Fuel Delivery Problem 9.9Hp Evinrude 1976

[OptsyEagle]

My motor has a problem. Sometimes when I run it, when it is later in the day, 1:00pm etc. and it is real hot out, it fires up OK. However, you can sometimes get about 30 yards out and it starts to hic cup and then die. I noticed it last year and I knew that the last time I cleaned the carb I did not put the little spring on the inlet to float valve, since the one I took out did not have one. So, last year I thought that my inlet valve must be sticking so this spring I took the carb apart, cleaned it and inserted that spring properly.

Now, whenever I ride it in the cooler morning weather, it seems to run great, but when the day gets warmer it seems to have this problem. Yesterday, when it did this, I squeezed the primer bulb (it was getting soft, might have even been compressing) and the motor came back to life, but wanted to repeat the problem again, another 20 yard of travel. The tank is a plastic one with the tank vent screw completely open. No gas, that I can see, is leaking from my carb or fuel pump or any of the lines.

Any idea what the problem might be and/or any tests I can perform before I start throwing parts at it almost at random? I would appreciate your thoughts.

 

[yesterdaysyouth]

Re: Fuel Delivery Problem 9.9Hp Evinrude 1976

sounds like fuel pump issues, since gas is more dense when it's colder....

 

[kenmyfam]

Re: Fuel Delivery Problem 9.9Hp Evinrude 1976

Sounds like the fuel pump may be failing.

 

[OptsyEagle]

Re: Fuel Delivery Problem 9.9Hp Evinrude 1976

Anyway to check the fuel pump or should I just replace it?

 

[kenmyfam]

Re: Fuel Delivery Problem 9.9Hp Evinrude 1976

Put the muffs on or run it in water.
Remove pump to carb hose at the pump end.
Remove plugs.
Put a temp hose from the pump outlet to a container.
Crank the motor and watch the output.
Post back what you find.

 

[OptsyEagle]

Re: Fuel Delivery Problem 9.9Hp Evinrude 1976

I will give that test a try. The motor is currently on my boat right now but I should be able to run that test that you suggest with it in the lake water. Will the test pick up the problem if it is intermittent? Do I need to wait until the problem re-appears or should it show itself in this type of test?

Also, is it possible that the fuel line or primer bulb or vent hole could be causing this type of motor behavior? I know the vent was full open.

 

[Solittle]

Re: Fuel Delivery Problem 9.9Hp Evinrude 1976

A wild shot - - replace the primer bulb.

 

[Rick.]

Re: Fuel Delivery Problem 9.9Hp Evinrude 1976

Many things are possible. The most likely scenario would be the pump. You really threw a wrench into the mix by telling us the time of day thing. That just isn't normal. If your tank wasn't vented properly then the heat of the day could be causing your tank pressure to act as the fuel pump for a short time. With a vented tank it wouldn't. Best of luck. Rick.

 

[OptsyEagle]

Re: Fuel Delivery Problem 9.9Hp Evinrude 1976

Thanks for all the advice. I talked to my dealer about parts and prices. They want about $100 for a new fuel pump, but only $17.00 for a rebuild kit. $17 seems reasonable and won't kill me even if it doesn't resolve the problem, so I think I will go that route. After 35 years I am sure the pump won't mind some new parts.

Any trick or tips in rebuilding these things?

 

[mikesea]

Re: Fuel Delivery Problem 9.9Hp Evinrude 1976

pay attention to how the parts come out,I agree with the 35 yr old pump needing service

 

[Rick.]

Re: Fuel Delivery Problem 9.9Hp Evinrude 1976

There are good instructions here. Be very careful with the tiny springs. Rick.

http://www.sschapterpsa.com/ramblings/Rebuilding_fuelpump.htm