Common rail Diesel issues

[sailon46]

I have two 45 yanmars common rail in a leopard 2019 45. The starboard engine gave some issue upon delivery last June from Moorings Tortolla. It ended up been water in the tank maybe or cleaning various electrical contacts on the block. Sailed her to Curaçao for the hurricane season so now I am up in Cap Cana marina in DR. The port engine will not charge the starting battery which is bad for common rail because my understanding the ECU needs amps to work and pressurize the fuel. Also the fan for the engine compartment so fire up upon engine ignition. A direct wire from alternator positive to the start g battery positive took care of that maybe. Also the fan now has a switch and manually can turn on but you have to remember to turn it off. I am open for suggestions.

[purvisgs]

check grounds, acquire wiring diagram & ohm out any/all relevant circuits looking for high resistance, replace the harness or run new wires, hire a competent mechanic?

Originally Posted by sailon46

engine will not charge the starting battery

check alternator for ~14v or test alt per service manual , replace

[sailon46]

Alternator was recently replaced during the crossing from Curaçao to Puerto Real western PR it performed flawlessly keeping the battery fully operational. Thank you for your excellent advice. I’ll be at the boat the 31st of January and I will follow your directives. As far as competent mechanics so far anybody that tried it gave up.

[sailon46]

Hello in addition I want to ask the question that needs answering is that a failure of The ECU.
Thanx

[skipperpete]

Originally Posted by sailon46

Hello in addition I want to ask the question that needs answering is that a failure of The ECU.
Thanx

I’m interested to know.....what was the cause of the previous alternator failure? Was it replaced with an OEM part or was the original one repaired? You’re totally correct about the significance of a constant stable DC supply to your engine, the bulk high pressure fuel is supplied to the common rail by an engine driven pump but thats the end of the mechanical part of the system. The injectors are ENTIRELY reliant on electrical impulses to trigger the injection ( often multiple as the piston approaches TDC compression) at a point and volume ENTIRELY chosen by the CPU based on data from a group of sensors. Once in the not too distant past the start battery was there to do just that....start the engine. Gauges were capillary so the engine could run happily with no battery or alternator. That halcyon time has passed and the engine battery has assumed a critical role..... without DC your engine is as dead as KFC. I’m not sure if your alternator is controlled by the CPU, it definitely is for automotive applications for both EPA reasons and on my car I suspect for braking to maintain cruise control...and regen charging. Your current problem actually makes a case for installing a second start battery ready to be paralled in if the need arises..... probably not for near coastal but it could make sense for bluewater cruisers. As a not so young and still working diesel tech, I had to retrain on the various common rail and electronic fuel systems so I’m no stranger to the innate fragility of these engines ....but I keep away from em as much as possible and refuse to buy or steal the laptop diagnostics software given the fairly low numbers of cruising yachts with electronic engines.

[purvisgs]

https://lsm-diesel.dk/2012/yanmar/pd...JH45-CR_uk.pdf service manual pdf I am not sure if this is the same version 4JH45-CR you're talking about, but I had this saved from my bookmarks . Link = is the service manual, one way or another get the right manual , print out a hard copy , and study it etc



In a cat, once you have covered the basics to make sure nothing is shorted- you can (likely) just swap the known good ecu to test it, Or follow the diagnostic to test the ecu (starting with; probably, check the alarm codes / other codes etc).



also print the install manual, wiring diagram, and check/compare the install and label every wire .



Tools/DIY you just need: ANY dc multi meter ($10 up) or ~$60-100+ with a dc amp clamp function that might possibly be helpful for general dc boat use.



If the "recommended yanmar mechanic " in town fail, I'd try to find marine electronics guy , or even the experienced/licensed land based residential/off grid solar, alternative energy installer type business.


Your "cleaning engine connections might have fixed it" story sounds like (what is commonly) a ground problem, to clarify, wire brush & metal file to clean both sides of all terminals and contact points, (make sure to connect all ground points / DC negative--together and update/improve system for future reliability, specifically: connecting all grounds and large metal items on entire boat together & etc) plus replace any terminal or connector or wire if corroded or suspect, THEN check each suspect/related charging circuit for ohms/ resistance

[sailon46]

Thank you you have given me precious food for thought when I get down to Punta Cana and get to the boat. I’ll be busy filing gently all contacts in the port engine compartment.
Keep you posted what fish I catch in the engine room.
Ernie on the LoreMar

[Byrdman]

Originally Posted by sailon46

Alternator was recently replaced during the crossing from Curaçao to Puerto Real western PR it performed flawlessly keeping the battery fully operational. Thank you for your excellent advice. I’ll be at the boat the 31st of January and I will follow your directives. As far as competent mechanics so far anybody that tried it gave up.

Belt change. Check tension

[sailon46]

New belt installed tension ok alternator putting out 14.3v to the battery with a cable connecting positive post if alternator with posited post of battery .