trouble starting or keeping started 1991 Force 90

[awatney]

Hi, I am having trouble getting an outboard started and to stay running.

I have just replaced a piston on a 1991 Force 90 outboard motor. I have reassembled the motor, put fresh fuel and oil mixture, checked for spark and installed new fuel line and primer bulb. The bulb gets hard when pumped. I have played with the idle mixture screws first trying 1 1/2 turns out, then 1 turn and currently 3/4 turns. The motor turns over quickly (I rebuilt the starter and cleaned the connections). There were two main problems with the motor before rebuilding.

1. Number 2 piston lost a ring and was replaced.
2. The plastic piece at the top of the tower shaft that connects to the spark advance screw was broken off and replaced. I don't know what the original settings was for the screw.

When I try to start the motor I will either get a back fire through the exhaust, it will start and run for a second and a half, or it will just crank over with nothing. When it does not start, I pulled the spark plugs out and they were wet with fuel. I will let it sit for about 1/2 hour, try again and get the same results.

One thing I do notice is that there seems to be a lot of fuel in the carburetor, no not the fuel bowl, but inside the carb. So much that if I flap the choke valve closed and open it splashes out.

Any help or suggestions would be appreciated.

thanks,

Allan

 

[awatney]

Update: I checked that TDC was where it should be and when the number 1 piston is at TDC, the mark on the flywheel lines up with the block.

 

[Jiggz]

First, you need to reset the fuel air mixture screw to at least 1 turn out or even better 1 1/8 turn out from slightly seated. NEVER SET THIS SCREW TO LESS THAN 1 TURN OUT!

You need to verify timing first. Using a timing light, set the WOT timing to 32 BTDC (static). If the carbs continue to show fuel flooding, make sure the choke valves are not inadvertently closing. Also identify which carb is flooding. To start a flooded engine, remove the engine cover and manually open fully the carb throttles using the tie bar and then start cranking while holding the throttle wide open (you will obviously need a second person to do this unless you have a remote starter). It will take a little bit maybe two or three times cranking up to 5 secs each time to get rid of the excess fuel. If fuel continues to splash out of the carbs, identify which one and then you will need to dismount that carb and inspect the reed valves.

 

[awatney]

Thank you for your advice.

I turned each air fuel mixture out 1.125 turns, then turned to repairing my timing light (broken clamp).

Once repaired I put the control lever in WOT, jumped the safety switch, connected the timing light and attempted to set the timing. However, I could not even see the timing marks for each strobe flash. This is similar to having a sheared off key on the fly wheel or the wrong fly wheel was installed. I ended up labelling TDC for each piston on the top of the fly wheel and numbering them 1 through 3. Then when I crank the engine, the tape with number 3 lights up. I moved my timing light pickup to the number 3 plug wire, and voila, I can see the timing marks. It turns out the last person who worked on this engine, connected the number 1 coil to the number 3 CDI lead and visa versa. That would explain the backfire through the exhaust. I switched the two leads, cranked the engine and found the marks and was able to line it up to 32 BTDC. After reinstalling the plugs and connecting the wires and without engaging the choke, the motor started and ran until I turned the key off. Yeah!

I have since put the water muffs on and tried to let it run for a bit, but there is an awful lot of smoke. Could this be due to the oil I added to the cylinders and bearing after I reassembled the motor? I will try to burn some of it off tonight, but the motor is in my garage which fills with smoke quite quickly. I checked the insides of the carburetors after running for bit and they no longer seem be filling with fuel.

Thanks again for your advice.


Allan

 

[Jiggz]

Great. As for the heavy smoke you need to be aware this is a 2 cycle motor and they do smoke albeit a little heavy. Just make sure you use a correct fuel oil mixture 50:1. You can try burning off the existing mix if the mix ratio is unknown to you. If you have a spare external tank you can try running it with the correct fuel oil mix ratio and see if the smoke is really that heavy. As for running the motor extended on idle, I do not recommend doing this instead take it to the water and burn it off in there. Prolong idling is really not very good for these engines

Now you mentioned "reassembled the motor" could the heavy smoke be due to break in fuel oil mix which is 25:1? If such yes, heavy smoke will be normal during break in period. When you are done completing your test runs at the new timing of 32 BTDC static, can you post your engine performance. I understand it says in the sticker it should be set to 32 BTDC but that should be dynamic. Normally, the static is set to 2 degrees below dynamic hence in your case should be 30 BTDC. But if the performance is great then you can just keep it at 32 BTDC. Stay posted.

Lastly, label the plug wires for future reference. To make them idiot proof use, " Top, Mid and Btm" or even better "Top, 2nd fm Top and 3rd fm Top". 1, 2 and 3 labeling is just not idiot proof enough as other will start counting from the bottom instead of from the top. Lol

 

[Poncho Villa]

Lastly, label the plug wires for future reference. To make them idiot proof use, " Top, Mid and Btm" or even better "Top, 2nd fm Top and 3rd fm Top". 1, 2 and 3 labeling is just not idiot proof enough as other will start counting from the bottom instead of from the top. Lol

:lol: You must have seen me work at some point! :rofl:

 

[awatney]

Hi,

Heavy smoke is gone. I pulled the boat out of the garage, put on the water muffs and ran it for a good 10-15 minutes. Now it just smokes as it should (I guess) but no more thick white smoke.

You'd think the wiring for the coils would be self explanatory, top coil to top cylinder. I found the number 2 coil, um 2nd from the the top or 2nd from the bottom, was not firing. I did a swap with the top coil and it started working again, maybe by unplugging the wires and plugging them back in fixed it. I don't know. I can't get the engine to idle correctly, I have to hold the throttle open ever so very slightly open in order to keep it running. I'll try to re-synch the carbs to see if that helps. The throttle CAM (if you can call it that) barely touches the throttle follower and I have adjusted it to the maximum setting but I can easily spin the small plastic throttle cam follower thingy. Maybe it's worn out.

I will label all the wires, but it is running and goes into gear, etc. Just need to put a prop on and get it to a lake for the real test.

thanks,

​Allan

 

[SkiDad]

the roller is supposed to spin - but you unlock the nut and turn it so it touches the cam. you really need to go over that again b/c i think your idle will not be right the way you have it now. Frank has a video explaining it above and there is also a FAQ about it. Takes a few times to get it right.

 

[Jiggz]

No Title

That is correct. The roller is actually mounted on an eccentric screw meaning is has a lobe in it which allows the roller to move closer or farther from the cam. And to adjust it, you need to loosen the nut at the back of the screw rotate it until the roller is just touching against the cam's marking (pick up point). Now this is with the idle screw (bottom of control tower) not pushing against the engine block but barely touching and the cam's marking should just start touching the roller (see pics).

After adjusting then you can adjust you idle RPM using the idle screw located at the bottom of the control tower.

 

[awatney]

Okay, the motor is running better now that I re-synched the carbs and set the eccentric screw properly. The final test will be to take her to a lake and see how it reacts with a load. But first I want to check the impeller and replace if necessary. The motor has been sitting for a while.

thank you everyone for your help with this.

Happy boating,

Allan