Evinrude 18 hp that kills

[Dersu]

I have a late 1960s Evinrude 18 hp. It starts fine and runs fine most of the time. Periodically, however, it kills when it is running, even when running at high rpms. Once it kills, it will restart, but then it kills again like it is not getting fuel. The only way to keep it running when it is in the mood to kill is to squeeze the primer ball on the fuel line when it wants to kill. In the past when the motor would start to act up like this the problem would last for a few starts and then go away for awhile. This weekend it killed after running well for about 1/2 hour. After it killed once, it would not stay running without squeezing the primer ball. Any ideas on what the problem is and how I can fix it?

 

[RangerBob]

Re: Evinrude 18 hp that kills

I would start by replacing fuel line and primer bulb. Also, check to make sure the gas tank is venting properly. After that I would suggest a carb cleaning.
Mark

 

[lindy46]

Re: Evinrude 18 hp that kills

If after doing the above it still does not run right, check fuel pump.

 

[Dersu]

Re: Evinrude 18 hp that kills

How do I know if the gas tank is venting properly?

 

[lindy46]

Re: Evinrude 18 hp that kills

The single line tanks are self-venting, but you can try cracking the cap open and see if it stays running.

 

[pmillar]

Re: Evinrude 18 hp that kills

If your tank isn't venting you should hear a slight whoosh of air when you open the tank after running it for a bit. As the gas is pulled from the tank while operating your motor, a vacuum is created in the tank if there's no venting. Eventually, the vacuum will result in a starved condition as it overcomes the vacuum created by the fuel pump... meaning insufficient gas to your motor.

This is pretty common in motorcycles - which I am much more familiar with than boats :

 

[outlaw241]

Re: Evinrude 18 hp that kills

i would also look in to checking the compression, i believe your fuel pump works off engine compression an it could be dropping compression on that cylinder after it heats up.