1996 Mercury 150 EFI start issue

[Dacrud]

Hi,

I'm having trouble with this motor starting. Starts and runs great with just ear muffs in the driveway, but under water it won't start. Also when I turn the key a quarter turn I don't hear the normal beep anymore, only about 50% of the time, but I still hear it priming.

When I put it in the water crank it tries but won't stay running for more than 1-2 seconds. Then sometimes it struggles and just spins and spins while I hold the key. Trimming it up out of the water allows it to start.

Any tips, anything would be appreciated. Thank you

 

[Faztbullet]

Check spark as sounds like running on one bank....no back pressure and it starts easier.

 

[Dacrud]

Thanks for the information, I will do the spark test.

I did notice yesterday on one of the spark plugs when I put new ones in that the black connector end that goes into the motor, not the spark plug, was very lose and it almost pulled right out. I don't know what that end is called but it's about as big around as a quarter and has a gold piece on the inside. I just pushed it back in.