Sudden loss of power and RPM's

[scooterdog]

All, I am just back from the river and I had a problem with my 1986 force outboard. I was cruising along at 35 mph and smacked into a line of waves. After about the third wave my engine suddenly lost power and would only go up to 2500 rpm with the throttle pegged. If the throttle wasn't fully pegged it was reduced to almost idle speed. I limped back to the dock at 8 mph and there it sits. When pulling into the dock the motor idled rough...it would rev then suddenly drop off and then rev back up but stayed running. It was storming when I got back and haven't had a chance to look at anything yet. I will be going to the dock in the morning (weather permitting) to check it out. Any suggestions on what to look at would be greatly appreciated. Thank you in advance!!d

​Scott

 

[Degrath]

Plug wire come loose from rocking in the waves? If they were all on tight pull one off at a time (with insulated pliers)while running to see if you notice a difference at an idle. If you pull one and it dies or gets rougher then its prolly ok. If you pull one and nothing happens then you might not have spark from that coil.

 

[kjprag01]

Bring Starter fluid and check for vacuum leaks. check the electrical connections, coming from the stator, trigger, coils. And on a very off the wall idea, maybe the prop nut/cone loosened up.

 

[kjprag01]

Check the prop for fowling, I just remembered when I was a kid, my dads boat had some similar issues once and there was some trash wrapped around the prop. We raised the trim to get the fly closer to our face and there was a few hundred yards of fishing line.

 

[jerryjerry05]

If you suggest using starting fluid to check for "leaks"
Then you should explain how to do it?????

​Using starting fluid can wipe the protective oil from the moving parts.

​To check for "leaks" your testing for vacuum leaks.
You spray the fluid at the bottom of the intake and on the seams of the block.
Any difference when you spray? then the seals gone bad and needs fixing.

​My self , I'd start with the ignition, the trigger leads are very thin and break or loose contact when jolted suddenly.
​The 86 had plug in connectors(bad) and they need to be taken apart and WD40 used or hook the wires direct.
​You have a kill switch? check the connectors.
Inspect the wiring harness and all connections.
Then check the fuel for water?
​Any filters in the system? If not add a water separating filter and a small particle filter between the carb and the pump.
​Fram G2 G-3 G-12 one of these works great.

 

[scooterdog]

Well...here's what I know so far. Compression is 125 on all cylinders. In line spark testers showed that all cylinders were getting spark. I took off the carb cover and all were parallel at WOT. I already have a water separating filter but..it is pretty old. I changed out the ignition switch and kill switch just before this happened (could this cause a problem??)

 

[scooterdog]

Oh..one other thing. When I remove the wire from the top plug it stalls out. The middle plug...no noticeable difference and the bottom it runs slightly slower. I have not tried changing out the plugs since they are new as well.

 

[jerryjerry05]

Well...here's what I know so far. Compression is 125 on all cylinders. In line spark testers showed that all cylinders were getting spark. I took off the carb cover and all were parallel at WOT. I already have a water separating filter but..it is pretty old. I changed out the ignition switch and kill switch just before this happened (could this cause a problem??)

​Yes the ignition switch or kill switch could have a loose connection or a bad wire?
You check the fuel in the water sep?

Change plugs around.
Take a pic of the end of the plugs.
They the right plugs??

 

[Nordin]

As there is no noticeable change in behavior when you move the middle hightension wire there is an issue at middle cylinder.

Check the thin wires at terminal board, the spring in the HT rubber boot coil 2, the HT wire coil 2 and the prime side wire to the coil 2.
Swap coil 2 with coil 1 and check if the issue moves to cylinder 1.

Since you says there are spark at all three cylinders checking with a inline spark tester it sounds like the spark is to weak at cyl.2 to jump in compression.

 

[scooterdog]

All,
​I replaced the #2 coil and still no change . One thing I did do...in an attempt to try something different, I sprayed seafoam into the intake. While I was spraying it the motor returned to a smooth idle (usually it bogs down when I do this). Carbs???

 

[jerryjerry05]

Clean the carbs.

 

[scooterdog]

FINAL UPDATE: Well..it was actually the bottom carb. It had fuel pouring out of the side of the bowl. I took it off and the gasket had broken apart and was all through the bowl and in the jets. Put on a replacement carb (will rebuild this one) and it took off!! Thank you to everyone for the advice!