C115 Need help have Money to spend. please read.

[walter lowe]

Bottom line is I need help with my 96 C115TLRU. I'm leaving for a bahamas trip in 5 days. Heres my story:

I came up with a bahamas trip to have an excuse to spend some time with my dad and make a desent documentary about something I enjoy at the same time (i'm a film-maker by day). I bought a boat with a 96 Yamaha C115 that had been sitting out of water and not properly stored for some time. Here's what I did.

1) I drained the tank and used Starbright enzyme for fuel systems in the tank, then I cleaned the carbs. I changed the water/sep filter and fuel filter.
- It idled poorly and maxed out at around 2500 rpm.
2) I rebult the carbs (gaskets, etc), new fuel pump, more fresh gas.
- It idled poorly but would achive WOT now.
3) Cleaned again and adjust carb floats to spec in manual and replaced corroded jet. Another new fuel filter and water/sep filter. Cycled through more fresh gas.
- BINGO. ran a half day with PERFECT WOT and perfect IDLE. Life was good. THEN AFTER an HOUR I LOST UPPER RPMS. If i tried to push it past mid range throttle it dies. But, if I apply full throttle and at the same time work the choke at about 1/2, I can get past mid range and achieve WOT with no choke. If contined with new fuel lines, more fresh gas and the problem persists.
4) The last straw. I hooked up a 2 gal port tank direct to the outboard.
- Ran for 35 minutes perfectly. PERFECTLY Then near end of tank, it died. Dont know if it was out of gas sucking air or it died for other reasons. hooked back up to main tank and had a really hard time starting (even though the primer bulb was hard). Got it started and I couldn't get past mid range again w/out choking it up there.

I got tired and brought it to my certified Yamaha Repair shop. Its been there for 2 weeks and they finally called today to tell me they may be able to get me an estimate and start repairs at the end of next week. I DONT HAVE THAT MUCH TIME. I had to take it home. There is no one in my area that can look at it in time. At this time I'd pay what-ever they wanted but 3 and 1/2 weeks to get an answer on a simple engine is crazy. Its a simple engine, no fuel injectors, no oil injection, no Hi-pressure fuel pumps.

Is there anyone that can help with some ideas about whats up. I've basically replaced everything in the fuel system. My next step will be to run it off a 6 gallon portable tank to see if it died on my last attempt cause I ran out of fuel in my 2gal or it was just a coincidence.
I havn't purued any electical system issues cause it just doens't really seem to fit the problem, but anyone that can help, I'd be happy to give credit to in my documentary film, or pay some type of service fee.

Thanks for reading,
Walter Lowe
wlowe@blackburst.net

[jb123]

if choking helps with rpms then youll need to clean carbs again.

rechanged plugs yet ?

try pullin each plug wire at a time,running on hose at say 1200 rpms, listenin for a non firing/fueled cylinder/non-faltering sound....if it falters, its firing.

try choking each throat with your finger, listening for an increase of rpms.

also , you can use a spray bottle of gas, and spray a bit into each throat, listening for an INcrease of rpms...whereas the extra it taking place of the deficient carb.

what is happening with your pump ball when this happens? have you pumped it whie error occurs?

observe the prop exhaust for unspent fuel, sign of a bad lp fuel pump.

[walter lowe]

thanks for the tips

Hey,
Thanks for the tips. I'm heading up to the coast where my boat is tomorrow. I'm planning on taking it out w/ a fresh 6 gal port tank and a spray bottle of gas.
I have pumped the ball while error occuring and nothing happened. While setting the carb float height, the manual gives the setting in mm of the gasket to float height, however it doesn't mention how much the float should be allowed to travel downwards as the fuel in bowl empties. I've set them to travel a pretty good distance, and I don't anticipate this being a problem since the error is intermittent and it will run great for quite a time before the error occurs.
What are the major items that cause intermittent failure? I would suspect a computer failure if the outboard had one, but it doesn't. Could it be remnent fuel contaminents, making it through the filters?
I'll change the plugs tomorrow too. THANKS JB123. your much more help than my local Yammy guys that I paid to look at it and say, "Give me a few more weeks."

-Walter

[jb123]

personally, i would stay away from adjusting floats.....unless someone here can give me a legit explaination how the tabs can get bent inside a carb bowl.....and if they COULD....the wire hangar would bend /spread first.

go thru each carb, break down as far as possible and clean each and EVERY orifice with a light gauge wire and spraying carb cleaner thru each also.

[walter lowe]

spray bottle

the motor responded well to the spray bottle. again on a fresh tank of gas, it ran for 20 minutes perfectly the died. but it responds to spraying fuel. what part of the carbs change with the engine warming up???