Starting problem

There could be many reasons for this, head gasket, tappet clearance, bad valves, bad rings , old engine, diesel in the oil, poor batt, poor starter, bad earths, starter solenoid, air filter, etc etc etc

Put some oil in the cylinder see if that helps.

 

testing hard start

first does it lose fuel prime sitting?? if there are no glo plugs starting fluid in emergency only, not a fix, something changed, rings seated problem or fuel problem, compression test and leakdown test, then injector spray test, find out what has changed since ocean temp should keep engine at somewhere above 26 deg F,

 

fuel additives

it is not a good idea to add anything that will produce hard carbon residue, gasoline is not recommended, fuel stabilizer like redline or like is the only thing to go in tank.

 

Gasoline is a petroleum derivative as is deisel and as is methelated spirit and jet fuel all sold in little bottles with incredible claims to temp the Sunday afternoon mechanics

 

A simple measure of the voltage at the starter, as the engine is cranked cold , as well as a strobe tach reading while cranking would be helpful.

A compression reading on a warm engine , then with a bit of oil to help seal the rings would be worth the effort.

If these engines were not notorious for lousy cold starting , a simple restoration , battery , batt cables , starter brushes or a set of rings might be a better cure, than add ons.

KISS!

FF

 

Haven't read the whole thread.

Did you try adding another starter battery in parallel?

I'm not suggesting this as a solution, but as a diagnostic procedure.

If all goes well then you've either got a weak battery or excessive voltage drop through your system.

-Tom