Johnson VRO 70 HP, stops at low speeds

[Barryvillegas]

My engine runs really fine, but when idle (very low speeds) it stops and sometimes it doesnt starts again for a minutes!! Someone told me that maybe its a lost of compression in one of the pistons!!what can be the problem????!!

 

[DHPMARINE]

Re: Johnson VRO 70 HP, stops at low speeds

Next time it tries to stop,try squeezing the primer bulb.If the engine recovers each time,probably time for a new VRO/Fuel pump.<br /><br />DHP

 

[Barryvillegas]

Re: Johnson VRO 70 HP, stops at low speeds

I tried it, and it dont solve the problem. Thanks for help, i expect further replies!!

 

[OBJ]

Re: Johnson VRO 70 HP, stops at low speeds

Hello Barry and welcome to iboats!<br /><br />You said in your original post that "sometimes it stops". Does that mean that sometimes it will idle well and it will stop at other times? If so, you may be due for a carb overhaul. Could be some junk floating around in the carb bowls. Or it could be just a sync and link problem. <br /><br />Before we start tearing things apart, let's get a compression test on all the cylinders and a spark test to make sure that much is OK. Then we can go from there. Any other thing you may have tried would be helpful also. And could you post the year or model number please?<br /><br />Do you have a service manual? If not, this would be a good time to get one. Would help in the troubleshooting and general maint of the engine.<br /><br />Keep us posted.....thanks.

 

[Barryvillegas]

Re: Johnson VRO 70 HP, stops at low speeds

Thanks for help!!<br /><br />What i wanted to said its that sometimes the engine doesnt start again after it stoped,the engine always stops at idle. Can i do the compression test by myself? what tools do i need? The outboard its a 1989 Johnson VRO 70HP and it was not running for 7 years!!!! The engine runs really well and this is teh only problem!!<br /><br />Keep me posted....thanks

 

[OBJ]

Re: Johnson VRO 70 HP, stops at low speeds

Yes you can do the compression test your self. Just need a screw in type compression test gauge. If the engine has set for so long, I would suspect that the idle jets are plugged with varnish. I would strongly recommend a complete carb overhaul. Would probably make all the difference. <br /><br />You can also easily check the spark. Cut the head of a large nail off and stick it in the number one spark plug wire. With insulated pliers, hold the point of the nail 7/16 to 1/2" from a clean engine ground and have someone crank the engine. You should get a strong thick hot white spark in the gap. Do this to all spark plug leads. If they are all good, ignition system is working OK.

 

[Barryvillegas]

Re: Johnson VRO 70 HP, stops at low speeds

What pressure ranges should the test gauge register for each piston?. Will i put the the test gauge where the spark are connected (obviously without the spark)??

 

[OBJ]

Re: Johnson VRO 70 HP, stops at low speeds

Basically when doing compression test, the higher the readings the better. But more important is the relationship of each compression reading to the other. All reading should be within 10 to 15% of each other. So, just grabbing some numbers, if all cylinders read between 90 and 100psi, you should be OK. But for instance if you have a cylinder that reads 80 as compared to 95psi, there could be a problem. What is generally suggested in a case like this would be to do a decarb and then run the test again. If the engine is new to you, it would probably be a good idea to do a decarb any way.<br /><br />Yes, you remove the spark plugs to so you can screw in the gauge.

 

[Barryvillegas]

Re: Johnson VRO 70 HP, stops at low speeds

When you said "Carb" you refer to carburetor isn´t it? And when you said "decarb" you refer to removing carbon from pistons? Before the explanation of this , tell me please who do i do a decarb? Excuse me if sometimes i made ridiculous questions, i am new on this and i am spanish speaking.<br />i really appreciate your advices and help.

 

[OBJ]

Re: Johnson VRO 70 HP, stops at low speeds

Barry, one thing there is not on these forums is ridiculous questions. So ask away if ya' don't know.<br /><br />A decarb is a simple thing to do. There are several brands of "decarb" agent, Bombardier, SeaFoam, etc....and all use about the same process. You put the muffs on the engine, run it till it's up to temp and start shooting the agent down the throats of the carbs or in your case, look at the engine and locate the primer solenoid. Should be on the starboard side of the engine and have a little red lever on it. If it has a Shrader valve on it your in luck. John/Rude dealers sell engine tuner in a can that has a matching connection that you can screw onto the Shrader vlv. then you just push the button on the can to inject the engine tuner. Anyways, either way, you need to get the decarb agent into the engine either through the carb or the primer solenoid while the engine is running. Once you have got the whole can in (read the directions on the can cause some brands vary in use) you shut down and let it set for how ever long the directions say. Start her back up to burn out the rest. If the carbon ain't to bad and you do this often, you shouldn't have problems with carbon build up.<br /><br />Yeah, "carb" is short for carburator...don't even know if I spelt it right... <br /><br />Have you maybe decided on getting a Service manual?? Would tell you a lot and you would have it in front of you anytime you needed the info.<br /><br />Man! this was a long winded post....

 

[Barryvillegas]

Re: Johnson VRO 70 HP, stops at low speeds

Thanks a lot for help, your advices will be useful, i will search teh "decarb" agent here in mexico, i suppose i can find it not only in boating related stores. if not i will try to find an internet international shipping store. Thanks, thanks a lot for your help!!!!! <br /><br />------------------<br />* When all else fails..... ask OBJ.

 

[fireman57]

Re: Johnson VRO 70 HP, stops at low speeds

Just a warning. When you decarb this engine get ready for a lot and I mean a whole lot of blue smoke. If you can do this where there are not a lot of people around it would be a good idea. If you can do this in a lake with no one around they might not call the fire department. Do not do this in a garage as you won't be able to see or breathe.

 

[Barryvillegas]

Re: Johnson VRO 70 HP, stops at low speeds

Another question!!! <br /><br />I want to disconnect the VRO pump and run a premix but i have a question!! If i use my outboard 80% for trolling (almost idle speeds) and 20% other stuff, am i taking a good decision? The premix is 50 fuel-1 oil? the ratio changes for trolling?? Can i reconnect a VRO pump when i have new one?