fill up and then do it again at the end of the fill up and inspect the last of the gas that entered the tank. And yes I replace my gas cap O-ring anually! A quality water seprator with a clear bowl is always beneficial. I had a bad experience where I got phase seperated gas and put it in my boat and truck unknowingly. Ruined a fishing trip and fried a fuel pump in my rear tank all in one trip, thank god for dual tanks. I swore it would never happen again! Link to comment Share on other sites More sharing options...
fishmanjj Posted July 30, 2016 Report Share Posted July 30, 2016 Are you buying non-ethanol marine gas ? Two gallons in one tank full is a lot of water ...a fuel / water separator can't handle that much at one time. I'd say either the fueling station where you bought from has water getting into their tanks, or you possibly have some water intrusion within your boat. I'd bet it's the source of where you buy the gas. If you had that much water getting in your fuel tank while fishing, you'd have fuel getting out also, and you would smell it. Link to comment Share on other sites More sharing options...
SCFD rtrd. Posted July 30, 2016 Report Share Posted July 30, 2016 Two things to look at. First, change the O-ring on the gas cap. That's cheap and easy. Then, access the fuel vent hose. If the hose runs downhill from the vent to the tank, that might be the source of water entering the tank. Water enters the vent and hose from waves splashing against the side of the boat and from washing your boat. Change the vent first. Buy a vent that has a 90 degree turn and install the vent with the barbed end pointing up, toward the gunnel. You'll probably have to buy new vent hose also. Install the hose to the vent barb so that the hose runs up toward the gunnel as far as possible, then turn the hose down to the tank. Essentially you are making a reverse trap with the hose. This keeps water from easily entering the hose. You would have to hold a garden hose right on the vent to force water into the system. Link to comment Share on other sites More sharing options...
FlyfishTXID Posted August 8, 2016 Author Report Share Posted August 8, 2016 Thanks for all the tips! This weekend I got all the old bad gas out of the system. I checked my vent line and it was already routed as SCFD recommended so I am pretty sure I just got a batch of bad gas. I put good gas in(checked with mason jar before I filled up) and took her out to the lake to run to make sure the carb cleaning solved my problems. Unfortunately, I'm still not out of the woods. When I first started run she got up on plane fine but was only topping out at 25 mph (normally top out at 30). I tried pumping the bulb and that helped a little bit as I could get up to 26-27. However, after repeating this several times, she just bogged down. I had the throttle all the way down and couldn't get above idle. My next plan is to replace the fuel pump and see if that helps but I just replaced the fuel pump last November so I'm not sure that is the problem. Does anyone have experience with this or similar issues? Amy recommendations for what else I can check? The motor is an '03 70 hp yamaha 2 stroke that had the powerhead replaced in 2013. Thanks so much for the help! Link to comment Share on other sites More sharing options...
LittleChief Posted August 8, 2016 Report Share Posted August 8, 2016 Inspect your spark plugs and change them out. I had similar issues and thought it was my fuel pump at first. I looked into the situation further and changed the spark plugs and I was able to get on plane no problem. Link to comment Share on other sites More sharing options...
East Coast Dave Posted August 8, 2016 Report Share Posted August 8, 2016 I'm having the same issue with my 2007 2 stroke 90 Yamaha. Not what in the gas that I know of but I just replaced the fuel pump. I'll let you know if it fixes my issue. Link to comment Share on other sites More sharing options...
SCFD rtrd. Posted August 8, 2016 Report Share Posted August 8, 2016 FlyfishTXID, when is the last time you replaced your gas hoses and bulb? Link to comment Share on other sites More sharing options...
FlyfishTXID Posted August 9, 2016 Author Report Share Posted August 9, 2016 @eastcoastdave - please let me know if that works. I an planning to replace fuel pump and spark plugs this weekend @SCFD The gas hoses and bulb were replaced about 4 years ago. I was thinking there may be an issue there but the bulb is not decompressed when I am running just not completely firm. Link to comment Share on other sites More sharing options...
East Coast Dave Posted August 11, 2016 Report Share Posted August 11, 2016 I'm having the same issue with my 2007 2 stroke 90 Yamaha. My issue seemed to be the fuel pump . I had it replaced and I didn't have any issues with it today I did check all my hose clamps etc to make nothing obvious was loose. I hope you figure it out. Those kind of things are frustrating. Link to comment Share on other sites More sharing options...
DonV Posted August 12, 2016 Report Share Posted August 12, 2016 JJ is right!! Two gallons is A LOT of water in a gas tank. Along with the other posts I'll share how water was getting into my gas tank and the fix. The inspection plate (8" pie hole) above the fuel tank was not sealed to the deck...at all...and water was leaking down, actually running down, on top of the fuel tank when it rained, washing the boat, etc.. Guess what's right below and down hill of the inspection plate, yep the sending unit for the fuel gauge. I took an eye dropper and dropped a few drops of water on the tank just uphill of the rubber gasket, as expected it disappeared right into the tank. May not seam like a big deal, however we all know how much it can rain in Florida. I took it all apart, drained the tank, cleaned the tank and put the sending unit gasket back with generous amounts of Permatex #2, then sealed the "water tight" pie hole properly and problem solved. Link to comment Share on other sites More sharing options...
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