79 Evinrude 9.9 hp fuel flow problem

[Jondog]

I sure hope that someone can help with this.
I have a 1979 9.9 hp Evinrude that my family has owned since new. It has low hours and was originally used as the 8' dinghy motor on my family's 1966, 36' Chris Craft. This motor was always run in fresh water after all salt water use and has always been maintained meticulously. I now use it on my 15.5' welded aluminum bass boat and up until recently it has performed flawlessly and always fires right up and even puts the bass boat up on a plane easily. The problem is that once started after running for a time at any speed the motor will die unless I pump the bulb on the fuel line. I originally thought that might be part of the problem so I replaced the line, then when that diidn't do the trick I replaced the fuel pump on the motor, that didn't fix the problem either. I noticed that it seems to smoke a little more than normal too. I also have tried leaving the cap open to make sure it wasn't a tank vent problem. I'm beginning to wonder if it may be a carb problem and if so, I have rebuilt my carb on my Harley so I should be able to handle the Evinrude? Any ideas out there? Thanks.

 

[Rick.]

Re: 79 Evinrude 9.9 hp fuel flow problem

great motor, I have the same. Have you inspected the suction screen to make certain the motor can draw gas freely? What you describe would normally be fixed with a new pump but given it didn't help I am thinking something is stopping fuel flow. Best of luck. Rick.

 

[Jondog]

Re: 79 Evinrude 9.9 hp fuel flow problem

Yes, I did clean the suction screen when I replaced the draw tube attached to it with a new one, as it was slightly bent and had somewhat of a crimp in it. I spoke to a tech yesterday that seems to think that I was right in my next course of action in cleaning and rebuilding my carburetor. Seems there is a lot of that going around with some gasoline containing as much as 10 percent ethanol these days, he said it tends to loosen all existing dirt and resin in the tank and fuel lines and it sometimes will get stuck in the carb. My factory rebuild kit should be here in a couple of days if UPS is on time. Meanwhile the new coupler for my washing machine should be here tomorrow so I will fix that and start getting rid of this pile of dirty clothes. I'll let you know if rebuilding the carb does the trick. Any idea on a horsepower boost, I've heard of putting the carb from a fifteen horse on a 9.9, I wonder if you could just change the jetting?
Thanks for your help,
Jon

 

[Rick.]

Re: 79 Evinrude 9.9 hp fuel flow problem

It's never a bad idea to give an old carb. a new kit. Your mechanic is right about the ethanol fuel. Avoid using it if you can. Your symptoms don't really sound like the carb. to me. Given the replacement of the hose and draw tube, is there any chance you could have a leak at any of the fittings? If you were getting air into the suction line it would line up with your symptoms. As a temporary measure, I have replaced the fuel line from the pump to the carb. with clear plastic hose. It is very cheap and allows you to see if the carb. is getting robbed of gas. Rick.

 

[kbait]

Re: 79 Evinrude 9.9 hp fuel flow problem

If the fuel line connectors' o-rings get nicked, they'll let air in, and you'll have to pump the bulb to keep running. Common problem, cheap fix.

 

[jay mendoza]

Re: 79 Evinrude 9.9 hp fuel flow problem

If you have a fuel bottle, fill it with pre-mix, hang it over the engine and connect it to the carbs fuel inlet. If the engine runs fine, your problem is fuel delivery to the carb. This could be fuel line fitting orings(see above), leaky fuel lines from and to pump in lower cowl, or a vacuum leak between the pump and crankcase.

 

[andrewkleffner]

Re: 79 Evinrude 9.9 hp fuel flow problem

I have the same outboard motor. I have a quick question i had a guy clean the carb. to start it i have to choke it then restart it and for it to stay running i have to give it gas. just curious why it wont stay idialing without giving it gas. sorry if this is confusing im confusing myself

 

[Rick.]

Re: 79 Evinrude 9.9 hp fuel flow problem

Please start a new thread of your own. This is almost two years old. Rick.