I have a 1968 Evinrude 18 hp. I few squeezes of the primer ball firms up the ball. The motor starts fine and runs for a minute or so then starts to sputter and finally kills. Before it sputters and kills it usually revs a little. It used to only do this intermittently, now it does it every time. I can keep it running by squeezing the primer bulb when it wants to kill. The primer ball is hard when I start the motor, but softens some by the time the motor kills.
Here is what I have tried so far. I attached a new fuel line with a new ball and hardware. I also changed the hardware that attaches the fuel line to tank. The tank vent is open. I also tried it with the cap off the tank. I removed and cleaned the screen on the fuel pump even though it really wasn?t dirty. The motor is on a Jon boat, so the gas tank is not much lower than the motor. In any event, I tried running the motor with the gas tank about two feet higher than the motor. None of these changes made any difference.
One thing I have not done yet is fill the gas tank to the top. It is just below half full. The problem did not occur until the tank drained down to about half, but I really cannot say whether that is a coincidence or evidence.
I?m generally ignorant in these matters, but it seems to me that it is either the fuel pump or the carburetor. I?m leaning toward the fuel pump. Is there any way to definitively diagnose the problem? Where do I go from here? I would hate the go to the trouble of rebuilding the carburetor if it?s the fuel pump and vice versa.
Any advice will be greatly appreciated.
Here is what I have tried so far. I attached a new fuel line with a new ball and hardware. I also changed the hardware that attaches the fuel line to tank. The tank vent is open. I also tried it with the cap off the tank. I removed and cleaned the screen on the fuel pump even though it really wasn?t dirty. The motor is on a Jon boat, so the gas tank is not much lower than the motor. In any event, I tried running the motor with the gas tank about two feet higher than the motor. None of these changes made any difference.
One thing I have not done yet is fill the gas tank to the top. It is just below half full. The problem did not occur until the tank drained down to about half, but I really cannot say whether that is a coincidence or evidence.
I?m generally ignorant in these matters, but it seems to me that it is either the fuel pump or the carburetor. I?m leaning toward the fuel pump. Is there any way to definitively diagnose the problem? Where do I go from here? I would hate the go to the trouble of rebuilding the carburetor if it?s the fuel pump and vice versa.
Any advice will be greatly appreciated.
