1993 Evinrude 120 V4

[bartmn5]

My 120 horse Evinrude starts with out much prblem, but I'm experiencing a couple things.
1. When throttling up it sometimes seems sluggish and then will pop
2. Last time out wouldn't keep running unless I continually pumped the gas bulb as it would suck the gas out of the bulb and then die until pumped up again.
3. I also have surges where it will run strong, then lose power to where it nearly dies and then will take off again. After a few times (usually any way) of doing this it seems to run good and strong. Any ideas on what could cause this?

Thank you,

bart

 

[ezeke]

Re: 1993 Evinrude 120 V4

Could be a lot of different problems but lets look at the fuel system first.

Is the primer bulb collapsing or just getting soft?

Are you using a full-sized water separating fuel filter?

Is the fuel fresh?

Do you have a built-in tank?

Have you tested the ant-siphon valve?

Are you using the OMS as designed or pre-mixing?

Have you checked for air leaks?

 

[bartmn5]

Re: 1993 Evinrude 120 V4

Thank you ezeke,

I have a few places to start.

 

[bartmn5]

Re: 1993 Evinrude 120 V4

I replied too quickly. Fuel gets sucked out of bulb, the bulb gets soft, and motor naturally runs out of fuel. I do have a built in fiber glass tank. I am using the oil injection OMS?

Man I'm going to like this site. What a wealth of knowledge here!

 

[ezeke]

Re: 1993 Evinrude 120 V4

The bulb should get soft while running but should not collapse. If the bulb collapses you have a fuel restriction before the fuel pump.

Are you confident that the tank is fiberglass and not plastic?

 

[bartmn5]

Re: 1993 Evinrude 120 V4

Now that you ask, no, I'm not sure.

 

[ezeke]

Re: 1993 Evinrude 120 V4

Ethanol breaks down fiberglass resin, causes multiple problems. Many boat manufacturers used plastic tanks that have not had such problems.

Ethanol use has made it a practical necessity to have a full-sized water separating fuel filter and to dump it fairly frequently. When water separates in the fuel tank, it goes to the bottom of the tank where the fuel pickup is and that water is the first thing pulled into your engine.

 

[bartmn5]

Re: 1993 Evinrude 120 V4

Thanks again. So I should quit using ethanol? How do I check the anti siphon valve? I assume it is in the tank. Sorry, but I am an out board dummy.

 

[ezeke]

Re: 1993 Evinrude 120 V4

Noone is expecting anyone to stop using ethanol.

The anti-siphon valve is in the outgoing fitting at the top of most built-in fuel tanks. It's there because USCG regs require it when any part of the fuel system is lower than the top of the tank.

The valve usually consists of a spring loaded steel ball. The valves have a tendency to clog or stick over time, plus, the older ones were not designed for ethanol use.

 

[bartmn5]

Re: 1993 Evinrude 120 V4

Thanks again, and I'm not going to beat this to death. You have given me some great advice. My boat is a 1990 Javelin. What are your thoughts on the siphon valve for this boat?

 

[ezeke]

Re: 1993 Evinrude 120 V4

Look your fuel system over carefully and decide if any of the system is lower than the tank. If it is, clean the anti-siphon valve; if not, get rid of the ball and spring.

I think that your tank would be plastic, not fiberglass.