WOT on startup

[Tony1173]

Mercruiser 4cyl, 3 L engine. Brand new carb. On start up with shifter in neutral actually shift cable not even hooked up, my engine screams at full throttle. Throttle butterflies are closed. Is this a vacuum leak?
View attachment 20210609_143302.mp4

 

[Texasmark]

Amazing. How do you get enough CFM into the cylinders to do that.....not through a 5/16" vacuum hose.....650 CFM? No Sir.

 

[Faztbullet]

Take the throttle cable off and make sure throttle plates closed. Did you do any carb work as there are several types of base gaskets that will cause air leak under TP's

 

[Tony1173]

Yes I swapped out the old carburetor for a rebuilt one. And used the gasket it came with, which seemed to fit fine.

 

[Tony1173]

Amazing. How do you get enough CFM into the cylinders to do that.....not through a 5/16" vacuum hose.....650 CFM? No Sir.

Not sure I understand what you are saying