Johnson 70hp VRO just lost power and cut out

[Revhob]

I have recently bought a boat with a Johnson 70hp VRO. The previous owner showed me it running and assured me it was a good runner. Other than having a boat in my late teens, I have no experience, just leaning again. Started lovely and was in our first trip out cruising across the bay. The engine then started to slow down till it stopped and cut out. I turned it over but it turned very slowly and didn't start. I tried again and it whizzed back to life. We started to head back in and the engine began to slow up and die. This time, when trying to start it, it turned slowly again but failed to spring back to life. I also attached a spare battery via jump leads, but this made no difference. We were then towed back into the harbour by another boat. I may also just mention, the tweet sound when turning the key tweets ever so often when engine was running. Would appreciate your advice if you can help Cheers Paul

 

[racerone]

Do a compression test.----------------Is oil injection in service and operating properly ???--------Was it bypassed and do you need to mix gas and oil at 50:1 on it ??------The warning horn may be for overheating.---Do you have an owners manual and did you read it ??

 

[glenn property of pam]

You don't mention the year but I would presume that the engine has a tell-tale on the back right corner of the motor. When the engine is running a stream of water should be coming out of that hole. On the 70 the stream so be strong and straight. This is a visual signal that the motor is getting enough water to cool the block.
On a unknown motor its best to add oil to the gas at about 80 to 1 mix then mark the oil tank level with a pen. If the level in the oil tank stays the same then you have a oiling problem. If the level drops then the oil system is working so you will no longer add any oil to the gas. The oil that was added will not hurt other than to smoke a bit and maybe foul a plug until its used.
Do you know that pushing the key in chokes the engine, The fuel bulb should remain firm when you pump it before starting, The fuel bulb should not collapse when the engine is running, The fuel addition solenoid has to be in auto (choke) the red lever is in line with the body, Battery cables have to be clean and tight.

 

[Revhob]

Just to mention, before I begin to get my hands dirty. The fly wheel is turning freely by hand, but when turning the key the starter motor in turning slowly and intermittently. I will do as you have suggested with the oil when I can get it running again.

 

[glenn property of pam]

sounds like you need to clean all the large terminals on the main cables. Remove the cables one at a time and clean the ends. This also includes the negative cable and the area on the block it bolts to.

 

[Davee3]

My 1992 60HP seized when alarm did not work & VRO probably failed. You need to bypass it to be safe & mix oil/gas If same vintage cooling need a rework telltale for water needs to come off the top of the engine as the low connection leaves air pockets I seized two of 3 cylinders / Yours sounds like voltage/amps do not get to the starter - Does the solenoid on the starter Click striongly when key turned

 

[Revhob]

Just to update you, it turns out the battery was dead, not just drained but dead. I have replaced this and cleaned and tightened all the terminals. Is it normal for the engine to lose power and then shut down when the battery is dead? Also the warning tweet is still sounding every 30 seconds or so, even when engine is cold, what could this be? cheers Paul

 

[racerone]

That motor will run forever with a dead battery.------The battery is used to crank it over for starting.---The ignition system work off a spinning magneto and not by 12 volts from the battery.

 

[Revhob]

Thanks to you all for your help, I have just returned from a whole day of successful boating. I replaced the Battery and cleaned and check all the connections. I also replaced the oil in the tank and marked the tank as suggested above. I also added 2 stroke oil to the fuel as a precaution. On arriving back I checked the oil in the tank which had used the prescribed amount for the amount of fuel. VRO still working! All I had to do was clean the sparks every now again while out as they were causing it to start badly after a while of running. I intend to do a service now, so thanks again for all your support, Paul