Water in diesel fuel tank

[RetCO]

I recently left my boat with the fuel tank fill cap off prior to some heavy rains. So obviously I've got water contamination. I ran the engine for about a half hour before I realized that there was water in the fuel.
I assume I'll have pump out all the fuel I'm able to and put in fresh fuel.
I'm wondering if any damage has already been done and if there is any other things I can do at this point to minimize the problem. Appreciate any help.
(sorry Barry).

[sailingdog]

If you have a water/fuel separator filter, then you probably didn't do any damage. If you don't, you should probably get one... It really depends on whether the fuel pickup tube was in the water or in the diesel. If it was in the diesel, you may not have done any damage. If it was in the water, the engine wouldn't have run and you would have probably damaged the injectors.

You won't have to pump out all the fuel, but adding a biocide and trying to pump out the bottom of the tank to remove the water would probably be a very good idea. Capture the fuel and pour it back into the tank using a baja filter or something similar to separate out the water.

[Banshi]

You should check the water separator to insure it is not full, your diesel won't run once it is. Water can do extreme damage (it does not compress well and is rough on injectors) which is why the water separator is used. Depending on how much you think it might be there are additives that will get rid of it without removing all the fuel already in the tank. It certainly can't hurt to dump the old fuel but that still may not get it all unless you can get it completely dried out inside. Water often gets in the tank from humidity in the air and a tank that is left only partially filled all the time allowing it to condensate inside the tank. So it is likely there is always some in it anyways.

[MIKEMCKEE]

there is a paste you can buy at most fuel container site's that you put on a stick and when you put it in the fuel tank's depression area by the pickup tube, it will turn from brown to red, letting you know what amount of water you have in your tank. I've used it for a few years and one 5 oz tube goes a long way.

Good Luck,

Mike

[svindigo]

You'll know when the water gets to your engine because it will stop running so you should be OK FOR NOW. Agree with the earlier advice re: fuel water separator (if you don't have one, do not pass go or WM and get one now, pumping out the bottom of the tank vs emptying your tank will also work. Particularly if you have large tank(s) (We have 250 gallons and I have pumped water off the bottom with a hand bilge pump and hose extension with success. Pls don't ask why, it's a very long story!)

After doing all of the above, pay close attention the next time you are motoring in lumpy conditions as some residual water may slosh by the fuel pick up tube and end up in the Racor filter you bought. (you did buy it right?)

I think you are OK and future trouble is easily avoided. Especially if you remember to put the fuel cap back on!

Cheers,
Ike

[hellosailor]

"there is a paste you "
Thieving paste, so called I'm told because it "steals" the water. One of those old-fashioned products that may produce a baffled stare from the younger help at the counter.[g]

[NorthUp]

the paste is called Kolor Kut, and its made in Texas. it just discloses the presence of water in the fuel, it does not remove it.

[xort]

I love my fuel polishing system!!!

It has a tube at the very bottom of the fuel tank that runs to a small pump. The pump pushes the fuel through a Racor 500 filter system with a 10 micron filter and then back in at the top of the tank. Does 50 gallons in an hour. A beautiful thing!

[Rockter]

Open the inspection hatch at the top of the tank and shine a flashlight in there. If there is water in there it will often look like liquid mercury as it reflects the light at the oil-water boundary. If it's there, get a wee pump (a motorised oil-change pump with a fine tube will do) and suck it out of there.
You can add some biocide also if you want.
Water is bad news in there. It causes endless problems, particularly the build-up of a strange, slime-like polymer.
I trust that there is an inspection hatch. If not, then you will have to take out the fuel pick-up tube and suck it out from there.

[EO32]

Originally Posted by Banshi

Water can do extreme damage (it does not compress well and is rough on injectors)

I don't think it has to do with compression, since diesel also does not compress. I would think it would have to do with the lubrication that diesel provides.