2000 Johnson 9.9 WOT problems

[HittinSteel]

Hi Guys, my first post here. Been lurking for a while, but have a problem now and hope I can get some troubleshooting opinions.

My 2000 Johnson 9.9 has developed some running issues. I first noticed that the motor would reach WOT (5200 or so) and then began loosing rpm's (about a 1000). I brought the motor down to idle speed and it stalled. I inspected the fuel line between the tank and motor and saw a wet spot of gas between the pump bulb and the motor. As an on the water fix, I wrapped some electrical tape around the area. The boat fired and ran wide open throttle back to the dock (about a 15 minute run).

I replaced the bad section of fuel line only with the correct diameter automotive fuel line. I used the screw type clamps.

This weekend, the motor ran fine, but then the symptoms reappeared. During the day there were several times I ran the motor for 15 minutes or more at WOT with no problems. When the motor bogged at WOT I tried to manually pump the fuel line but the bulb was already hard.

I have taken the fuel line off and I can press the bulb as hard as I can and I get no change, so I assume there is not a leak in the line. My fitting at the tank appears to be a little loose......maybe it is sucking some air there?

Any ideas what to try next?

Thanks,

Bryan

 

[Rick.]

Re: 2000 Johnson 9.9 WOT problems

Once your engine is running, and pumping it's own fuel, your tank to fuel pump hose is sucking gas so normally the bulb should be soft. Not sure why yours would be hard during normal operation. I would pull the screen on the pump and check for cleanliness and as well pull the tank pick up line and check the screen on it as well. If that pans out then I would move to the high speed circuit of your carb. which will require a good cleaning and I would recommend a new kit at the same time(provided you haven't kitted it recently). Best of luck. Rick.

 

[HittinSteel]

Re: 2000 Johnson 9.9 WOT problems

Thanks for the response Rick. I just pulled the O ring on the fuel line tank fitting and found it to have some damage. Could be sucking air there.

Have a friend with a known working tank and line. I'll try it this weekend. If it doesn't solve the problem then I'll look at the tanks fitting and then on to the fuel pump screen and a kit and ultrasonic cleaner bath for the carbs

 

[Rick.]

Re: 2000 Johnson 9.9 WOT problems

That should make a difference. Be sure to let us know how it is going. Rick.