Premix vs oil injection

[danie]

Hi all<br />I have a 1988 Mariner 90 3 cyl outboard with oil injection used for skiing/cruising (50/50) about 20 hours a year. The low oil warning unit in the oil tank went south and I cant find a replacement anywhere. Remember Im in darkest Africa and boating is a small business here, (anyone has an oil tank with working unit for sale??).<br />Im thinking of changing to premix for peace of mind but I am told that my motor runs at 50:1 and idles at appr 80:1 or leaner (wish I could get the right info).<br />My question is: Will my motor thats given trouble free service for so many years at whatever the oil injection feeds it, become clogged when suddenly forced to run on 50:1 from start to finish?<br />We dont have Seafoam here and to decoke with Power Tune ..... well, to decoke is a pita. Even trying to remove the plastic cover from the front of the carbs is an effort. And getting fined for air pollution, no thanks. <br />I use Shell Nautilus oil with surface gap plugs and the motor is very clean and in top condition.<br />Sorry for the stupid question but if I could fix the float/magnet/tank or lay my hands on a new tank all this would not be necessary.<br />Im all ears.<br />D

 

[Chris1956]

Re: Premix vs oil injection

Damden, In Premix motors the gas/oil ratio (usually 50::1) is specified for full throttle operation. If you were only to use a premix motor ONLY at idle speed, you could mix the the gas/oil at a higher ratio (say 80::1). <br /><br />The oil injection feature of your motor varies the gas/oil mix in this way. If you are idleing, it senses this and adds the appropriate amount of oil, and as you accelerate, it adds more oil to bring the mixture to about 50::1 at full throttle.

 

[rayjay]

Re: Premix vs oil injection

At only 20 hours a year you will never know the difference plus premix gas does not go stale as fast as straight gas. <br /><br />Plan B. Check the oil tank before every use.

 

[DJ]

Re: Premix vs oil injection

Damden, In Premix motors the gas/oil ratio (usually 50::1) is specified for full throttle operation. If you were only to use a premix motor ONLY at idle speed, you could mix the the gas/oil at a higher ratio (say 80::1). <br />

"Many" oil injection systems today do not alter mix ratios. It's just too risky-for the "general" public.<br /><br />True, 50:1 is ideal for WOT operation. However, leaner ratios have worked well too, with other issues.<br /><br />The leaner ratios are no longer rercommended due to corrosion resistance while NOT running.<br /><br />An "in tune" engine should idle all day with 50:1 with NO issues.<br /><br />The key is: "IN TUNE".

 

[dajohnson53]

Re: Premix vs oil injection

First, it is very common to disable oil injection systems and pre-mix instead, and there are no problems that I've ever heard of doing that. If that's what you want to do, do it and don't worry about it.<br /><br />Second,the only "POSSIBLE" problem would be at extended idling (and even that is mitigated by speeding up every once in a while or just checking, cleaning or replacing plugs every once in a while - NBD. I don't see extended idling as part of your 50/50 mix. <br /><br />If I were presented with a situation like yours - difficult or expensive to repair oil injection system - I'd disconnect and premix.

 

[north40]

Re: Premix vs oil injection

iShopMarine.com has tank listed for about $29 USD. I think they would ship to you but you would need to check with them. Used tanks are unreliable at least in my personal experience.....I tried 2 when mine quit working and finally gave up and bought a new one. I tried everything to get the float inside to work again without sucess. I think they get a wax buildup from the oil over time or something and won't "float" anymore.

 

[Moody Blue]

Re: Premix vs oil injection

Why "fix" something if it isn't broken ? If the injection system is working reliably but the low oil alarm is broken then just check the oil level frequently. When you fill up on gas check the oil just like you should with your car or truck. If it is below 1/2, fill it up.

 

[danie]

Re: Premix vs oil injection

Thanks everyone for the comments and recommendations.<br />I cant affort huge repair bills for a list of broken things at a time so I have to get something fixed the moment it breaks.<br />So thank you north40, I will try and get the oil tank as mentioned and yes, I will check the oil level as usual and go to premix as a last option.<br />Thanks again<br />D