Need HELP... Motor is cutting out
 

I have a 1991 Powerquest Enticer with twin 454 330hp motors. The Port side keeps cutting out at W.O.T. it looses power after about 4-5 seconds wide open.

Heres what I have done:
1. Rebuilt both carbs and switched side when I reinstalled.
2. Replaced Fuel pump on Port Side. Starts quicker but still cuts out.
3. Had it out tonight and thought I would check for arcing on spark plug wires. Found Port side coil wire would arc when grounded. Switched it with the STBD took it out, STBD is fine and PORT still cuts out.

Now the motors run great as long as you are not wide open.

Not sure where to go from here and I hate changing parts for no reason what so ever. Any suggestions would be great at this point.

Thanks in advance.

bump

Just went thru working all the snakes out of my rebuilts. You switched the carbs from side to side to confirm that carb rebuild is not the problem, correct? have all your gaskets under the carbs?(i had one sucking air and wasn't torqued on all four corners). You aren't bumping your rev limiter by chance? the rev limiter doesn't cut the ignition completely off. It eases out and will make you think something is wrong. Thats what my thunderbolt V's did on only one engine side. I am only familar with the TB V. Which ignition do you have?

Make sure all plug wires in proper firing order and boots are snugged. It has to be fuel or spark related as to what you are tracing now. the TB V ignition modules can become cracked with age and temperature, maybe check for that. Just ideas to look at that I have seen

Make sure you don't have a rubber fuel line on that motor that has gone soft and is collapsing on you. Did you swap coils or just coil wires? Pull the cap and make sure the inside isn't carbon-tracked around the terminals. While the cap is off, make sure the advance weights aren't all rusty and easily open out.

Good point. What RPM are you turning on that motor when it starts to cut out. Could be as easy as hitting the limiter.

fuel filter is another one that can impede fuel flow after the pump.

It sounds like a broken valve spring to m. Remove the valve covers to inspect.

Check the anti-siphon valves that go in the fuel tank pick up mine clogged up with junk a few years ago, and engine would run great up to about 4000k than start surge and fall back.

Does it happen at WOT at lower rpms too ? or at a certain rpm ?

Just trying to see if fuel issue when secondaries are open when engine trying to make most power or if it is at same rpm but not throttle position and more likely ignition / valvetrain.

Oh, and when you say 'cut out' does the engine die ? Start misfiring and losing hp ? Or no misfiring noises but losing hp ?