NO ONE HOME ON Cylinder #1 1973 Mercury 50hp thunderbolt 500

[Myfirstboat86]

1973 mercury 50hp model 500 inline 4cylinder. Dual carb. Took boat to a shop. Had the carbs done, upper crank seal, fuel lines all the way back, water impeller and timing adjusted. Cost $680. Get the boat back and take it out for first time and it starts right up, idles great, at wide open throttle it only makes 4000rpm and only goes 9.5mph. Took it back to mechanic. He says that no one is home in cylinder 1. At wide open throttle I can pull the plug wire off of cylinder 1 and the motor doesn't skip a beat. Sounds the same and continues to run with no change. I've tested spark and it's getting good spark. New plugs. Compression reading is 115psi. Mechanic says he thinks it has a scorn piston or a broken piston skirt. Is this a possibility? Like I said it starts right up idles and jumps right up to 4000rpm and 9.5mph. But that's all she's got. I've got a lot of time and money now invested in this engine and I don't know what else to do here. Any input or diagnosis would be greatly appreciated! Thank you!

 

[hemi rt]

Were the plugs replaced when all this work was done? Do you have a picture of the #1 plug and could you post it. Sounds like the cylinder isn't getting fuel.

 

[Myfirstboat86]

Won't let me post pics. Says file size is too big. Plugs are new. Plug #1 is dirty and wet. When I look in the rubber boot on plug wire for #1 I can see bare wires down inside the boot on plug end of plug wire. Check spark and it appears to be firing consistently.

 

[Myfirstboat86]

There we go.

 

[Faztbullet]

Fix the boot with spring and pop a new plug in it, if it still wont fire it likely has a reed problem....

 

[Myfirstboat86]

I don't understand what you mean by fix the boot with spring? I was just gonna order a new plug wire and see if that wakes her up, but more open to a cheap easy fix at this point. I understand you need to split the case to get to the reeds on this engine. What goes wrong with the reeds? Would A bad reed affect more than just cylinder1 with a dual carb system? Thank you for your reply.

 

[Faztbullet]

Here a link on how....
https://www.youtube.com/watch?v=8chc6cv2-_E
And heres the boot/spring......