MerCruiser Warm Stop Condition

Troubleshooting the MerCruiser Warm Stop Condition

So we are now to the point of either sorting out minor issues or dealing with a larger one. Up to this point, there have been a few challenges. The latest is the MerCruiser Warm Stop Condition. We changed the oil and oil filter after we ran into the issue last week. I’ve replaced the oil pressure switch and sender. The SmartCraft Four in one Gauge oil pressure works fine now and does not bounce around! So maybe this issue with the engine stopping when warm is related to the engine Guardian.

MerCruiser Warm Stop Condition Round Two

So I pull the boat out and hook her back up to the water ears. Additionally, I turn on the water and do a quick inspection that things are good to run her on the water ears. I start her up and within three or four minutes she sputters and dies! So the idea this is related to the oil pressure and the engine Guardian strategy is not the case.

Pull out the Rinda Diagnostic tool (Round Two)

So I grab the Rinda tester and read the fault codes. So last week we had these codes from here. There are none, nice! So let’s log some data here and see what we see? Now googling around it seems that this could be related to the Idle Air Controller Valve (IAC). What I notice is that at startup there is a sound of air and as it dies, this sound seems to diminish or go away entirely. It actually only got to ninety-five degrees and stalled. I put the fuel pressure tester on the Shrader valve and start the engine looking at the data being logged. What I see from the IAC right before it stalls is that it goes to IAC duration drops from forty percent to zero and stalls. When it is restarted, it stumbles as it opens for forty percent then slowly drops to zero and stalls.

Suspect The Idle Air Controller Valve!

IAC Connector
IAC Connector

So there is a pink and Black wire on this connector, that goes back to the ECM. The connector looks like it has seen better days. So I start her back up and wiggle the connector while it’s running. It does not stall while doing this, but a minute later it stalls. I also hear a muffled backfire through the intake. It’s exhibiting all the behavior of last week! I disconnect the IAC and try and start it. Additionally, it plain won’t start like this. So I’m now thinking this is it. So off to the internet to order an IAC. It’s Saturday, with very little chance of getting before next week.

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