# Yamaha F300 water in fuel and VST



## panhandlephinsphan (Aug 25, 2008)

Recently my relatively new, low hours F300 Yamaha stopped running. I have been wrestling a water in fuel issue- which I think is finally fixed. Every few trips the alarm would go off that there was water in the fuel at the motor. I would shut down, empty the fuel water separator in the bilge, then pull off the cowling, and take off and drain the fuel water separator at the front of the motor- and move on. There was one trip that it was too rough to do any of that and I had to keep running. When I got back i did my usual drain of the 2 fuel water separators and then ran the motor for a while. Well, there is a VST (tank) around the high pressure fuel pump that I had no idea about. There is also a drain line attached to it. If I had known about that I would have drained it as well and never been in this position.

Bottom line, I ran the motor when the fuel water separators were full and did not drain the VST afterwards and it caused the connectors in the VST for the fuel pump to corrode

NOT covered under warranty (and I would not have expected it to be- Yamaha did not cause this problem). Will fix it myself if it ever happens again, but I fixed the water issue and also installed a fuel water separator in the bilge with a clear bowl so I can see it and drain it before it ever reaches the motor

I hope others can read and learn from this. 

SIde note: Posner Marine has been awesome to work with. Prompt and fair.


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## sealark (Sep 27, 2007)

You need to find out where the water came from and fix that first. Then take the sending unit off the tank and pump out the low end corner of the tank to remove any remaining water from the tank. Or your water will continue to haunt you.


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## panhandlephinsphan (Aug 25, 2008)

I think we fixed that part. THe fittings and seal/gasket on top of the tank needed to be repaired/replaced/maintenance. Done. ANd I replaced the pickup tube, and all hoses/fittings/housings/filters from the pickup tube to the motor with new lines. We then pumped out the remaining fuel in the tank through a fuel/water separator. I never drained the VST unfortunately. SInce doing all of that replacement we have not not the water alarm go off again and I have poured the contents of my bilge fuel water separator into a jar to see how it looks- so far so good!


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## captken (Feb 24, 2008)

*Better heed what Sealark said.*

Find where the water is coming from or you will continue to have the problem. Yes, I have gotten bad fuel at marinas and gas stations but precious few times over lots of years. 

New boat or did you put a new engine on an older boat?
Check to see if filler vent gets hit by occasional spray in certain sea conditions. 
Can you get to the top of the tank? Look for corrosion or a crack. 
Is there water standing on top of the tank?

I had a leak around the sending unit once and wound up replacing the tank. Expensive and a serious painintheass job.

A big Racor filter with a clear settling bowl is an absolute must on my boat.

Many years ago, I had a gizmo that was basically a long skinny cloth bag with some sort of water absorbing chemical in it. It had a weight in one end and a long string on the other. Drop the bag into the tank (give it some slack so it can move around)and run a while. When you pulled it out, if it had water, you'd know it because it would be noticeably heavier. You had to dry the bag over night then do it again and again.

Fix the problem or you will call Sea Tow and maybe buy a new engine. This is a really serious problem.


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## sealark (Sep 27, 2007)

You still need to take sending unit off and raise th bow and put a small list on the boat then put a tube from a pump or siphon in the lowest corner and pump the remaining water out. That pickup tube end is screaned and is up off the bottom of tank.


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## panhandlephinsphan (Aug 25, 2008)

Bought a hand pump at harbor freight. Pulled tank open, pitched boat to get all of the fuel in one corner and sucked it all out and through a water/fuel strainer funnel.

Starting with a water free tank. 

If I get any build up in my clear bowl in the bilge then I know there is still an issue.

Fingers crossed


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## sealark (Sep 27, 2007)

Sound good make sure you seal the sending unit so no water gets in there and check the fill cap and the overboard vent for possibility of water intrusion. You should be ready to go fishing then.


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## Ocean Master (May 20, 2008)

Everyone should be using Racor filters and heads with the clear bowl. How else are you going to know if you have water?


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