85 Force cold start and throttle question

[chuck11]

When starting, is it normal for throttle to be hard to push forward and motors rpms to increase very little? Motor runs good, when in gear it throttles up just fine, only when giving only throttle am i having a problem. Cold starting is my main problem. I just bought my boat and thanks to this sight i learned the proper way to start but still having trouble. Im wondering if it is because i cant give it full throttle im having my cold start problems. Any help is appreciated.

 

[bjhc100]

Re: 85 Force cold start and throttle question

Chuck11, is that a 1985 model if so what H.P. motor is it? I think it could be the shift/throttle safety interlock making it hard to shift, may need adjusting to completely disengage gear train. when starting. If it were the throttle or cable sticking it would be hard to move the throttle lever every time. HC

 

[fishrdan]

Re: 85 Force cold start and throttle question

Yes, what HP?

My 89 7.5HP (like 9.9 & 15) only throttles a little bit in neutral, keeps the RPM's about 1500RPM or less so the engine can warm up. When it's in forward or reverse you can go full throttle, but not in neutral. Probably designed like that so you can't peg the engine and shift it into gear, that wouldn't be too good on the lower unit's gears...

 

[chuck11]

Re: 85 Force cold start and throttle question

Its an 84 Bayliner with a 85 force. Thanks for the replys. Makes sense about not over reving the motor. I wasnt surebecause i just got the boat and havent been able to get the manual for it. Everything else seems ok with it. Just cold starting is the problem. I now know there is a procedure to follow. I didnt know about giving it throttle when starting. I had to give it a shot of staring fluid to get it going and this is when i noticed it didnt get alot of rpms and lever didnt go very far forward. im taking it out tomorrow so we will see if it starts better now. Thanks for all the help.

Chuck

 

[john from md]

Re: 85 Force cold start and throttle question

If your carbs and spark advance rigging are correct, pushing the throttle forward in neutral should only give you 1200 to 1500 rpm.

Force engines are known to be cold blooded and need choking and warm up.

Depending your loading and what pitch prop you have, that boat and engine combo should give you 35 to 40 MPH at 5000 rpm.


Regards,

John

 

[chuck11]

Re: 85 Force cold start and throttle question

Thanks for the help guys, took it out today and started up fine.thanks for the help. All have a Happy New Year.

Chuck

 

[jason32038]

Re: 85 Force cold start and throttle question

I have an 86 85hp force and it has always been a b&*(% to start. Bottom cylinder only has 10psi. Maybe changing the head gasket will help her start easier.

 

[john from md]

Re: 85 Force cold start and throttle question

Jason,

If you only have 10 psi in that cylinder, you definitely have a problem. It may be a head gasket, which is easy to change or it also could be damage.

You need to at least get that head off and see what is going on.

John

 

[jason32038]

Re: 85 Force cold start and throttle question

Already did that and it ran on 2 cyls. Found a loose wire to the cd box and it ran on 3 cyls VERY FAST. Then it was backfiring at idle so i adjusted the idle screw.........tested it out and it lost power and started backfiring and struggling to stay running. Turns out somehow I blew a hole on the side of the bottom piston that's about 1 inch high and an eighth inch in width. I dont think a simple idle adjustment would cause this. I have to overbore due to score marks from the broken piston and exposed rings on the broken side. The boat was sitting for 2 years prior to working on it and the bottom piston looks weak and brittle like charcoal. Maybe lean mixture? Going for a .040 overbore soon...should I keep the carb jets the same size? How much of a horsepower increase will i achieve? If i were to get 5-10 or more hp at the prop should I install a prop with a larger pitch to increase speed and keep original max rpm speed? Any ideas would be great. By the way it's an 86 85hp 3Cyl Force

 

[john from md]

Re: 85 Force cold start and throttle question

A lean mixture in a Force engine will cause detonation which will put a hole in a piston. This can come from obstructions in the fuel path, float level being too low or mixture needle being turned in too much. Since force engines use the idle system throughout the speed range, making the idle circuit too lean will cause lean burning at high rpm. Never go below 7/8 of a turn, and better, stay 1 turn out.

Over boreing this engine doesn't give you much at all and I would not change anything. The main thing you want to find out is why it was running lean in the first place.

I suggest that you PM Frank Acampora about your rebuild.

John