1986 85 hp Force - won't throttle up

gueppebarre

Cadet
Joined
Jul 6, 2008
Messages
6
Hi friends -

Hoping some of you pick up this post and give me a little help! Was out running the boat Friday, dropped off one tuber after having run the boat for a solid hour (turing it off and on numerous times and mostly at higher throttle), picked up the next "victim" and went out past no-wake zone and when we throttled up, heard a bit of rattling in the motor (thought we had snagged the tow rope!) that went away almost immediately, but then engine died. It started right back up, idled reasonably well, but couldn't get the RPM's past 3400 (usually runs around 4800 or a bit lower with a load of riders). Ran it back to dock, shut down the recreation, and decided to troubleshoot. Did the following things, more or less in the order given:

- found bottom carb bowl bolt leaking, pulled off and checked, was only loose - tightened up and tried, no change
- checked fuel delivery lines, fuel filter screen and fuel pump diaphragm - OK, no change in performance
- pulled plugs, all 3 had dark deposit, not wet, cleaned up, stuck back in - no change
- checked compression, 1-2-3 read 122 - 120 - 120
- cleaned carbs with spray cleaner and tried running - no change
- pulled all 3 carbs, opened up float chambers, cleaned the nozzles and jets thoroughly, put back on boat, tuned and synchronized choke and throttle plates, no change in performance
- tried a spare plug in each cylinder one at a time to see if one cylinder was dead; no change (cylinders all seem to be putting out something) - also could get RPM's to drop when spraying carb cleaner in venturis, so I think they're working partially
- hooked up auto timing light to test for spark, had spark on all cylinders at idle. Took out and throttled up, could not tell any difference in behavior of timing light (though it was blinking very fast) between cylinders. None were dying out for sure.
- checked spark advance mechanism, seems to be working ok, linkage is intact and moves quite freely

Today went out to test electrical components, found what may be an issue: tested resistance of the stator wires (blue/yellow on this unit). Disconnected the yellow and blue wiring; the one for 1/2 CD pack measured 440 ohms, the one for 3 CD measured 705 ohms. Spec calls for 680-800 ohms, so this is the first thing I've found out of sorts. Triggers all measure 47 ohms (spec is 45-60). Also, green/yellow stripe wires going to charging rectifier (and tacho) measure .7 ohms when disconnected - nearly shorted - is this right?

My question is simply - am I on to something - can a faulty stator cause this symptom - or am I chasing my tail? I think I've exhausted much of whatever else it can be. Fixing to pull the flywheel and look deeper (magnet came loose perhaps?). Can a poor stator cause loss of power like this?

Thanks to all; this forum is really something!

gueppe
 

sbake

Cadet
Joined
May 17, 2008
Messages
12
Re: 1986 85 hp Force - won't throttle up

Hate to point out the obvoius, but under load is the fuel pump delivering a sufficient supply of fuel? Don't know what thye correct pressure should be, but if you have a repair manual, it should give you that info. You didn't say if it is an outboard or I/O=Ldrive.

Steve
 

gueppebarre

Cadet
Joined
Jul 6, 2008
Messages
6
Re: 1986 85 hp Force - won't throttle up

Steve -

Thanks for the reply.

I will check it, but I did do the standard check of pumping the bulb while in operation and nearly flooded out the motor.
I suspect that if the fuel pump was cratering under load that I would improve the operation by pumping the bulb, correct?
I'm going to pull the fuel pump this afternoon and I'll post what I find.


Thanks again - gueppe
 

gueppebarre

Cadet
Joined
Jul 6, 2008
Messages
6
Re: 1986 85 hp Force - won't throttle up

Steve -

Thanks for the reply.

I will check it, but I did do the standard check of pumping the bulb while in operation and nearly flooded out the motor.
I suspect that if the fuel pump was cratering under load that I would improve the operation by pumping the bulb, correct?
I'm going to pull the fuel pump this afternoon and I'll post what I find.


Thanks again - gueppe

Oh, it's an outboard, model #856X6M.
 
Top