strange guardian mode issue

[bman440440]

we just splashed my buddy's boat yesterday and he is having a strange issue... when rolling into the throttles no issues until after 4100 RPM's +/- then both (starboard first then port separated by about 1-2 seconds) engines go into guardian mode (no lights or warnings on the gauges) or if you get into the throttles hard and fast it happens much much faster and much lower RPM's and again no lights or warning on the gauges... just the buzzers going off and reduced power ( I think they will go down to 2000 RPM's)... the engines are 2005's with the exhaust updates done and a fresh service (oil, plugs, water pumps etc.) and water is coming out of the tattle tale's nice and hard like normal... and as far as fuel there was about 80 gallons in it with marine stabil that is about 6 months old and before we splashed it we put another 108 gallons of fresh fuel... I'm an I/O guy so I'm looking for this forums vast knowledge base on these engines so any help would be great!!

 

[rejesterd]

Are these Yamahas? What model?

 

[bman440440]

Are these Yamahas? What model?

yami's... 2005 f225's

 

[GA_Boater]

With both motors going into guardian, what's common? Is fuel supplied from a single tank?

 

[bman440440]

With both motors going into guardian, what's common? Is fuel supplied from a single tank?

single tank dual pickup's... and I did check to see if the primer bulbs where collapsing and they where not.

 

[rejesterd]

First of all, I would say the problem is in the starboard engine. If one of the engines enters any one of the control modes (i.e. reducing the rpms or completely shutting down ignition), that engine will now control the other's ignition.

One of the control modes is activated when the engine is running over 4500 rpm and thinks it's in neutral. But that should completely kill the engine, which doesn't happen in your case.

Another control mode is when you're going forward or reverse over 6200 rpm. That's the redline limiter, and it will start shutting down cylinders depending how far you go over 6200. That sounds more like your issue, but you're not anywhere near 6200.

But regardless, the ECM controls all the modes. You can try swapping the ECMs between starboard and port, and see if port starts shutting down first. If so, I would say that ECM is bad. However, that means you have to run the engine to do this test. If there's a serious issue with the engine mechanically (which is possible), you don't want to keep running it.

Another option that's probably better would be to get the YDS cable & software, and see if either ECM is throwing any error codes. You don't have to run the engine to do that. Also, get the service manual and measure the output peak voltage of the ECM and pulser coil to see if they're within spec.

 

[GA_Boater]

You might pull a fuel sample through the pickups. Got water separators/filters in the system?

 

[rejesterd]

And check the thermostat. The fact that it's peeing well indicates the water pump is fine, but that doesn't say anything about water getting into the cooling passages downstream of the thermostat. I'd be surprised if your overheat warning light was broken, but it's possible.

 

[bman440440]

You might pull a fuel sample through the pickups. Got water separators/filters in the system?

yes dual fuel/water separator filters

 

[bman440440]

And check the thermostat. The fact that it's peeing well indicates the water pump is fine, but that doesn't say anything about water getting into the cooling passages downstream of the thermostat. I'd be surprised if your overheat warning light was broken, but it's possible.

possible I agree... but on both engine displays??... and only having issues when rolling in the the throttles quickly?

 

[rejesterd]

possible I agree... but on both engine displays??... and only having issues when rolling in the the throttles quickly?

I don't think both overheat lights would come on if only one of the engines is overheating, because those are triggered by each engine's temp sensor. But I do know that when one engine goes into a controlled mode, it causes the other one to go into the same mode.

Also, you can take a heat gun and point it at the engine block to confirm if it's actually overheating. But again, it's not an active test you really want to perform unless you feel like replacing a head gasket afterwards

But if the buzzer goes off immediately when the throttle is opened quickly, and when the engine is cold or just slightly warm, it's not actually overheating.

 

[GA_Boater]

What happens when the motors are run independently? One is not started and try to reach WOT with the other. Since the port motor lags starboard, try port only, then starboard.

Are these fly by wire digital or mechanical control motors?

 

[bman440440]

What happens when the motors are run independently? One is not started and try to reach WOT with the other. Since the port motor lags starboard, try port only, then starboard.

Are these fly by wire digital or mechanical control motors?

I will have him give that a try and report back. they are mechanical control motors... did they have fly by wire in 2005?

 

[GA_Boater]

I'm not sure, but I believe fly by wire could be retrofitted.

The reason I asked is FBW could have motor synchronization and if the master was the starboard motor it would throttle down the port motor to match RPMs.

 

[bman440440]

I'm not sure, but I believe fly by wire could be retrofitted.

The reason I asked is FBW could have motor synchronization and if the master was the starboard motor it would throttle down the port motor to match RPMs.

ahhhhhh

 

[GA_Boater]

The couple seconds of delay before the port side slows could be the sync kicking in. There are synchronizers for manual motors, too. Something to look into.

BTW - Is this a new boat for your Bud?

 

[bman440440]

The couple seconds of delay before the port side slows could be the sync kicking in. There are synchronizers for manual motors, too. Something to look into.

BTW - Is this a new boat for your Bud?

I don't think that there are sync's on it... I know when we motor out we have to tap the throttles to match rpm's... and no not new to him boat... he has had it about 12 years now

 

[bman440440]

we are going down there tomorrow to do some testing... I will update with what happened tomorrow in the P.M.

 

[bman440440]

well the mystery has been solved... it was a trim level sensor... it had a cracked wire and was intermittent... did a temporary repair and issue solved... new one being shipped now... figure go ahead and replace them both and be done with it!

 

[GA_Boater]

OK, Bman - How in the heck did you find that one?

Trim level sensor! I'm sure one of the replies mentioned that.