89 Force 50, I'm am ready to drop it in the lake

[Scooter 2]

I purchased an 89 bayliner capri with the original force 50 engine. The motor idles rough sometimes and great others, it uses an incredible amount of fuel some of which is flowing back out of the carb into the engine case. I can not get the engine to rev above 4000 rpm. The motor seems to miss at all rpms.

I have cleaned the carburetor, replaced the reed valves, checked the ignition timing, ensured the appropriate prop is installed, rebuilt the fuel pump, installed a new fuel bulb. The compress test was 135 on both cylinders. I have also checked the ohms on the stator. There are two sets of winding for ignition with blue and yellow leads. The third set having green wires is the ac side. The ac windings are good. One of the two ignition windings is bad; having no continuity. The fine fellows at CDI told me that the engine only needs one winding to operate as this stator was used for three cylinder engines as well. The second winding is fine. The ohms are around 750. I checked the ohms on the trigger and they were 50 as per spec. It appears to have a strong clean spark on both cylinders. I replaced the plugs this morning and after two hours of run time they are black and gummy.

WHAT HAVE I MISSED???!!!!!!!!!!!

 

[jerryjerry05]

Re: 89 Force 50, I'm am ready to drop it in the lake

Ethanol might be part of your problem.See the pic.This hose is a fuel line that was used as a siphon hose.Not anymore !!!The fuel lines could be delaminating and feeding your carbs gunk.How about bad fuel? You have a water/fuel seperating filter?The fuel comming back is from a float/needle not set.Bad diaphram.Even new can go bad.
Low speed air setting? In till it bottoms out.Then back it out 1 and 1/8th turn.Start it in the water.Warm it up,put it in gear.Air screw in till it stalls/balks/coughs.Then out 1/2 turn.Then set idle to about 750rpm.
Top RPM could be low because your overloaded. You should have 1-2 adults 1-2 kids,cooler.1/2 half tank of gas. You might need a new prop,the old might be pitched wrong.J

 

[Scooter 2]

Re: 89 Force 50, I'm am ready to drop it in the lake

Thanks for responding Jerry. The fuel hoses have been replaced and I checked the float adjustment. It is 3/16 from the carb base as per spec. Could be a bad seat. It is new but anything can happen. I had the fuel pump apart again today; no signs of damage there.

I have set and reset the fuel air ratio. I bottom out the screw and turn it back 1 turn. I then lean it (the rpm never changes) out until it coughs. When I turn the screw back out there is no difference in engine rpm. The only change is the lack of lean pop. The screw can be turned until it is loose and still no difference. The needle is not worn at all. I am wondering if I have a crack in the carb body; although I can't see one. Like I said earlier the new plugs I installed are showing signs of a very rich mixture. The top plug is slightly worse.

As for overloading; it will not get to full rpm with just me and a tank of fuel in it. Maybe 220lbs. The boat is rated for 600. The original documents claim 29mph with a full load at 5500rpm using the prop that is on the boat. The prop shows signs of use; but no damage or twisting.

Initial throttle response is good and seems to die as rpm climbs.

If you have any further ideas I would love to hear them. I am a ex auto/heavy equipment mechanic. I understand the principles; however I recently discovered I have some learning to do when it comes to outboards. Your advice is appreciated.

 

[puddle jumper]

Re: 89 Force 50, I'm am ready to drop it in the lake

I had a similar problem with my 50 hp force. Check in behind the fuel pump there is a fuel recalculation system that the manual does not go into great detail. When I took mine apart and the screens were clogged with carbon. After I cleaned them, my engine ran great all summer.

 

[Scooter 2]

Re: 89 Force 50, I'm am ready to drop it in the lake

Thanks puddlejumper. This is something I have not tried. I will look and let you know what I find.

Thanks!!!

 

[Scooter 2]

Re: 89 Force 50, I'm am ready to drop it in the lake

I went out and pulled the fuel pump and the plate behind it off. There are no screens on mine. The part is a solid machined part. Behind it is the intake ports for the top cylinder. I will take the bottom plate off tomorrow and have a look see.

 

[jason32038]

Re: 89 Force 50, I'm am ready to drop it in the lake

When I disassembled my engine I checked the idle mixture screws just for the hell of it and they were all set at 1 1/2 turns out and the engine was completely stock. Also if you have no screen I suggest you install a non paper inline filter.

 

[blueoval78]

Re: 89 Force 50, I'm am ready to drop it in the lake

29 MPH with a full load? Really? I just had my motor completely tuned by a professional marina; it seems to be running great and I can only get 28 MPH with 250 lbs in the boat and 25 MPH with 400 lbs in the boat at best. I've tried changing trim positions, distributing load, changing props, etc. I'm currently running a 13.5 pitch prop which gives me 4500 RPM's at WOT. If I drop down to 11.5 pitch, I'm at 5000 RPM's but drop down to 25 MPH at WOT with 250 lbs in the boat.

 

[Scooter 2]

Re: 89 Force 50, I'm am ready to drop it in the lake

Thanks for your replies. it seems I do have a crack in the carb body. I got a used carb online and rebuilt it. The boat runs better than ever. Revs out at 5500rpm. No more fuel pouring out of the carb.
Bayliners original specs that came with the boat weren't far off...30mph with just me a tank of fuel and my border collie (260lbs). That speed coming from a GPS; using an 11-1/2 pitch prop 10" dia.