74 merc 800 fuel isssues?

[kilroywashere1911]

I have a 74 merc 800 that when I got it it fired up and ran great, I put a jet on it and it's been up and down since.
Started getting hard to start had to feather the throttle to find the sweet spot, eventually started and ran fine then started losing power. Took to shop he went through carbs it was still doing it. He suggested I clean out the cooling chambers in case I had impeller chunks- which I did, and there was. Got it all back together but before I tested it, I ran the gas tank to the front of the boat and installed a posi flo fuel pump. Put it in the water and tried starting it. It eventually fired when I found the sweet spot on the throttle but if I throttled up or down a fraction of an inch it would sputter out no bringing it back. Are there any suggestions as to what might be causing this? New fuel, 50:1 mix fuel cap completely open to vent. So far I'm spending more time fixing this outboard than getting to play on it.

 

[PatinIdaho]

What is the compression of all the cylinder's?

 

[kilroywashere1911]

Compression is at 120, I suppose I should check it again after having the exhaust manifold and baffle plate off. Could that problem be indicative of air leaking into the fuel line?

 

[kilroywashere1911]

I disconnected the fuel line where it enters the motor and placed it into a glass bottle when I turned the fuel pump on the gas seemed pretty "aerated" I will post a link when it's done uploading to YouTube

 

[kilroywashere1911]

Posi flo fuel pump: https://youtu.be/8b40XxGWSlI

 

[kilroywashere1911]

I went through and checked every fuel connection from the tank to the motor. Fuel flow is much smoother. Put it in the water and it will only start and run with full choke engaged- any ideas?