90 hp outboard, loud ratcheting sounds just when I plane out, and then boat stalls

[cusson]

Help! 90 hp Merc, runs great at low speeds, just when I plane out, almost top speed,the drive makes a loud ratcheting or clicking sound ( sounds like the gears) and then the engine stalls. The first time it happened I thought I hit something. I thought I spun the hub, so I pulled it off and replaced with new prop, still same problem. Boat will run all day at low to mid speed, as soon as I give it some it happens.

 

[dcducks1]

Re: 90 hp outboard, loud ratcheting sounds just when I plane out, and then boat stall

Have you dropped the lower unit lately or disconnected/reconnected the shift cable recently? If the engine stalls out while its in gear it will make a clicking sound until the prop stops, but usually not before it stalls out. Does the rpm's increase when the clicking happens? My 90 used to bog down when I poured the coals to it and I rebuilt the fuel pump and the problem went away. Is their any kinks in the fuel line? This was also a problem that I found which would allow it to run at low to mid, but would starve the motor when trying for full power. Give us some more details of anything you have done ....or not done to it lately.

dc

 

[cusson]

Re: 90 hp outboard, loud ratcheting sounds just when I plane out, and then boat stall

Have you dropped the lower unit lately or disconnected/reconnected the shift cable recently? If the engine stalls out while its in gear it will make a clicking sound until the prop stops, but usually not before it stalls out. Does the rpm's increase when the clicking happens? My 90 used to bog down when I poured the coals to it and I rebuilt the fuel pump and the problem went away. Is their any kinks in the fuel line? This was also a problem that I found which would allow it to run at low to mid, but would starve the motor when trying for full power. Give us some more details of anything you have done ....or not done to it lately.

dc

I just replaced the ignition switch 30 minutes before it happened. Weeks earlier I replaced the trigger switch and re wired the boat and it's been running great since that. I also noticed when this happens, its starts hard after it stalls, and the battery is slow cranking at first then it kicks in and starts. Also a few weeks ago, the boat got swamped in a bad storm and sank on my dock. I had the boat out within a hour and running that night..not sure if that is related or not.

 

[cusson]

Re: 90 hp outboard, loud ratcheting sounds just when I plane out, and then boat stall

I just replaced the ignition switch 30 minutes before it happened. Weeks earlier I replaced the trigger switch and re wired the boat and it's been running great since that. I also noticed when this happens, its starts hard after it stalls, and the battery is slow cranking at first then it kicks in and starts. Also a few weeks ago, the boat got swamped in a bad storm and sank on my dock. I had the boat out within a hour and running that night..not sure if that is related or not.

Thanks for your reply, Haven't dropped the lower end or messed with the shifter cables. Rpms seem to bog as it happens, definitely no increase. also noticed the fuel ball keeps loosing pressure.

 

[dcducks1]

Re: 90 hp outboard, loud ratcheting sounds just when I plane out, and then boat stall

If you have a hole in a diapraph in the fuel pump it will bog down and lose pressure in the bulb. The kits are cheap and it is a very easy job if you take your time and take it apart slowly. Do you have any fuel leaks anywhere? It sounds as if it is sucking air somewhere? How do the plugs look? Have you checked lower unit oil to see if it has water in the fluid?

 

[Chris1956]

Re: 90 hp outboard, loud ratcheting sounds just when I plane out, and then boat stall

If the motor stalls at high speed, you will hear the prop ratchet. This is normal, and what I suspect is happening. Check the primer bulb. If it is soft, you have some restriction in the fuel line upstream of it, like a bad antisiphon valve or clogged tank vent. If the primer bulb is firm, then check your filters down stream of it.

 

[cusson]

Re: 90 hp outboard, loud ratcheting sounds just when I plane out, and then boat stall

Thanks for the replies! I checked the primer ball, it was soft... so I followed the line up to the engine and sure enough I found a large slit in the line. I primed the bulb and heard air, and saw fuel dripping. Parts store is closed now but Ill replace tomorrow and post the results. I never would have guessed fuel because of the ratcheting sound when stalling, I thought maybe the lower unit was bad... Thanks!

 

[cusson]

Re: 90 hp outboard, loud ratcheting sounds just when I plane out, and then boat stall

it was the fuel line, thank you!