3126 shutdown

BobBDA again still trying to resolve port eng. shutdown. Replaced starboard alternator, replaced port eng. shutdown selinoid. Boat is wired with Starboard battery and alternator to run engines. Port batt. and alternator run house accessories. Both alternators putting out 14.3+ 

Using crossover for both battery banks engine will shut down after 20 / 30 min. Not using crossover will take 60 / 90 min. Starboard eng. always shuts down just Port is issue. Engines are fitted with intake heaters and draw current for several min. Pressing stop switch on Port eng. increases voltage on meter but continues to run. Batteries on Starboard are 4 years old interstate 1000 ch 12V. Sealed.

Selinoid is new ( old unit had same issue) distance from Stb. Battery's to Port selinoid approx 15 ft.

Selinoid is 3 wire (start, stop, ground) start & ground # 12 wire, stop #14 wire original cat wiring. (yellow red stripe)

Issue started 14 months ago previous alternator would go to -6 with heaters on new alternator at +4.

Will check batterie's and helm wires this week.

Any advise would help, Bob