1988 Force 85 loses power

rogerwa · Sep 4, 2002

I would not rule out fuel just yet.. Did you pump the bulb when the loss in power occurs? You may be sucking air in your fuel line or your carb float may need adjustment. You may also try a different portable tank setup to ensure you do not have restriction in your intake or water or gunk in the bottom of the tank. Also, you may try to run the engine without the cover to ensure you are not leaking exhaust into the cowling. Since you mentioned a problem wiht the exhaust boot it is something easy to look at. This could choke your motor as well.

rogerwa · Sep 4, 2002

Re: 1988 Force 85 loses power

I take it then that when you reduce throttle and idle for a while that it still does not throttle up? If it doesn't then I would be looking at if you are dropping cylinders. Does it idle rough when you go back to idle? Also, do you have good water flow and temp? What is your WOT and prop pitch?

DanM · Sep 4, 2002

1988 Force 85 loses power

I have the classic intermittent power problem -- engine works fine within five miles of a mechanic. The rest of the time I lose power at high speed and my 17' Bayliner drops from 30 mph to about 10. Runs like that for awhile, then sometimes goes back to full power. Sometimes not. Sometimes it starts and runs fine after being off overnight. Sometimes not. Suspected fuel but have switched and refilled tanks several times. There was a leak in the exhaust boot that a mechanic said could have caused problem by spraying water around engine compartment, but fixing it hasn't helped. Mechanic (I am not one) says compression is good and he put in new plugs. Mechanic did say something about wrong color power pack (?) installed by previous owner, but that it seems to work. Starts and idles fine consistently. Any ideas appreciated.

DanM · Sep 4, 2002

Re: 1988 Force 85 loses power

Forgot to add that despite possible wrong color pack the engine performed perfectly for two seasons before problem started.

DanM · Sep 4, 2002

Re: 1988 Force 85 loses power

Tried both, thanks. Pumping didn't help but running without the cowl seemed to until I got the rubber boot replaced, but now there does not appear to be a leak and the problem is back.

DanM · Sep 4, 2002

Re: 1988 Force 85 loses power

Water flow looks good. Don't know what WOT is and I don't know the pitch off hand, but when the engine "kicks in" I get perfectly good speed and power. Idle seems smooth.

DanM · Sep 4, 2002

Re: 1988 Force 85 loses power

I've spent a little more time reading other posts and calling a mechanic and have two more clues/questions. One, the insulation inside the outboard housing was rotting and was removed a week ago. Maybe some of it is in the carburator and creating a blockage, but would this only effect high speed operation? Also, I notice that on newer engines the shaft well is separated from the engine compartment. My shaft has water in it and I suppose, without the insulation keeping the engine area smaller, that water could be kicking up into the intakes. Second, a mechanic says it is probably the stator, but would a stator fail in such a way that the engine ran fine at high speed sometimes, then lose two thirds power at full throttle itermittently?

karvin · Sep 4, 2002

Re: 1988 Force 85 loses power

This is exactly the same symptom as my 1988 Force 15HP and my mechanic thinks its really the coil packs that are bad. The theory here is they are taking out the condensors and so you don't get full spark and minimal combustion. I checked my plugs right after it happened while on the water and they were not overly fouled and seemed fairly normal with a slight hint of fuel. See my post about the Force 15HP. I was going along full boar and then the darn thing cut down to minimal power. My idle was also way off and rough after that. It was an extremely hot day so mine may be heat related. I'll fire up the motor cold and see if the power comes back in idle and forward.

DanM · Sep 4, 2002

Re: 1988 Force 85 loses power

My idle continues to work fine during the power losses at high speed, and sometimes the high speed operation works fine cold and sometimes it doesn't. Also, it never conks out.

karvin · Sep 4, 2002

Re: 1988 Force 85 loses power

Can you rev up the motor normally during idle or does it seem like it is still being restrained? Just questions, no answers, but at least I have someone to compare with. Supposedly you can take multimeter readings on the coils while they are at rest according to the manuals but this probably won't determine much.

DanM · Sep 4, 2002

Re: 1988 Force 85 loses power

My boat has the standard (abysmally stupid) single lever throttle and shift, so I can only rev it to the limit of the the starting lever. It works and sounds fine when I give it gas. When it loses power at high speed it sounds simply as if I am giving it less gas, but it remains smooth.

karvin · Sep 5, 2002

Re: 1988 Force 85 loses power

That idle throttle limit seems similar to mine. Frankly I'm waiting for the electronic conversion ignition kit to hopefully solve the problems.

Outrage 19 · Sep 5, 2002

Re: 1988 Force 85 loses power

One time while I was running an Evenrude 35 I had a peace of foam about the size of a gulf ball got sucked into the carb. It idled fine and accelerated smooth but never reached full Rs at WOT. I used a peace of wire to pull it out and after that it ran fine.

DanM · Sep 10, 2002

Re: 1988 Force 85 loses power

And the winner is...my new mechanic found no spark on middle cylinder, replaced cd module, and it is now running fine at all speeds. Thanks for everyone's input.

1988 Force 85 loses power

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