yamaha 9.9 problems

[Sheepdog172]

Hi All, I have a 1988 FT9.9ELG and can't get it started. Worked fine last year. First time out this season it wouldn't idle, could keep it running in neutral with the throttle full but when I slowed to shift, it would die.

Got hold of a manual & went through the maintenance. Still nothing. Went through the fuel system from tank to filter & got new gas. Nope. Thought it might be the fuel pump & replaced the diaphragm. No go. pulled the carb & cleaned out a bunch of grit but still no go. Now it's even worse.

I pulled the carburetor off the second time to make sure I didn't put anything in backwards. Afterwards, I was able to get it to run briefly but then it started backfiring through the air intake & died.

pulled the carburetor a third time to check the float setting again...looked okay to me but I'm not a mechanic by any means....after this I was only able to get it to run briefly while I held the throttle open. otherwise it won't start & I'm afraid I'm gonna ruin my starter motor trying to get this figured out.

I'm lost...anyone have any suggestions? I was thinking my float setting might still be off. How close do ya have to be to the specs? I used a cheap guage & set it at one inch. The float had a small crack but didn't seem to be 'waterlogged'.

Was careful to count turns when removing the pilot screw during the carb disassembly..think I got that right.

Where else should I look? The starter plunger & diaphragm looked okay but doesn't move when trying to start it...Should it move when the engine's cold?

Should I convert it to an anchor?

Thanks in advance,

Mike d

 

[vanner]

Re: yamaha 9.9 problems

sounds like the idle circuit in the carb is pluged, try to make sure the the small holes in the carb are clear use air pressure.

 

[IslandTractor]

Re: yamaha 9.9 problems

There are high speed and low speed jets on that carburator I believe. Sounds like the very fine low speed jet is clogged which is a common problem. I've not taken one apart myself but understand that you can clean the low speed jet with a single strand of fine wire.

After you get it cleaned you should probably change your fuel management to avoid this sort of thing. Stabil or other products would help as apparently does draining the carb bowl if you will not be using the engine for a few weeks.

 

[Sheepdog172]

Re: yamaha 9.9 problems

thanks for the suggestions...I'll pull it apart one more time. I ran fish some monofilament through the jets but musta missed one or didn't get it all the grit.

and what's this about fuel management? Ya mean one just doesn't park it until the next season?

 

[IslandTractor]

Re: yamaha 9.9 problems

and what's this about fuel management? Ya mean one just doesn't park it until the next season?

I think the new ethanol "enhanced" gas is giving outboard repair shops a lot of business. Ethanol is apparently a much better solvent than gas so it frees up old sludge and varnish from hoses and tanks which then ends up clogging filters and jets. I used to just add Stabil or something like it to gas but from now on I think I will run the motor dry in the fall.

 

[Yamajoe]

Re: yamaha 9.9 problems

Although i am leaning to a carb issue too, did you check compression and do you have a healthy spark? Discount these, then we can have a go at the carbs, throttle links. sinc again.