Yanmar 3GM starting problem.

[gilesfordcrush]

I am suffering from an intermittent starting problem on my Yanmar 3GM (Moody 30). Pushing the starter button will fail to turn the engine over about 75% of the time. The other 25% of the time the engine will turn over and fire instantly. I am pretty certain this is not a battery problem, but is most likely a well known issue of insufficient current getting to the starter motor solenoid. My main reason for ruling out the batteries is that on every occasion that the engine has failed to start, I have managed to get it starting shortly afterwards, with no additional power, and it turns over quickly and fires immediately.

There are many stories on internet forums about this issue. It would appear that the accepted fix for this involved two approaches. The first is to simply ensure that all electrical connections are good, clean, and making solid electrical connections. The second is to add a simple automotive 30A (or thereabouts) relay that takes high current from the starter motor wiring directly onto the solenoid, switched using the existing bush button circuit.

The symptoms I have are that once the key is turned (and the alarm sounds) and on pushing the starter button there is an audible click, the alarm stops (presumably as all the current is being drained) and the engine does not start. If the button is released the alarm may start again, or once the key is turned to off and on again the alarm will start, and another start attempt can be made - with a chance of success.

I'd be very interested to hear from anyone who has experienced this kind of problem, and what approach they took to resolve it.

Thanks, Giles

 

[earlybird]

The click suggests that the starter relay is pulling in. Might though be voltage drop in the cabling to the switch. Isn't there a fuse hidden somewhere in the Yanmar loom that can cause problems?
Have you checked the battery connections including the earth connection back to the engine?
Edit; Changed relay to fuse!! must pay more attention.

 

[lw395]

The first thing to do is to see if a good 12V is getting to the control terminal on the solenoid.

 

[gilesfordcrush]

I started to clean up the connections to the starter from the battery last night. They were not the worst connections I've seen, but certainly needed improving. The positive cable to the starter comes from the master selector switch, and although those connections look ok, I'm going to remove and clean them up this evening. The connection of both cables to the starter motor and to the solenoid look ok too, but again, I'll be removing and cleaning them up too.

I suppose that that as earlybird suggests, a click means the starter is engaging, and that not enough juice is getting to the starter motor.

The problem with intermittent problems is that they are intermittent! However, with a 75% failure rate it should be pretty easy to spot if I'm making improvements! I will be using contralube gel on the connections,

 

[Bilgediver]

Start by checking the battery negative connection to the engine.. Clean all components at both ends. One easy way to check this is to use a jump lead between battery negative and a good point on the engine at times when the failure is occurring. If the engine starts as normal then bobs your uncle.

 

[maxi77]

Could be the solenoid contacts. A common problem on some engines. You can get replacement contacts for some. The intermittence comes from partial wear on the contacts which can move so sometimes you hit good but sometimes not.

 

[awol]

If access is reasonable, shorting the two big solenoid terminals with a spanner should demonstrate whether it is the solenoid or not. There will be sparks and, while it has never happened to me, it is claimed that you can weld the spanner to a terminal.

 

[SailSouth]

I had this problem ever since buying my boat with a 2GM, I thought I had checked all the connections, earth lead, etc over the years but the problem as you describe continued.

Having removed the engine last winter for a spruce up of the engine bay I found that there was a second earthing point (black cable with ring-terminal) onto the bracket that holds the gear selector cable. The cable goes into the wiring loom at around the same place as the white (I think) starter power cable. Make sure you clean this secondary earth connection and refit with Vasaline because it as completely fixed the problem on my boat.

Doesn't hurt to pull apart, check and remake all the block multi-connectors in the loom as well in case they have become damp.

Hope this helps, completely solved it for me without needing to fit a relay as some have done.

 

[SailSouth]

I had this problem ever since buying a boat with a 2GM, I thought I had checked all the connections, earth lead, etc over the years but the problem as you describe continued.

Having removed the engine last winter for a spruce up of the engine bay I found that there was a second earthing point (black cable with ring-terminal) onto the bracket that holds the gear selector cable. The cable goes into the wiring loom at around the same place as the white (I think) starter power cable. Make sure you clean this secondary earth connection and refit with Vasaline because it as completely fixed the problem on my boat.

