2004 Hunter 33 with Yanmar 3YM30 won't start....occasionally

[niner_gang]

Recently went out, turned off shore power, switched to battery #1, just given the date, and nothing...radios and instruments were on, and voltmeter on the DC panel read ~12.75 volts for both batteries...I turned to Both batteries, and it fired right up..

Figured it was a weak battery, motored for 45min or so, shut off the engine and sailed for a few hours. Left batteries on both, went to start engine, and again, nothing..engine wouldnt turnover, and no obvious noises. Switched back and forth a few times, reset the DC breaker on the battery selector, and maybe on the 4th time, it started...

Got back to the dock, turned on shore power and charger, and both batteries read just over 14 volts, so seems charger is working properly.

It seems clear it's not a battery issue, but have no clue where to start...any help is appreciated. Maybe a loose/weak connection between the batteries and the starter or even the ignition?

 

[twalker H260]

Might want to check the pressure of the engine compartment fire extinguisher. If it’s low it could prevent the engine starting. I believe you can press the engine alarm button to temporarily start the motor.
p7.9 in the manual.

https://sbo.sailboatowners.com/downloads/Hunter_33_914140.pdf

 

[dlochner]

It seems clear it's not a battery issue, but have no clue where to start...any help is appreciated. Maybe a loose/weak connection between the batteries and the starter or even the ignition?

How old are the batteries? What kind of batteries, FLA, AGM? What kind of alternator do you have? What kind of charger do you have?

Voltage is not a good indicator of a battery's state of health. 9 AAA batteries can be connected in series will read 13v on a voltmeter.

The symptoms you describe are very suggestive of old batteries that can no longer hold a charge.

 

[Bob S]

Could have a loose or corroded negative, ground wire. Check all the connections.

 

[DougM]

This seems to be a common problem. While it could be the batteries, the culprit often turns out to be the white wire that runs from the starter button to the starter solenoid. The wire is undersized, long and has intermediate connections.

The easier fix is to abandon the original white wire, install a new heavier gauge wire using the same color code and home run it from the switch to the solenoid. Also, it would pay. to clean and tighten other connections in the system to maintain good contact.

 

[shemandr]

My Yanmar used to do the same thing. DougM is right. The problem often is the undersized wire from the start button. This is a common problem because of the stupid wiring harness Yanmar uses. It's easy to test as Doug says. Run a heavier gage wire don't even bother to route it for diagnostic purposes. If the engine starts regularly run a permanent version. I used a relay but I think the wire is easier. If you search the forums you'll find numerous posts on this subject. I bought a new AGM 4D battery before I learned this. OUCH!

 

[dlochner]

The problem with the undersized wire is compounded by a weak battery. Part of the issue with the white wire is the length of the wire and voltage loss along the wire. The underlying issue is inadequate current to close the solenoid to engage the starter. When the battery capacity is weak, not the voltage level, the voltage drops quickly and the solenoid won't close.

If the batteries are new and have been properly charged and are at or near full capacity then the white wire issue is the problem. If the batteries are older or have been improperly charged then the problem is the battery
and most likely the white wire issue.

 

[higgs]

In addition to above suggestions, I would check all connections at the starter making sure they are clean and tight. Next time it won't turn over try a light taps on the starter with a hammer while someone else tries to crank the engine. If that gets it started, then your problem is probably the starter solenoid or dirty armature. A new starter on a Yanmar is usually around $1000, but starters can be rebuilt at an automotive starter shop.

 

[dlochner]

A new starter on a Yanmar is usually around $1000, but starters can be rebuilt at an automotive starter shop.

After market starters can be had for considerably less. And most starters can be rebuilt as you note.

 

[niner_gang]

The problem with the undersized wire is compounded by a weak battery. Part of the issue with the white wire is the length of the wire and voltage loss along the wire. The underlying issue is inadequate current to close the solenoid to engage the starter. When the battery capacity is weak, not the voltage level, the voltage drops quickly and the solenoid won't close.

If the batteries are new and have been properly charged and are at or near full capacity then the white wire issue is the problem. If the batteries are older or have been improperly charged then the problem is the battery
and most likely the white wire issue.

