Volvo Penta 454 engine trouble

[RickKennedy]

I hope someone knows something. I've been trying everything for a few weeks now.

my Volvo runs great for about 15 minutes and then runs really really rough.

I hooked up a spare fuel tank to eliminate fuel quality and restriction.
Fuel pressure checks out.
Hooked up another coil.
Changed the spark plugs, cap and rotor and module
Rebuilt the Carb
Puzzling how it runs great for about 15 minutes with all the above checking out.
The motor is on a 1996 26' Albemarle - single 7.4 GL 300 Horse Volvo Penta jackshaft

 

[duo_prop_dad]

Maybe an electrical connection?

Try wiggling wires while running......

How many hours?

Timing chain worn out?

John

 

[RickKennedy]

timing chain is ruled out...thanks...

seems like I need to look at the electrical.

working on it this weekend.

Thanks, Rick