V4 Johnson 90hp help

[Rebel]

98 Octane fuel is a much cleaner fuel. I have been using 98 Octane since day one, never had a problem.

Years ago I had a Hilux and the motor used to ping all the time. We tried everything to stop the problem.

I put 98 Octane in the tank, problem solved.

[noelm]

It doesn't matter how many years you have been using higher than recommenced octane in your Hilux, an outboard is kind of somewhat different, let me explain. On this particular carbureted outboard, the timing is manual advance, you move the throttle, the timing advances whether you like it or not (a car does not work this way) using the incorrect octane can induce long term failure, just like when your motor is over propped, you advance the throttle and timing (they are mechanically connected) but the over loaded motor (too big a prop, or wrong octane) has the timing set way advanced for the motors current RPM, firing way too early, continued use like this will create detonation, the piston is coming up, the advanced timing fires the fuel charge, trying to send the piston backwards while still on its upstroke, extreme heat can/will/does melt pistons, that's why it's essential your motor can achieve max recommended RPM, don't fool yourself into thinking a bigger prop will lower your cruise RPM, because you are doing damage to your motor. Cars, and EFI engines are a different kettle of fish. But that said, use what you like, it's your engine, but wasting dollars and abusing your motor doesn't seem like a big hit to me.

[Alex75]

1 hour ago, Rebel said:

Do a compression check on the motor. From memory it should be 120 to 130.

Also just to confuse you I use Nulon oil, just found it a better oil also always use 98 Octane fuel.

Have you got a water seperator on your fuel tank ?

Cheers.

I have a water separate on now. We did a compression test and 2  we're 125 one was 126 and one was 124.

[Alex75]

1 hour ago, antonywardle said:

+1 to having a water seperator.

I might have a manual for your ob if interested

 

PM me

You sent me one before, you helped me last time thanks mate. 

[Rebel]

Compression is ok. Keep the water seperator connected. Are the spark plugs ok ?

[Rebel]

After some research the Jury seems to be out on what type of octane fuel that can be used.

91 to 98 not EIO.

[XD351]

1 hour ago, Rebel said:

After some research the Jury seems to be out on what type of octane fuel that can be used.

91 to 98 not EIO.

Use what the manufacturer recommends or higher  octane .

Higher octane is less prone to detonation or pinging - never under any circumstances use anything with ethanol in it it is hydroscopic and you will end up with water in the fuel and it may damage some of the fuel system components like seals and hoses .

[Bryant fish]

That's the oil I've used for 25 years no problem but you still have the chance it won't mix with whatever oil you used before saying that if you dumped old fuel mix you should be ok 

[shakey55]

15 hours ago, Rebel said:

After some research the Jury seems to be out on what type of octane fuel that can be used.

91 to 98 not EIO.

I’ve a 2000 model Johnson 115hp V4 Oceanpro (2nd owner).  I have run 95 in this motor since I’ve had it and the original owner told me that he ran 95 in it since new.  Neither him nor I have had any fuel related issues using this fuel.  I can also say that since I’ve had the motor I have only used BP fuel, as I don’t go looking for somewhere to save a cent or two.

The Evinrude site says use 87 or 89 octane fuel, but the USA fuel rating are taken from AKI which is the average of RON & MON indexes.  Now getting technical, but the American 89 octane is, I think somewhere between Australian 95 & 91.  So once again it’s your choice  

Use what you want but find one that you are happy with and stick to it.  Same goes for oil, find a TC-W3 rated brand that you believe works for you and stick with it.

It really is a personal choice and what works for and is readily available to you

Good Luck

[frankS]

I use Valvoline in my Mercury, Johnson, Yamaha , Tohatsu motors and have done for years no problems.

Of course I use XD 100 in my Evenrude ETecs.

Frank

[noelm]

I am pretty sure there is no bad oil, for decades I used Shell Nautilus, (because I could get a 20l drum for peanuts) others said it was rubbish, just use what's readily available, and unless it creates an obvious problem (though I don't know what problems it can create) just stay with it. On motors with an oil tank (not a mix your own) adding a different brand can cause drama, for some odd reason, some oils, when mixed, cause almost like mud balls (for the want of a better description) in the tank, I once asked my local oil depot about this, and was told it's very common when two stroke oils are mixed with other brands (not all of them do this) I haven't had a two stroke outboard for a long time now, so I don't know if this issue still exists

[Alex75]

Right side top spark plug was oily and on the left side it was the same but not to bad. 

[Smobaby]

Looks like you have a problem the lower right plug has no residue at all. Your motor is running on 3 cylinders they should all be looking the same. Is that cylinder sparking the plug even looks dry is the compression even in that cylinder compared to the rest. In a 2stroke at idle and lower RPMS the plugs will be oil fouled in a premix engine the only way to check the plug colour would be to run at WOT then pull the plugs and check the colour. The only external adjustment you can do is the idle mixture 0 to 1/8 throttle. After that the jets takeover. Give it a good water test (flogging) then recheck the plugs, burn all that unburnt oil out of the system. Might need to service the carburettors.

[noelm]

Yep, one plug is a) washed clean with water, b)no fuel at all (means no oil too in your case) c) no compression on that cylinder you need a bit more investigation before running at full throttle.

[XD351]

I would check that there is spark at that clean plug first , it might be a dead plug from new or a coil has died  . If that cylinder has no ignition it is acting like a pump blowing air fuel mix out into the exhaust . Your compression is ok  for an old motor and doesn’t show any real difference between cylinders . If that clean plug is from the lowest cylinder ( I think bottom left cylinder is the lowest ) it could have a blown crank seal and it could be blowing the crank gases out into the leg as the piston compresses them . 

 

[zmk1962]

Another test you can try is to swap the plugs around. Put the lower left clean plug into another cyl and run the motor. If it comes out like the other 3 now you know that plug is working and your issue is with the lower left cyl, it’s fuel/oil supply or electricals (coil, cable etc). 

Edited August 6, 2021 by zmk1962

[Alex75]

31 minutes ago, zmk1962 said:

Another test you can try is to swap the plugs around. Put the lower left clean plug into another cyl and run the motor. If it comes out like the other 3 now you know that plug is working and your issue is with the lower left cyl, it’s fuel/oil supply or electricals (coil, cable etc). 

Thank you I will try that tomorrow. 
 

thanks to all you guys for all your help 👍🏽

[Bryant fish]

Take the plugs out and keeping leads on turn motor over you should be able to see a spark and while it's nothing on a proper car by rebuild get a can of carburetor cleaner and give it a good spray 

[Bryant fish]

Hey Alex did you get it sorted