Force 85 Throttle Issues.

[SoundWave]

I recently picked up a 1988 17' Bayliner Capri with an 85 hp Force outboard. At first, it was either it would idle poorly and accelerate well - or idle well and accelerate poorly. I had to fiddle with a few different parts (idle stop screw, throttle cam, roller, etc) in order to get the motor to idle nicely as well as open the carbs as much as possible, but mechanically - it seems to be in order now as both ends of the spectrum are much improved. My problem is - the engine seems like it has more to give. I know it's only an 85 hp but you can just tell by listening to it when the throttle is fully thrown that the rpm's are lower than possible. When I push the throttle control forward into gear, it seems fine - but from that point forward to where the engine actually starts to accelerate is about 25-30 percent of the throw that is "dead". In other words, If I'm looking directly at the throttle handle - from 12 o'clock to about 11 o'clock is where it clicks into gear - but from 11 to 10 o'clock I get nothing and the shortened acceleration takes place only from 10 to 9 o'clock. The shift and throttle cables that came on this boat are about 3 feet too long. Might that have something to do with it? I played with the nut and threads on the quick connect at the engine, but it didn't do anything. I just genuinely feel like my current WOT is not true WOT for my setup. Whatever you guys can suggest from your vast experience and knowledge databases would be a huge help. Thanks in advance.

 

[john from md]

Re: Force 85 Throttle Issues.

First of all, you need to get a factory manual or Clymer manual if you are going to play with the rigging.

Next, we need to know what RPM you are getting at WOT and the pitch of your prop. If you have a speedometer or GPS, your speed at WOT will also be helpfull.

Regards,

John

 

[SoundWave]

Re: Force 85 Throttle Issues.

Thanks for your input John from MD. I have both the Clymer and factory manuals, which guided me through the rigging modification process. My speedometer and GPS are both busted - so unless I buy an RPM testing device, I'm limited to visual and audible observation at this point. As for the prop pitch - my tilt/trim is all the way down while running. What do you think of the excess cable lengths? Any potential "connection" between my problem and the mismatched cable config? I look forward to anyone's response. Thanks again.

 

[john from md]

Re: Force 85 Throttle Issues.

As long as you can rig the throttle and shift cables per the manual, length is no issue. Since the inner and outer cables are the same length, the only impact they have is taking up more space.

On my boat, there is less response in the 12 oclock to 1000 range than there is from 10 oclock to 8 oclock where my forward action ends. This is really a function of the power band of the engine. Things like carb diameter, piston size, reed size, timing all come together to give you a certain power band.

If you polish your ports, change your jets, change your timing etc, then the engine may respond more at the lower end of the band than the upper end.

Hopefully, this will help you understand that throttle position doesn't necessarily equate to throttle response.

You can easily check to see if your throttle plates are fully open when the throttle is fullly forward. If they are not, then the linkage needs adjustment.

Without at least a speedometer or handheld GPS, there is no way to determine how your boat is performing.

Several places sell a Garmin Etrex handheld GPS that work great for boating.

Regards,

John

 

[Frank Acampora]

Re: Force 85 Throttle Issues.

As John said, cable length is no problem. These engines REQUIRE a loop of cable at the engine end (in the splashwell) in order for them to shift and throttle properly. Too short cables will bind and cause all sorts of aggravation.

And without some sort of instrumentation, 4000 sounds no different than 5000 RPM. The ear can tell if RPM is changing, but unless you have perfect pitch, you cannot discern what the actual RPM is.

If you have power trim, and the engine is trimmed all the way in, hit up and listen to the RPM. As the engine trims up RPM will rise until you go too far and the engine starts to cavitate. Then you back down until the prop locks up again.

If you do not have power trim, then you need to experiment with the tilt pin adjustment to see which holes give best performance. Generally it will be second or third hole out.

Lastly, the final 1/4 of control lever travel will open the carbs from 3/4 to full. The engine makes a lot more noise, uses a lot more fuel, and the boat goes only 2-3 MPH faster. Not really what you would expect--makes it seem like there is no response. Reason is that timing is fully advanced at about 3/4 throttle (for fuel economy) and final throttle travel is just to squeeze the last couple of ponies out.

 

[SoundWave]

Re: Force 85 Throttle Issues.

Thanks fellas. I really appreciate your insight. I'm taking all of your points into consideration. This is a great place for me to learn. Keep it up !!

 

[JoeCrow]

Re: Force 85 Throttle Issues.

As mentioned,
You really need a tach to see what your WOT actually is,
judging by ear isn't always the best way to go
There are some "minitachs" out there that are fairly inexpensive
check out http://www.enmco.com/
They're available on e-Bay for about $27

 

[RivahGurl]

Re: Force 85 Throttle Issues.

I as well just bought an 87 17'f capri and it came with the 85hp force motor. Im having major throttle issues. Mayeb you can help me. I am wondering is there a button or switch somewhere to realease the gas throttle to make it move? I am so new at all of this and so lost!

 

[john from md]

Re: Force 85 Throttle Issues.

In order to give you some suggestions, I need to know more about what your engine is doing.

Tell me everything about how it acts from starting on up.