Intermittent problem starting engine...

[John 32i]

At the start of last season we had an issue with our previously very reliable Yanmar 3YM20 – when turning the ignition key the warning alarm sounded but absolutely nothing happened – completely dead; generally it would start on the second or third attempt. The battery showed as fully charged and we had the starter motor bench tested and checked all wiring possible. In the end it was decided the ignition barrel was faulty so it was changed and this seemed to cure the problem until however we launched last week and it is exactly the same as last year – an intermittent fault that could prove very inconvenient. My thought is possibly the starter solenoid (not sure if this was tested along with the starter motor last year), in which case a relatively easy fix. Before I go down this route are there any thoughts from the panel please?

 

[LadyInBed]

When turning the key, if the solenoid was operating but the starter motor not turning, you should be able to hear the clunk from the solenoid.
If you can, that suggests a solenoid contact problem.
If no clunk, that suggests to me a wiring/connection problem. If you can put an ammeter in the circuit or an amp clamp, this will tell you if it's a broken or poor (high resistance) connection.

 

[Spyro]

High resistance between ignition switch and starter solenoid. This was a very common problem on GM series. A jumper cable from battery positive to the starter solenoid would prove the problem and get you started. Google yammer gm starting problem

 

[Spirit (of Glenans)]

At the start of last season we had an issue with our previously very reliable Yanmar 3YM20 – when turning the ignition key the warning alarm sounded but absolutely nothing happened – completely dead; generally it would start on the second or third attempt. The battery showed as fully charged and we had the starter motor bench tested and checked all wiring possible. In the end it was decided the ignition barrel was faulty so it was changed and this seemed to cure the problem until however we launched last week and it is exactly the same as last year – an intermittent fault that could prove very inconvenient. My thought is possibly the starter solenoid (not sure if this was tested along with the starter motor last year), in which case a relatively easy fix. Before I go down this route are there any thoughts from the panel please?

Not just inconvenient, but potentially dangerous.

 

[John 32i]

Thanks both - much appreciated.

 

[Tranona]

I don't know if the YM is the same as the GM, but on the latter unreliable starting is often due to bad contacts in the loom, either the connectors or particularly the fuse in a holder in the wiring.

 

[VicS]

At the start of last season we had an issue with our previously very reliable Yanmar 3YM20 – when turning the ignition key the warning alarm sounded but absolutely nothing happened – completely dead; generally it would start on the second or third attempt. The battery showed as fully charged and we had the starter motor bench tested and checked all wiring possible. In the end it was decided the ignition barrel was faulty so it was changed and this seemed to cure the problem until however we launched last week and it is exactly the same as last year – an intermittent fault that could prove very inconvenient. My thought is possibly the starter solenoid (not sure if this was tested along with the starter motor last year), in which case a relatively easy fix. Before I go down this route are there any thoughts from the panel please?

There is also a relay in the circuit between the control panel and the starter motor solenoid. Every one seems to be ignoring this.

You will need to check systematically to determine if the fault is:-

• in the panel ( eg a faulty key switch)
• In the wiring between the panel and the relay
• a faulty relay ( which can be replaced with a heavy duty automotive relay if necessary)
• A connection between the relay and the solenoid ( not the most likely)
• the solenoid

Refer to the wing diagram in your owners manual and the snip below which just shows the relay , solenoid and starter.

 

[alahol2]

I had very similar symptoms last year. It eventually turned out to be a faulty battery master switch, It would pass a small current, enough to get a reading on a multimeter, but not enough to turn the starter.