Yanmar 3GM30F - Starter WOES

[Coolruns]

Setting the stage:
- Early season, new battery 100Ah, 12V, 690 CCA
- Operated 8 or 9 sails since install, no trouble
- Two weeks ago, I had a failed pinhole leak in the lubrication oil tubing that resulted in complete loss of oil. Fortunately, I was in the fairway and just quickly made the slip and shutdown. Fixed this the following weekend. Motored out no problems. This was two weeks ago.
- Today, visited the boat. Decided to change the fuel filter and re-tension the belts. Quickly did this in less than an hour. Bled the system of air.
- Went to start the engine, key on, ignition alarm came on like normal, pressed the start button. Nothing. Would not even turn over.
- Started checking voltages everywhere. Starting with battery. 13.2V, seemed fine. Went to key switch, roughly the same about 13V. Went to the Start button roughly 13V on primary, but dropped to about 3-4V on output.
- Thought maybe I had a bad Start switch, so I changed it out with my spare. Checking continuity, both switches were ok. After installing new switch with no positive result I started looking at the starter.
- Went to the starter and found the white wire had rubbed raw (from vibration over the years) and was grounded. Fixed this. Now had about 9V at the terminal of the starter. Main voltage at the positive terminal of the starter was 13.2V. Negative terminal seemed fine.
- Double checked tightness of all terminals, cleaned wiring, just in case I had an external ground somewhere.
- I even tried pulling the battery and charging it for about an hour, just in case it was the battery.

Things I did not try:
1. Pulling the starter OFF the engine and see if it turns over.
2. Disconnecting white wire from starter and see if I had a full 13V.

Any suggestions? Experiences?

Appreciate the thoughts.

Best Regards,
DJ

[Arthur Garfield]

Try jumping across starter solinoid power post to white wire post with screwdriver.
Key on if you want to start engine. I suspect solinoid switch went bad from short of "white wire".

[CptLawrence]

Maybe flipping the decompression levers will help, also try grounding the starter with a jumper, sometimes just taking the bolts out and cleaning them helps.

[laika]

Agree with Arthur..the solenoid wire issue seems fairly common with the 3gms.

I resolved the issue on mine by running a new #10 wire from the start push button straight to the solenoid. It's the small white wire on the side terminal of the solenoid. Previously I had the solenoid "click" with no engagement of the starter. It usually took a handful of button pushes before the starter would go, if it would go at all.

Incidentally, all the wiring on my 2004 3gm30f was non-tinned and in terrible shape after 10 years, so I ended up re-wiring the entire thing.

[Ex-Calif]

A quick check to see if you have a failed battery.

- Turn on VHF. Meter the battery. Hit the transmit button. Look for voltage drop.
- Turn off VHF.
- Turn on engine master panel. Monitor the alarm (you already reported this) - hit the starter. If you get no solenoid click and the alarm/panel/light does not "dim" or alarm change frequency or get any voltage drop at the battery (still metered). You may have a failed solenoid.

It is not highly recommended but you can jumper the main starter terminal to ground with a BAS (big assed screwdriver) - if the motor turns replace the solenoid.

It is not clear to me if the white wire is the solenoid wire. If so it should have only leaked current to ground when the start switch was engaged.

Check the circuit for a start relay or start fuse. If the white wire was shorted and you engaged the solenoid that surely would have popped any fuse in the start solenoid circuit.

[NoTies]

OK, you're on the right track but a bit off to the side. Measure the voltage at the starter (large terminal with a few wires possibly on it) and ground on the engine block. Measure the voltage again with someone operating the starter. If it drops to 3-4 volts it is nothing to do with the starter, switch, fuses, or anything else. You have a voltage drop through your main wire to the starter, battery isolation switch or even a bad battery. Determine which by progressivley working back from the starter to the battery. When the voltage suddenly returns to 12V with somebody turning the key to start will tell you where the problem lies.
If, under the inital test the voltage stays the same, try measuring the voltage at the starter as before but put your negative lead back direct to the battery negative post (not terminal). If the voltage drops then you have a grounding problem.
Google Jimmy Cornell's start voltage diagnosis, he has another method and is a whole lot better at explaining things than me.

[Coolruns]

Thanks to All.

I wish I was at the boat tonight and I would try this.

laika and NoTies, I think it might be the wire between the switch and the solenoid. NoTies, I did notice a large voltage drop when my wife hit the button while I was measuring the voltage at the terminals of the starter. I was surprised that I was only getting about 8 volts at that terminal (representing about 5 volts, since I measured 13.2 at the switch terminals). This seemed excessive to me. This was what led me to search for a ground. Which I thought I found. I'm thinking I only found PART of the grounded wiring.

I will be back at the boat hopefully Friday, but certainly Saturday.

I'll report back once I determine what is going on.

Appreciate all the help.

-DJ

[Coolruns]

ExCalif

I'll attempt the voltage check with the VHF as suggested. Question: Does this work the same if you have a segregated House Batt System and Motor System?

The white wire I have been referencing runs between the Start Switch at the Yanmar panel in the cockpit down to the solenoid. Of course with nearly 5,000 miles on my motor its not so "white" anymore. LOL.

I did double check the fuses on that side of the engine. They ohmed out fine. I know sometimes the ohmeter lies though. I have experienced that before.

Appreciate the help.

Best Regards,
DJ

[Arthur Garfield]

Cool,if you jump with scewdriver across from power post to white wire post
and starter engages this'll tell you starter good and "white wire" from switch may be the fault.

[Ex-Calif]

Originally Posted by Coolruns

ExCalif

I'll attempt the voltage check with the VHF as suggested. Question: Does this work the same if you have a segregated House Batt System and Motor System?

The white wire I have been referencing runs between the Start Switch at the Yanmar panel in the cockpit down to the solenoid. Of course with nearly 5,000 miles on my motor its not so "white" anymore. LOL.

I did double check the fuses on that side of the engine. They ohmed out fine. I know sometimes the ohmeter lies though. I have experienced that before.

Appreciate the help.

Best Regards,
DJ

It will depend how the battery switch is wired. If the battery switch can parallel in the house battery, or the house battery can supply the starter by itself - you can simply try to start the engine with the house bank.

If the house can start the engine it would eliminate the solenoid/start circuit from suspicion.

For doing the VHF check - the start battery would have to be wired in (from the batt) switch to supply house loads.

[Coolruns]

UPDATE:

Thanks to all for the information and suggestions.

It turned out to be the starter. Bought an aftermarket unit from local marine supply.

It took about an hour yesterday morning to replace. I primed the fuel system and bled the air one final time. She cranked up like a dream. I believe the starter has been "weak" for quite a while. The new starter cranks up very swiftly. So fast that I had to quickly release the start button.

So we are back in business.

Fair winds and following seas,
DJ
S/V Starlight