Thanks alot. It's hard to tell, given the previous owner spraypainted everything grey, but this is the starter solenoid, correct? You can see the small white wire coming down out of the rubber covering near the bottom of the pic. Thanks.

 

[MitchM]

my 3 boats had yans. (1GM10, 2GM20F, 3JH4e.) all 3 had start switches w key lock in the cockpit. after about 10 years, each of them was starting to be hard start though batteries seemed good. some voltage and amp measurements showed serious voltage drop due to long old wire runs from the engine starter system up to switch, some across the switch then back down. measuring voltage at the battery might show good volts there but there can be serious amp drop in the switch system . a good fix recommended by mack boring yanmar east coast distributor was to install a second 'momentary' button start switch very near the engine compartment. so the run from battery + to switch to starter was a foot, not 10 feet and back. the momentary switch was very handy for starting the engine when doing diagnostic work (instead of jumping on top to the refrigerator to s cramble into the cockpit to start the engine w the key switch then jumping back in to cabin w/o falling on top of the engine.)

 

[dlochner]

Thanks alot. It's hard to tell, given the previous owner spraypainted everything grey, but this is the starter solenoid, correct? You can see the small white wire coming down out of the rubber covering near the bottom of the pic. Thanks.

The PO was covering the rust and sprayed it Yanmar Gray.

Typically the solenoid is near the starter or attached to the starter, but I'm not familiar with the 3YM30.

The white wire goes from the postive connection on the starter to the key and then back to the solenoid. It is this long run that cause the problem. When I replaced mine, I removed the wire from the starter to the ket and powered the circuit from the battery, this cut the wire run in half.

 

[shemandr]

Always look under the fresh paint and duct tape.

 

[Dan_Y]

On my '08 h36 3YM30 the power at the key gets sent to that relay in your photo. Engaging that relay sends power to the solenoid on the starter. The control wire from the start switch to the relay in the photo is smaller gage than the wire used to/from the relay contacts to the starter solenoid. There are 4 connections on that relay. Two are barrel connectors for the key switch (coil power and ground) and two are ring terminals for the heavier wires that send power to the starter solenoid. Check/clean all connections. One of the ring terminals picks up power from the starter cable on the starter solenoid and the other ring terminal is a white wire that connects to the end of the starter solenoid via a 1/4" spade connector. Clean that connection - but you may need to remove the alternator to do so . mine had lots of rust on it due to a raw water pump shaft leak that was untreated by the PO. I put a double connector there to send the start signal to my BSS ACR so it separates the house and start batteries so starting current is not drawn from the house battery through the acr while cranking. Amazing that it's not a screw terminal for the white wire on the solenoid.

Reference the starting relay in figure 9 of the manual. This is a great figure to understand and will give you more confidence to troubleshoot engine electrical problems. You can see one side of the starting relay goes to the solenoid on top of the starter. People have added this starting relay in the past (not to be confused with the starter solenoid). It appears your engine has the starter relay. cleaning the connections on the key switch is useful as well. In this case, the starter switch contacts may not be rated to carry the starter solenoid current if you wire directly from the key switch to the solenoid. Finally, check the two harness extension connections near the rear of the starter motor area that come from the instrument panel. One connector has 3 larger wires and the other has about 8 smaller gauge wires. Clean and remate. Cutting those two connectors off and replacing them with individual waterproof butt splices is on my to do list, assuming there is sufficient slack to do it.
Dan

 

[Ken13559]

Usually is due to bad contacts in the two cable loom connectors. Open up and clean the spades, spray contact cleaner. That usually does the trick.
On a side, I wired an alternate emergency start switch at nav table for just in case.

Ken Y

 

[FastOlson]

Occam's Razor.... should be invoked before doing some (apparent) overthinking!

First, remove and clean up ALL positive and negative wire connections. Sandpaper each lug, wipe clean, and treat with some appropriate waterproofing.

Starter motors are difficult to R&R on most small diesels, and batteries are heavy. Best to first make sure that those lazy 12 volt electrons are free to travel out n back.

 

[shemandr]

Occam's Razor: OK I had to look that one up. But I never did take Philosophy. I was good enough at confusing myself. No reason to go pro. But I like it better than Hickam's Dictum.