Gonna repower my 1988 GW Overnighter with a Yamaha 150 four stroke. I'm changing over from an old Mercury 2 Stroke. I've been manually mixing my outboard oil and gas. The old engine is dead and the tank is nearly full. What should I do with the old tank of gas/oil mixture? Second, when clearing the gas tank is there a vaccuum device that can remove sediment or particulates from the bottom of the tank to prevent any clogging of the new motor? Thanx for any advice. Neil
2 stroke to 4 stroke conversion.
- Thread starter McG
- Start date
See if you can give it away to a fuel dock that sells pre-mix if any exist any more. Research "fuel polishing" in your area. Short of pulling your tank, that's probably the best you're going to be able to do to clean the tank. Make sure you have a good external fuel filter rigged up before your run your new motor.
I think I'd just remove about half the fuel and fill it back up with straight fuel so you'd have a mixture that would only be about 100:1 and I don't think it would hurt your new 4 stroke a bit, but ask your Yamaha dealer if you want to be sure. Then, as your tank gets empty, gradually burn the mixed fuel you removed. As for protecting your engine, if you haven't been having fuel trouble with your old 2 stroke, you don't need to worry about your new motor either. I'd add an inline, water separating, fuel filter before you run your new engine, but other than that, I don't think you need to worry at all.
If you don't have an easy way to remove the old fuel, just take the mercury fitting off the end of the fuel hose to your old engine, set a 5 gallon tank on the ground behind your boat, and squeeze the bulb as if you were priming your engine. With the end of the hose as low as possible below your fuel tank, as the fuel starts to flow, it'll keep flowing until you raise it higher than the boats fuel tank.
If you don't have an easy way to remove the old fuel, just take the mercury fitting off the end of the fuel hose to your old engine, set a 5 gallon tank on the ground behind your boat, and squeeze the bulb as if you were priming your engine. With the end of the hose as low as possible below your fuel tank, as the fuel starts to flow, it'll keep flowing until you raise it higher than the boats fuel tank.
Neil, If I may offer a suggestion. Go to your local auto parts store and purchase an inexpensive electric fuel pump. Mount the pump on a board with hose on either end and powered by an auto battery, you can drain your tank. Remove the sending unit and you can get the suction hose to the lowest portions of your tank and get all the "junk" out. After that, reseal the sending unit and install a 10 micron filter/water seperator. I'm guessing your dealer would insist on this to ensure warranty coverage on the new motor. Good Luck and tight lines.
Never, ever, under any circumstances try and run a four stroke on fuel that has been contaminated with two stroke oil. Oil reduces the octane rating significantly. The F150 four stroke is a high compression motor and does not have a knock sensor. High compression motors don't last too long with fuel that has insufficient octane. Can you say detonation? Can you say holes in the top of some pistons?
2 to 4 stroke conversion
Just replaced my old 2 stroke with a new F250. My dealer insisted that he pump out the old gas and clean the tank. With the amount of money you pay for a new 4 stroke you don't want to take a chance on damaging it with bad fuel or any trash that may be in the tank. He also said that the warranty may not cover any problem that would be considered fuel related.
Just replaced my old 2 stroke with a new F250. My dealer insisted that he pump out the old gas and clean the tank. With the amount of money you pay for a new 4 stroke you don't want to take a chance on damaging it with bad fuel or any trash that may be in the tank. He also said that the warranty may not cover any problem that would be considered fuel related.
weir mako21
New Member
If the gas is still fresh, find another guy who pre-mixes and give him a $240 present. Remove old fuel line after the primer bulb and attach a length of extra hose. Pump the bulb to start a siphon into jerry cans (as low as possible below the hull. Let gravity drain the tank. Just did mine like that when I pulled my tank.
-John
-John
gradyfish22
GreatGrady Captain
You have 2 options, either have a yard remove the fuel, they are more suited for this job and many have tanks that can handle the removed fuel, to do this yourself and contain that much fuel is a big job unless your really meticulous and handy. If you do it yourself...fill smaller gas cans and run the gas in your car!! I would highly advise against running any of that fuel in a brand new 4 stroke....the first hours of a 4 stroke engines life are cruicial, running oil through it during break in could really harm the engine or reduce its longevity. I would not take any chances with a brand new engine. Your other option is to hire someone who can polish your fuel, this is the more typical way. It keeps everything out of your hands, and it typically costs less or the same as buying a new tank of gas, but you do not need to remove the old fuel yourself nor store it nor clean it. Fuel polishers are highly used worldwide and very successful. Large sportfishermen who fish over seas of in exotic ports often have fuel polishing systems onboard just to clean and purify there fuel from a port where fuel might have sat a long time or where fuel storage is not regulated very well.
Personally I would go with having the fuel polished, it takes liability out of your hands and places it with the company performing the task, its also highly effective and will leave you with a full tank in a quick amount of time and the least bit of hassle to do so. Whether you remove the gas and refill the tank or have it polished, it will cost roughly the same to refill the tank or have it polished so going the easier route just makes more sense.
Personally I would go with having the fuel polished, it takes liability out of your hands and places it with the company performing the task, its also highly effective and will leave you with a full tank in a quick amount of time and the least bit of hassle to do so. Whether you remove the gas and refill the tank or have it polished, it will cost roughly the same to refill the tank or have it polished so going the easier route just makes more sense.
Doc Stressor
Well-Known Member
Fuel polishing won't remove the 2-stroke oil. You'll have to sell or give away that tank of fuel.
I agree that running poor fuel or fuel containing 2-stroke oil during the beak in period is a bad idea. You don't want deposits forming as you try to seat the rings.
I agree that running poor fuel or fuel containing 2-stroke oil during the beak in period is a bad idea. You don't want deposits forming as you try to seat the rings.
Just replaced a tank on a 1988 grady...was developing pin holes and leaking into the bilge...If you have a 1988 grady your tank is probably due for a new one...I would not want to replace my new motor only to develop problems with rust particles...Gas related ISSUES ARE NOT COVERED BY WARRANTY....do I need to say that part again?....Look at the SMELL OF GAS thread under general discussion.