Contaminated Boat Fuel

[gregcrameri]

Hi all,

I filled up 2 weeks ago with 70 litres of contaminated fuel. It was suppose to be premium unleaded, but what I actually got was a combination of unleaded petrol and diesel. The outboard motor was blowing a lot of smoke and I'm going to drain the fuel tank. The question I'm hoping someone can answer is… what affect would it have on the engine in terms of damage?

I have received mixed reports from 2 different mechanics. One mechanic is telling me it would have no affect as diesel is a lighter fuel with more oil and as a result it will just blow more smoke. The other mechanic is telling me to conduct a complete check on the engine. Any thoughts let me know?

[tuffy]

So the real question is - how much does a complete engine check cost vs how much is a complete engine.

When in doubt, check it out!!

Tuffy

[andrew399]

I know with cars it doesnt matter so much, but will cause a fair bit of pinging, but outboards seem to be much more sensitive...If i were you I would call site sponsor Huett Marine - and not just because he is site sponsor, that doesnt matter to me - but because this guy knows his stuff better than anyone I have come across. Trust me, he's seen it all!

[The Incredible Hull]

http://www.lmgtfy.com/?q=can+you+pour+deisel+in+petrol+engine

[BWV]

Hi all,

I filled up 2 weeks ago with 70 litres of contaminated fuel. It was suppose to be premium unleaded, but what I actually got was a combination of unleaded petrol and diesel. The outboard motor was blowing a lot of smoke and I'm going to drain the fuel tank. The question I'm hoping someone can answer is… what affect would it have on the engine in terms of damage?

I have received mixed reports from 2 different mechanics. One mechanic is telling me it would have no affect as diesel is a lighter fuel with more oil and as a result it will just blow more smoke. The other mechanic is telling me to conduct a complete check on the engine. Any thoughts let me know?

What type of engine is it? Carby? Injected? What was the mix ratio? How long did you run it for on the mixed fuel? Was the engine running ok other than lots of smoke, not miss firing or anything?

Diesel is heavier than ULP, diesel has a specfic gravity of .83 - .9 and ULP is around .73, so 1 cubic meter of D will weight approx 830-900kgs and the same amount of ULP will come in at 730kgs. The engine will blow more smoke as diesel is just an oil, but it is the first by product of ULP when it is refined.

Just drain the tank as you mentioned and fuel it up and take it for a run, but get a 3rd opinion just to make sure.

Edited May 19, 2011 by Whaler 255

[a boat]

Hi, as the guys have said a bit more info might help in particular "what is it". I have seen outboards survive doing this sort of thing and knowing more will help us help you.

Cheers,

Huey.

[gregcrameri]

Hi, as the guys have said a bit more info might help in particular "what is it". I have seen outboards survive doing this sort of thing and knowing more will help us help you.

Cheers,

Huey.

Thanks for the replies

It is a 2000 Model Johnson 175HP, 2 stroke outboard. As soon as it started blowing smoke I took it back to the mooring. It wouldn't have been running for longer than 5 minutes. Didnt seem to lose power just blew a lot of smoke and I mean a lot of smoke. I'm getting the tank drained tomorrow so will see how it goes with some fresh fuel and then I'll get it checked out.

[a boat]

Hi, if the engine was only run for that short amount of time no mechanical damage would of occured and this can be confirmed by compression and leak down tests. I would drain the fuel, fill with premium fuel (from another place) and also drain the carby bowls. I also would make sure the fuel hoses, fittings etc are tight and do not let that engine suck air, I would make sure you are proped to see about 5500 at WOT and I would use as a min XD-50 in her or better XD-100 if my engine.

Cheers,

Huey.

[gregcrameri]

Hi, if the engine was only run for that short amount of time no mechanical damage would of occured and this can be confirmed by compression and leak down tests. I would drain the fuel, fill with premium fuel (from another place) and also drain the carby bowls. I also would make sure the fuel hoses, fittings etc are tight and do not let that engine suck air, I would make sure you are proped to see about 5500 at WOT and I would use as a min XD-50 in her or better XD-100 if my engine.

Cheers,

Huey.

Thanks Huey,

I really appeciate the advice.

Greg C

[jewgaffer]

Now that the winter has set in it is a good idea to maintain your outboard fuel by draining it after not using the boat for a few weeks and even then alternating your unused outboard fuel between the boat and the car. A fuel filter that separates the water from the fuel is a must own these days and it only pays to add a fuel preservative additive to each tank of new boat fuel icluding pre mix. As Huey wisely says it doesn't do any harm to use premimum petrol i.e. to revive the small amount of fuel that may remain in the tank. I believe that stale fuel whether contaminated or not is the number one killer of marine engines to the extent that it's not even worth flushing a boat motor or even running it under load to see how it runs as the components in the petrol may have already broken down and lost their effectiveness as far as the internal components having proper ignition and proper lubrication is concerned.

Cheers

jewgaffer