Mercruiser 140 181 3.0 runs for a while then dies.

[JesterOMA75]

My oldest son and I bought a cheap boat over a year ago and have been working together to get her back to good. It is a 1986 Mecruiser with a 2 barrel mercruiser carb and EST ignition. We have made quite a few repairs including replacing the floor and recovering the seats. We are having an issue where the engine runs fine at around 3200 RPMs for 10-20 minutes then dies. After it dies it can be hard to start and can die again when you apply the throttle. We did rebuild the carb and replace the fuel lines and filters. We also replaced the plugs, plug wires, and cap and rotor. My question is i
A. a timing issue?
B. a fuel issue? float height/restriction/weak pump
C. a coil issue? Maybe the coil is getting hot?

 

[Scott Danforth]

My guess is plugged fuel vent. However could be plugged pickup or anti siphon

time to check fuel pressure

 

[JesterOMA75]

How do I check the anti-siphon? I had to replace all of the fuel lines the vent hose and the fill hose when I rebuilt it. I will see if I can blow through the vent and check if opening the fuel fill cap helps when it's out next. I have a feeling the fuel pump is very old, possibly original from 1986 judging by the matching paint to the engine block. Could the fuel pump just be giving out? Seems like an easy cheap test as well.

 

[JesterOMA75]

I also put on a generic fuel filter... Read somewhere that some are too restrictive. Does that sound plausible?