1994 Force 120 jerking or hesitating at any speed more frequently at higer speed

[leisalane]

Hi I am a first time poster but use this forum often to try and educate myself . I bought a 94 1700 capri ls Bayliner with a force 120 outboard back in Oct. So far with the help of my sisters neighbor have replaced the water pump the thermostat both carb gaskets the ignition and fuel filter because it was leaking . I put her in the water for the first time this season last week and when I put the throttle all the way forward pushed in the choke it started easily but I did notice it didn't rev up with in a min or so where I would need to back off into neutral . After a few min s I backed it into neutral and started out of my canal at idle speed actually a little faster then Idle because it seemed it was going to stall. I noticed the motor would jerk is the best way I can describe it but no bang or noise at all that I could hear, when I got out to the intercoastal I gave it a little more gas and still noticed the jerking not constant maybe every few min s. so I went to full speed and still felt the jerking but more frequently . I have done some reading and it seems it could be the shift cable or a slipping hub " but I didn't hear any rev " or a worn clutch dog and forward gear . I really hope its not the latter ... when I was letting it run while lid was off I did notice some gas dripping from bottom carb even though gaskets were replaced last oct. . and when I was running boat I did prime the bulb and it didn't make a difference in jerking. I cant do any work on my own YET : ) but just hope to be as informed as possible before taking boat to a mechanic I barely know . Sisters Neighbor not available : ( One last thing I did notice some slight stress to transform the top molding had a crack in it but could be normal wear .

Thanks ! any info would be great !!

Lady in distress ; )

 

[pnwboat]

Re: 1994 Force 120 jerking or hesitating at any speed more frequently at higer speed

If the motor is tilted down or close to being down in it's normal running position, you should not see any gas dripping from the carburetor.

Typically if the gas leak is from the carburetor itself, you either have a leak on the fuel bowl gasket(s), bad needle valve, debris stuck between needle valve and seat preventing the needle valve from sealing properly, or carburetor float is set too high and it's overfilling the fuel bowl and running out the fuel bowl vent hole.

As far as the jerking is concerned, it might help if you could post a video of it when it's acting up. Like you said, it may be a slipping clutch dog, or an ignition miss. Hard to tell from your description.

 

[leisalane]

Re: 1994 Force 120 jerking or hesitating at any speed more frequently at higer speed

Thanks ! I thought of posting video but you really cant hear it just feel it . My Sisters neighbor just text me back and he suggested draining the oil from lower unit to check for metal . so if metal free probably not the gear I hope , Yes motor was down and just dripping slightly out of carb but I guess this wouldnt have anything to do with the jerking ?

 

[pnwboat]

Re: 1994 Force 120 jerking or hesitating at any speed more frequently at higer speed

I kind of doubt that the dripping gas would have anything to do with the jerking but it's hard to tell without seeing it happen in person.

If it was a slipping clutch dog, I would expect to see the motor jerk each time it happened. It's a pretty severe event when the clutch dogs slip and then engage at any speed above idle. Checking the lower unit oil is probably a good idea.

Here is a video of a Force motor with slipping clutch dog. Not the best quality video and kind of short but you can see the motor jerk each time it happens.

85 hp Force outboard running wot - YouTube

 

[foodfisher]

Re: 1994 Force 120 jerking or hesitating at any speed more frequently at higer speed

Hopefully a spun hub. But it sounds like rounded corners on a dog/gear.

 

[leisalane]

Re: 1994 Force 120 jerking or hesitating at any speed more frequently at higer speed

I kind of doubt that the dripping gas would have anything to do with the jerking but it's hard to tell without seeing it happen in person.

If it was a slipping clutch dog, I would expect to see the motor jerk each time it happened. It's a pretty severe event when the clutch dogs slip and then engage at any speed above idle. Checking the lower unit oil is probably a good idea.

Here is a video of a Force motor with slipping clutch dog. Not the best quality video and kind of short but you can see the motor jerk each time it happens.

85 hp Force outboard running wot - YouTube

Yes I actually saw that and not the same as mine ,mine is less frequent and did not sound like that . im wondering if its the cable because when starting cold and throttle pushed all the way forward it didn't rev up like usual after a min or so ???? Ill check for metal tomorrow and go from there . Thank you so much for the info !!

 

[leisalane]

Re: 1994 Force 120 jerking or hesitating at any speed more frequently at higer speed

so I pulled the plug on lower unit and the oil just kind of dripped out and I let it drip on to a rag . I didn't open the vent maybe that's why it didn't pour out but what did come out didn't have any metal . Sisters neighbor doesn't think its gears since there is no grinding when shifting and no metal . He can look at it next weekend . He thinks its fuel related or ignition . I was thinking of putting new gas in there and star tron and running to see if there is any difference in the mean time . I will video the motor too to see if that shows something im not seeing !

 

[pnwboat]

Re: 1994 Force 120 jerking or hesitating at any speed more frequently at higer speed

Do a compression test to see what kind of shape the cylinders and rings are in.

Check the fuel pump diaphragm to make sure it's not torn or hard. Should be soft and flexible.

Take a look at the spark at the plugs. And maybe the plugs themselves. You should have a good snappy blue or light blue almost clear spark. Orange spark usually indicates weak spark.

With it running you should be able to touch the spark plug wires and not get shocked. Have someone you don't particularly care for try this test...LOL!

Make sure the wires that come out from under the flywheel from the stator and trigger have not rubbed and exposed the wire and are touching the engine. The trigger wires move as you move the throttle back and forth. Sometimes the flywheel will rub on the wires causing intermittent ignition problems.

Check all the ground wires. Each coil has a ground wire. There should be a ground wire that goes from the coil mounting plate to the engine block. This is a really important ground connection. Make sure it's making good contact.