Doesn't hurt to pull apart, check and remake all the block multi-connectors in the loom as well in case they have become damp.

Hope this helps, completely solved it for me without needing to fit a relay as some have done.

 

[Spyro]

I think everyone with a GM series has had this problem. I was putting up with it as it was happening about 1 in 10 times but this year it was getting worse. A few weeks ago I removed and cleaned all connections between and including the start button and the solenoid and the ignition key switch. There were quite a few also the main 30 amp fuse holder. a small bullet like connector, 2 big wiring loom plug and sockets and the terminals on the solenoid. It has been fine since doing all that so keeping my fingers crossed. I also noticed when testing that there is a variable resistance on the key switch depending on how I hold or move the key so that might be on it's way out. I have a jumper cable made up to connect directly from the +ve on the battery to the solenoid if I ever get really stuck.

 

[rudolph_hart]

I think everyone with a GM series has had this problem. I was putting up with it as it was happening about 1 in 10 times but this year it was getting worse. A few weeks ago I removed and cleaned all connections between and including the start button and the solenoid and the ignition key switch. There were quite a few also the main 30 amp fuse holder. a small bullet like connector, 2 big wiring loom plug and sockets and the terminals on the solenoid. It has been fine since doing all that so keeping my fingers crossed. I also noticed when testing that there is a variable resistance on the key switch depending on how I hold or move the key so that might be on it's way out. I have a jumper cable made up to connect directly from the +ve on the battery to the solenoid if I ever get really stuck.

+1.

Go over every single connection with a fine tooth comb. Mine turned out to be a loose connection to the Yanmar switch panel. Some people also fit an extra relay in the starting circuit. Mine had one fitted before I bought her.

 

[DownWest]

The 1GM10 in the friend's boat went from starting every time, but only after several revs, to mostly not responding. Pulled the starter and found it was chocker with greasy effluent and the commutator was black.
Clean it all up and found the brushes were being limited in their travel by the connecting wires bottoming in the slots in the side of the holders. So, essentially the brushes were worn out. Cleaning out gave them a slight new lease of life, and now it starts much quicker, couple of turns. Need to source new brushes quickly..... (not so easy) Likely try a decent auto electric place.

The panel had multiple bulb failures and ,as the bulbs are soldered into the holders, we replaced the lot. Probably still have duff connections in the loom, as the horn only sounds very occasionally.

Makes one want a Seagull hanging off the transom )

 

[bikedaft]

i checked all connections, took out + checked starter etc - no difference

left if for now a year - never had it again?

which is slightly worrying as i've no idea whay its better/what was causing it

 

[Javelin]

I nailed my issue down to the starter relay at the back of the engine.
The hassle and grief I went through to get to that point, I try not to remember as it was painful, not mention expensive in changing parts that didn't need changing.

 

[Spyro]

If you think it might be a wiring or connection problem you can replace the wire from the starter switch to the solenoid directly and do away with any connections. You will still have the ignition and large 30amp fuse and holder in the starting cct though. Has anyone replaced the ignition key switch and starter button with a combined starter and ignition switch? I was thinking about doing that.

 

[gilesfordcrush]

I carefully cleaned up all the electrical connections last night, and all would appear to be well. The modification of adding a relay is something I will keep in mind, along with possibly having the starter motors re-conditioned. The problem with an intermittent problem that might have gone away, is waiting for it to fail again so I can tap the starter and see if it fixes it!

 

[vyv_cox]

If you think it might be a wiring or connection problem you can replace the wire from the starter switch to the solenoid directly and do away with any connections. You will still have the ignition and large 30amp fuse and holder in the starting cct though. Has anyone replaced the ignition key switch and starter button with a combined starter and ignition switch? I was thinking about doing that.

As so many others have reported, I had exactly the same problem. On my 3GM installation there were four connectors in the wiring between switch and solenoid. Cleaning these up brought about some improvement for a time but not 100%. I replaced the whole lot with a single wire that has totally overcome the problem.