Yamaha 9.9 surges

[robco]

I have a FT9.9ELF (1989?) that begins to surge after 1/3rd throttle, after a minute or two it quits completely. If I let it idle at dock or in gear (1/3 power), after about 10-15 minutes it quits. Took it to Yamaha dealer. He cleaned out carburetors, replaced plugs, and replaced CDI. I had rigged boat for remote controls and spliced trouble light to a standard 12 volt on remote panel. He said the Yamaha light is LED and standard 12 volt bulb fried CDI. I removed 12 volt bulb and put motor back in boat and problem is the same. No change.<br />Surges (very steady rhythm) and quits. <br />Any suggestions before I return the motor to the dealer?

 

[flyingscot]

Re: Yamaha 9.9 surges

Hi Jim: I have a 1987 200 HP that surges also..<br />in the 3000-4000 rpm range. I haven't figured it<br />out yet, but I'm still trying. I've got weak spark<br />in 3 cylinders. Maybe something under the flywheel. If I learn anything, I'll let you know.<br />I posted my problem 4-5 days ago. No responses<br />yet.

 

[jim dozier]

Re: Yamaha 9.9 surges

Does pumping the fuel bulb help? If so you need to rebuild the fuel pump. Surging sounds to me like a fuel issue not ignition. Did it ever run right after the mechanic had it. He did a lot of work on your money, did he test it afterwards?

 

[robco]

Re: Yamaha 9.9 surges

Thanks for the replies.<br />Mechanic is saying surging is probably a CDI "safety" switch that is caused by a short in wiring, etc. He tested motor in barrel, at idle and in gear, replacing water frequently, and said it ran fine (before latest malfunction). I doubt he can really test acceleration (in gear) in the barrel to any degree. I questioned fuel pump. He said it's fine. Pumping bulb does not make a difference. I'll post latest results as they occur.

 

[robco]

Re: Yamaha 9.9 surges

Mechanic's findings: He thinks the surging issue may be caused by the oil sender. I noted a "knocking" sound as engine warmed up. He heard the same thing in the tank. He pulled valve cover and said valves looked okay. So we've moved to possible additional problems internally. <br />Rod, piston, etc. So I packed the beast up and plan to tear it down at home. My labor is cheaper than his. And I bought a 2004 T9.9ELRC on the way out the door. I had reached my cost effective waterline on the old engine. So I really don't have the answer to the original problem, except for the mechanics hunch. All this boat stuff seems to do just fine, until you put it in the water.

 

[rodbolt]

Re: Yamaha 9.9 surges

find a better mechanic. its to expensive to go on hunches. use a larger tank with the proper test wheel and its a breeze to run at any RPM.<br /> good luck and keep posting

 

[WRCuddy22]

Re: Yamaha 9.9 surges

I have 1997 9.9 high thrust with surging problems which I had to squeeze bulb about every 5 minutes to keep it running. Yamaha tank, hoses, fittings all appeared ok. Pulled the hose connection out of the tank and the hose down to the filter at the bottom of the tank fell off. They use a plastic tube similar to an aquarium tank down to the screen filter and whenever the fuel level got down below the plastic tube it would suck air. Found the same problem in one of my relatives plastic tank this spring also. Both run great now!!<br /><br />John

 

[Grant S]

Re: Yamaha 9.9 surges

The fourstrokes have an oil pressure cutout which reduces revs to around idle if oil pressure is low. On the one I had I fitted a tee into where the sender fits and had an oil pressure guage fitted as well.(while in the tank) It showed good oil pressure at startup and then a slow decline once full operating temperature was reached when the cutout would come in. The symptoms seemed very carb like at first.<br /><br />With the price of parts it is a doubtful proposition to repair in my opinion.<br /><br />I think you made the right decision in buying the other motor.