Another problem with 1975 Johnson 85 hp v-4

[MotoBoat]

First off, thanks to those helping diagnose my " motor does not start issue". Replacing a 6 AWG battery cable solved that issue.

Before that no start issue I had been diagnosing why #4 cylinder does not fire.

Four fresh Champion QL77JC4 spark plugs in motor.

#4 spark plug has spark when grounding to outboard block.

A couple things. After running motor, All spark plugs are really wet with fuel. Is this normal for a motor this old? Did these motors waste that much fuel when running?

With #4 spark plug removed and motor running I placed a 12" x 12" piece of cardboard in front of empty spark plug hole to catch the spray that come out. Smells like fuel. I poured a drop or two that was on plug onto that cardboard and lit it with a bic lighter. Barely burned. By that I mean it took some doing to get a flame started, is this common with 2 stroke gasoline?

Secondly, with engine running I took a flame to that liquid spurting out of #4 cylinder expecting to see fire balls. Nope, substance did not ignite.

Tonight, I am going to swap #2 and #4 coil wires at power pack, and swap spark plug wires to verify if #4 coil is working properly. And if #2 will fire in #4 cylinder.

Am I dealing with a carburetor that is flooding #3 and #4 cylinders? #3 spark plug is firing, but color wise, it is much lighter than #1 and #2 spark plugs give same few minutes of run time they have on them.

Or, is this a head gasket issue? How would I check for a bad head gasket? I could start the engine with no water running, quickly pull #4 plug wire from cylinder but I don't want to eat up a impeller doing so.

Last time I checked all cylinders had compression between 116 - 126 psi. #4 had 116 psi. I do need to re-test since last checking was some time ago.

 

[oldboat1]

Put away the Bic lighter!! Fuel ratio is 50:1 (2 1/2 - 3 oz. per gallon -- 2.56). Possible you have water in the fuel.

Use an adjustable spark tester, open air variety:

 

[F_R]

By carelessness, I dang near set myself and the whole shop afire when I allowed a spark tester to be in line with a spark plug hole. As you expected, fire came shooting out that hole like a flame thrower. (engine was flooded).

Can't be too careful when messing with this stuff.

 

[MotoBoat]

Oldboat1, I do not have a spark gap tester that is where a thought to swap coils came from. As far as water in the fuel, how would 3 cylinders be running normally given 2 carbs supply 4 cylinders?

 

[oldboat1]

Auto parts store for an adjustable, open air start tester (cheap). Would just check the fuel (sample some from the bottom of the tank and let it settle in a glass jar -- fuel will float on top of any water.)

 

[MotoBoat]

F_R, okay no flames around Outboards. So, my thought was that #4 cylinder was flooding. But consider #3 and #4 cylinders are fed by same carb, how likely is it that #3 is firing with water in gas while #4 is not?

I get where oldboat1 is going. Check spark gap at #4 spark plug..........check for water in gas. I am thinking "yes" there is water in the gas, but not coming from fuel tank (motor running on 3 of 4 cylinders. One of running cylinders gets fuel supply from same carb) but instead a head gasket.

 

[racerone]

Each carburetor bore feeds just one cylinder.----You could have leaks that allow water into the motor.

 

[MotoBoat]

Okay, makes sense since there are 4 bores. Is there one or two floats per carburetor? Looking at carb schematics for rebuild kits it looks like one per carb? 2 carbs in total for my motor?

oldboat1, at what distance should gap tester be set?

 

[oldboat1]

Upper and lower carb, one float each. Should have a parts diagram and kits here at iBoats.

Believe you should expect 7/16 spark on that motor. I would set it for about a half inch, and dial back until I saw a strong spark. Make sure you have a good ground for the tester (may need to use a jumper) -- keep spark away from open plug holes (test with all plugs removed).