9.9 Yamaha

[Reelin In The Years]

Fishing out of Nanaimo yesterday and it was fairly nice out, so I thought I would drop the kicker and fish using it. It started up right away and I let it warm up while I connected the steering arm to the big motor. I put it in gear and turned the big motor off. It ran fine for a bit then I noticed it started to idle down so I squeezed the ball and the rpms came back up. It slowed again and I squeezed the ball again. The rpms came up again and again the rpms went down. I left it alone and eventually it stalled. I squeezed the ball and started it. Hard starting, but started. Put it in gear and it stalled again in a bit. Stopped using it.

When we got into the bay I started it and same thing. Put in gear and stalled right away.

Today I tried hooking up to portable tank with fresh gas. Same problem. Only way I can get it to run is to constantly squeeze the bulb.

Would this be an indication of a week fuel pump? Don't see it leaking anywhere and checked to see if there was any gas in the oil. Seems like it could be a week fuel pump, if it will run with me pumping the ball.

Thanks for any replies.

 

[Ringo]

When was the last time you used the kicker? Maybe it's a case of old gas and gummed up carb jets. You may want to clean the jet before touching the fuel pump.

 

[brutus]

Your sucking air somewhere is my guess, go trough all your gas line and make sure they’re secured and in good shape, could be your primer bulb too. If that don’t work, like Ringo said carb. Those connection from the hose to the kicker are not sealing properly sometimes

 

[ship happens]

Fuel pump

 

[N2013]

Tighten all connections, replace filters, replace bulb, run some seafoam through it. . That’s the low hanging fruit, anything else is above my pay grade.

 

[Brando]

is it a day tank was the vent closed?

 

[brutus]

Ship happens, is a boat mechanic so there you go

 

[tubber]

The pin that holds the piston in the fuel pump of my 50hp Merc has fallen out twice.
Pumping the bulb was the only way to get home. One pin fell in the basin with the dirty oil on my last oil change.
Dangar has a good video explaining about the diaphragms and other fuel pump parts.

 

[ship happens]

Pretty easy to tell on those pumps. Pull the hose off the pump. The one that feeds the carburetor and crank it over. See if it pumps fuel. Either that or pull it off at the carb. Crank it. See if fuel comes out.

If it's NFG it will be either one or both of the diaphragms, stuck check valves flap, or like mentioned above, stuck piston

 

[Reelin In The Years]

So, as mentioned in the beginning. My kicker runs off my inboard fuel tank which also supplies fuel to my main motor, 140 Suzuki. No problem with my big motor running. Gas comes to Racor filter which services both engines. Open 1 valve for big motor and close kicker valve. Open valve for kicker and close valve for big motor.
Today I used a new gas line and hooked it to portable gas tank. Same results. Only way it will run is to squeeze the ball constantly.
Thanks for all replys.

 

[profisher]

Not sure what year 9.9 it is but the model big block 9.9 made before 2007 (actually a de-tuned 15hp) had fuel pumps that would vapour lock once the inside cowl/hood temp rose and the fuel in the pump and fuel line warmed up. Same symptom..mine would run fine for maybe an hour or two..less in strong winds and current when I had to throttle up and temps rose quicker...then it would start to die unless you got to the primer bulb before it did. I had a water cooler made at Harjim in Victoria after SG Power couldn't solve the problem...we tried different temp t-stats....but it didn't completely prevent it. The cooler did. I got $175 in Yamaha bucks for my R&D and solving Yamaha's issue. SG had a dozen other guys with the same problem. SG asked Yamaha what should they do...they sent pics to Yamaha and got the word to make 12 more for those guys. I have a few of them here which were tossed into the dumpster when SG folded. If you have the same model your welcome to one of them.

 

[profisher]

Here is what they look like..you just need 4 longer screws for the pump body and some Silicone sealer to attach it.

 

[Reelin In The Years]

Here is what they look like..you just need 4 longer screws for the pump body and some Silicone sealer to attach it.

Thanks PF. My 9.9 is a 2006. My pump has 2 spouts on it that water hoses get attached to for cooling. My motor does not run long enough to get hot.

Good ingenuity on your part.

 

[profisher]

Thanks PF. My 9.9 is a 2006. My pump has 2 spouts on it that water hoses get attached to for cooling. My motor does not run long enough to get hot.

Good ingenuity on your part.

Then as others have said the pump diaphragm has failed..they either won't pump or can allow fuel into the crankcase. I know in one case from SG where the pump allowed oil into the fuel and a new motor smoked blue. Yamaha replaced the powerhead at 10 hrs and it smoked too...then they found the problem was the fuel pump all along. . I ended up with the 10 hour block as a spare a few years later as it was just sitting on a shelf as Yamaha never asked for it back. Got it for $500.

 

[Reelin In The Years]

Then as others have said the pump diaphragm has failed..they either won't pump or can allow fuel into the crankcase. I know in one case from SG where the pump allowed oil into the fuel and a new motor smoked blue. Yamaha replaced the powerhead at 10 hrs and it smoked too...then they found the problem was the fuel pump all along. . I ended up with the 10 hour block as a spare a few years later as it was just sitting on a shelf as Yamaha never asked for it back. Got it for $500.

That's a good deal for a powerhead. Always nice to have a backup.

 

[Tieoneon]

Yamaha 4 stroke 8 hp hi thrust rough idle running super rich, adjusted low speed jet and no difference. Will run with jet fully closed. Any ideas?