1986 force 85 hp no power at WOT

[emirikol0113]

Hello guys,
I took my boat out today and the engine ran great for about an hour. After that it would not plane out. It seemed like the engine was bogging down. It idle's fine and starts faithfully. It will start to throttle up but at 3/4 to WOT it loses power. My boat usually runs at about 38-42 mph and I could not get it over 22 mph. I have verified that it is pumping water, it has spark on all three cylinders, plugs are brand new, I also tried a different fuel tank and same thing, vents are not plugged on either tank, the primer bulb apears to be ok it wasn't colapsed or empty. I have checked all fuel lines and nothing is leaking. I did do a little idling today but nothing to extensive. I brought it home and put muffs on it and I ran it. It seemed to start clear itself up like it was carboned up or something but I could never get the response I am used to out of the engine. I also tried to compress the priming bulb will my wife was driving to see if it was a fuel pressure issue and nothing changed.

 

[pnwboat]

Re: 1986 force 85 hp no power at WOT

Looks like you've covered most of the basics. I would try a compression check. If that is OK then then I'd double check the spark. It's sometimes hard to determine if the spark is adequate. The CD modules are notorious for weak spark. What I do is run the motor at an idle. Pull one spark plug wire off at a time. Motor should decrease in idle speed each time you pull a wire. If you have a wire that has no affect on idle speed then I'd start looking at that particular cylinder. Check stator windings, ignition ground connections etc. Swap coils and see if the problem moves. If no change then swap the modules to see if the problem moves.

 

[foodfisher]

Re: 1986 force 85 hp no power at WOT

Also check the fuel pump diaphram.

 

[Mark9740]

Re: 1986 force 85 hp no power at WOT

Agree with foodfisher. Mine had a tiny almost undetectable hole in the fuel pump diaphram. It would flood the bottom cylinder at WOT and bog down my engine. Took me forever to figure it out.

 

[emirikol0113]

Re: 1986 force 85 hp no power at WOT

I performed a compression test and I am getting 138psi in #1, 142psi in #2, and 137psi in #3, I checked spark and all cylinders are getting good spark they all change the idle speed when the wire is removed. I have disssembled the fuel pump to check the diaphram and it is ok.I even went as far to check it with a magnifying glass. I also pulled all the bowls down on the carbs to check for debris in the bowls I found nothing. I just replaced the NGK plugs with a Champion plug #L20v because that is what the engine called for is it possible that the plugs fouled after 1 time out in the water. Should I stay away from Champion and go back to NGK? Also should I use a hotter plug? If so what plug do you guys recommend? Also should I be using regular, mid-grade or premium gas for this engine. It seems like everyone you ask has a different opinion. Thank you guys for the input so far it is much appreciated.

 

[Frank Acampora]

Re: 1986 force 85 hp no power at WOT

Champion or NGK--It doesn't matter. Stay with the correct heat range, don't go hotter. At 9 to 1 compression ratio, regular 87 octane pump gas is the fuel to use.

Now, you can go crazy and check ignition and everything else, or you can listen to your engine. It is telling you that it is running out of gas over 3/4 throttle. This means a partial clog somewhere, sticking valves in the primer bulb, too low a carb float level, clogged high speed jets, bad button valves in the fuel pump, inlet needle seats swelled partially closed, pulse hole and/or pulse hose clogged, etc.

Start at the tanks and check the complete fuel system starting with the most likely (partial clog) and progressing to the most complex and least likely. Do pay attention to the quick-connect fittings and don't forget to check the screen behind the black inlet cover.

Last week I was checking a prop. After I switched tanks, the engine started to run like crap and would run out of fuel after only a couple of seconds at full throttle. It is difficult to diagnose a problem out on the water. So I went home. After arriving home I drained and checked the tank. Somehow, some leaves got in and were sporadically clogging the pick-up. Couldn't see them until the tank was drained. MORAL: Check your complete fuel system even if you think a component is OK.

 

[cbercaw]

Re: 1986 force 85 hp no power at WOT

Wont you get shocked if you touch the boot while it is running?

Looks like you've covered most of the basics. I would try a compression check. If that is OK then then I'd double check the spark. It's sometimes hard to determine if the spark is adequate. The CD modules are notorious for weak spark. What I do is run the motor at an idle. Pull one spark plug wire off at a time. Motor should decrease in idle speed each time you pull a wire. If you have a wire that has no affect on idle speed then I'd start looking at that particular cylinder. Check stator windings, ignition ground connections etc. Swap coils and see if the problem moves. If no change then swap the modules to see if the problem moves.

 

[emirikol0113]

Re: 1986 force 85 hp no power at WOT

I did get shocked pulling all 3 boots on the spark plug wires even with insulated pliers. I believed it was running out of fuel too. I remove the quick disconnect and installed on the end of my fuel hose and put it in side the tank and ran the engine still the same results. If it was running lean would it smoke like crazy at WOT? Also after I run it the plugs are wet. I thought a float was stuck or gas had penetrated the float causing the cylinder to flood. So I removed all 3 bowls and checked there operation and all looked good and were not hanging up. I put it back together and primed the system one carb at a time and the bowls filled and stopped then the primer got hard to depress on all cylinders. The only thing on the fuel system I have not done yet is remove all the needle's and check them out I think I am going to do that tomorrow after I put new gas,oil, and plugs in it. Thanks for the help.

 

[pnwboat]

Re: 1986 force 85 hp no power at WOT

You might also consider running it off of a portable tank to eliminate any issues with your fuel pick-up and debris in your regular tank as Frank suggested in post #6.

 

[emirikol0113]

Re: 1986 force 85 hp no power at WOT

Well I took the boat to a dealer and they diagnosed the carb's being bad (dumping fuel). 500.00 bucks. I had them rebuild all 3 carbs and picked my boat up 1 1/2 weeks ago. I went out on the water 3 times and on the 4th time problem came back. The only difference this time is on the way back in to the boat launch it was like someone was turning a switch on and off for one of the coils. I mean you could tell when it was firing correctly it would surge the boat it did this about 4 to 5 times and it was alive again. So I took it back out and it ran beautiful until I shut it off and started it back up,then it was back to misfiring again. I pulled all 3 plugs and #1 was wet #2 and #3 was black like it was carboned up. I believe #1 is dead but when I put a spark tester in-line it is saying it is getting spark. This motor is driving me nuts, and I dont want to send it to a dealer to have them tell me it is dumping fuel, to the dealers defense I guess it would appear to be dumping fuel if it is not BURNING it. Does anyone have the resistance checks for the coils,and the procedure? Also how do you properly check CDI units? Can anyone send me these via email ect.

 

[AmigoAzul]

Re: 1986 force 85 hp no power at WOT

I had same issue last year with same motor. I checked all connections and found a wire hanging on by one thread. The wire was located on the terminal block on the right side of the motor. I stripped it back and terminated it again. I then tugged a little on the rest and had to fix three more. All of the ones I fixed were just hanging by a single thread. I took it out and it ran like a champ.