Evinrude 120hp V4 problem

Engine is cutting out at higher engine speeds What could be the problem? Ignition or fuel related?

[@clayfromthearth]

My 93' johnson 120 is doing the exact same thing right now! 🤯

[@dollbagius]

It turned out to be the CDI unit. I changed it this winter and now the problem is gone.😀

[@Dr.Juerdotitsgo]

I have a 94’ Johnson 120 v4. I leave the boat on a lift in the water. Unfortunately, the bilge pump burnt out while I was away for a week and the cover ripped and filled the boat with a bunch of water. Consequently the gas tank was compromised with water and the motor would just bog out. I hooked up an external tank and it ran great. After pumping the water/gas from the original gas tank and using some heat mixed with new gas it ran for about 5 minutes then went back to bogging hard. Turned out to be the fuel pump. It must have sucked up some sediment and destroyed the diaphragm. HOWEVER, the issue presented in this video seems to maybe be spark related, as it seems the engine is turning on and off as if a plug cap or something dumb is not making good contact. Obviously check fuel and fuel pump…perhaps a main jet is clogged on 1 or more carburetors. But I wouldn’t look past ignition issues. Not sure if he has solved it yet but just throwing some of my personal encounters with these engines. Best of luck 😎

[@prikbastrd]

Are you in any of the Evinrude and Johnson facebook groups? I got tons of good advice in there.

[@johnnypreskitt2952]

My brother had a yamaha 90hp doing the same thing. It was not getting enough fuel. Check your lines and filter.

[@fvgc454ss]

What was the the problem

[@dollbagius]

The CDI unit was faulty..

[@razor56p]

@@dollbagius i just bought 1985 120 apparantly not running right. Changed fuel pump from dead 90hp. It ran then died after 2 mins. CDI off 90 was same so changed it out and runs like a champ. Not bad for $500 motor. What plugs are you running?

[@dollbagius]

@@razor56p $500 seems like a bargain. I use Champion QL78YC plugs.

[@fleetwin1]

OK, well the video is a little garbled, so hard to pinpoint it....But, it sure sounds like an ignition miss. I don't think the engine is in "SLOW" mode though. Sometimes gearcase issues can create this type of banging around. What type of prop are you using, you might want to change the gear lube as well... Keep in mind it could be something as simple as a bum spark plug....Just cuz the plugs are new doesn't mean they are any good. This engine must use the champion "Q" plugs, or RFI interference could result. Seems like it runs OK up to about 3/4 throttle, then starts breaking up when you push the throttle wide open... The first place to start is with simple things....Stop/key switch elimination test, then checking all grounds and amphenol/coil primary connections...Sometimes the cover latches get caught on the plug wires ripping them partially off or grounding them also. Has anyone messed around with any of the sync adjustments, perhaps they are off.... Please just don't start replacing expensive ignition parts without adequate testing revealing an actual problem...These parts are very expensive, not so easy to replace, and usually are not returnable... Many issues are simple ones, never skip over the basics....

[@dollbagius]

@kramden Thank you for your answer! I was also into that the problem has to be ignition related rather than fuel related. When I filmed this I had already changed the spark plugs (champion QL78YC) but the problem remained so that is already ruled out. In the film I'm also running it with a portable fueltank just to make sure that the fuel in the main tank was not contaminated. I have inspected all coils for cracks and all cables seems to be OK. I have not touched the sync adjustment so I don't think that can be the problem. The prop is an ordinary alu and i think its an original OMC one. I change the oil in the gearcase once a year. What I have done now was that I bought a cheap electric fuel pump and by-passed the VRO pump. That seemed to solve the problem. I have not been able to get the problem back again and I have really tried to provoke it. I have disassembled the VRO pump and inspected it but everything seems to be OK. The diaphragms was without cracks and everything was clean. What I will do now is to connect the VRO pump again and see if the problem comes back. If it does come back I will buy a new fuelpump but not a VRO one because they are very expensive. If the problem doesn't come back it must be an intermittent fault and then I don't know how to further. It will be hard to troubleshoot so I guess I have to wait until it shows up again. Then I guess I will check the stop switch and its wiring as you suggest.

[@dollbagius]

I changed the CDI unit and that solved the problem.😃

[@fleetwin1]

@@dollbagius Cool, glad it worked out OK