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I've got a 1999 Ski Nautique with the PCM GT-40 motor. Recently I've been having several issues that are preventing me from getting on the water.
For the past season or two, I've been having trouble with restarting the motor after running for a while. It'll fire right up, but it'll lope and surge. Typically the RPM will drop from 600 to 400 and then surge to 800-1000 and then drop again. It's been getting worse and worse, on Saturday it was ranging from nearly stalling to 1000 rpm. We had been cruising for an hour and then we'd been sitting for an hour. I have no idea what is causing this, within the past 5 years the boat has had both fuel pumps replaced and a new ECU installed. Perhaps it is related to my other more pressing issue.
Last time I was on the water, my check engine light was intermittently coming on and off. It would come on during low speed and shut off once I was on plane. My water temp gauge was reading normal, about 175-180 at idle and 160 at cruise. However, when I restarted the boat after stopping for a swim, I had a problem with the circulating pump. It wouldn't turn when the engine started, the belts were tight but still slipped. I stopped it and tried again. This time, it spun without problem. I idled out of the bay and when I tried to take off the engine cut out, exactly like an engine that has overheated. However, my temp gauge was still reading at a steady 175.
I limped her home and popped the hood. The port manifold is absolutely scorching while the starboard manifold is hot, but safe to touch. I let it cool and checked the thermostat (fine), raw water pump (fine), and the circulating pump (also totally fine). When I start it up at the dock, the port manifold is uncomfortably hot with 1 minute of running and the starboard manifold is fine. I disconnected the port side water hose running into the manifold, it has great flow.
Is my manifold blocked, causing the overheating? How can I test this or fix this? I have no dealerships in my area willing to work on inboards.
For the past season or two, I've been having trouble with restarting the motor after running for a while. It'll fire right up, but it'll lope and surge. Typically the RPM will drop from 600 to 400 and then surge to 800-1000 and then drop again. It's been getting worse and worse, on Saturday it was ranging from nearly stalling to 1000 rpm. We had been cruising for an hour and then we'd been sitting for an hour. I have no idea what is causing this, within the past 5 years the boat has had both fuel pumps replaced and a new ECU installed. Perhaps it is related to my other more pressing issue.
Last time I was on the water, my check engine light was intermittently coming on and off. It would come on during low speed and shut off once I was on plane. My water temp gauge was reading normal, about 175-180 at idle and 160 at cruise. However, when I restarted the boat after stopping for a swim, I had a problem with the circulating pump. It wouldn't turn when the engine started, the belts were tight but still slipped. I stopped it and tried again. This time, it spun without problem. I idled out of the bay and when I tried to take off the engine cut out, exactly like an engine that has overheated. However, my temp gauge was still reading at a steady 175.
I limped her home and popped the hood. The port manifold is absolutely scorching while the starboard manifold is hot, but safe to touch. I let it cool and checked the thermostat (fine), raw water pump (fine), and the circulating pump (also totally fine). When I start it up at the dock, the port manifold is uncomfortably hot with 1 minute of running and the starboard manifold is fine. I disconnected the port side water hose running into the manifold, it has great flow.
Is my manifold blocked, causing the overheating? How can I test this or fix this? I have no dealerships in my area willing to work on inboards.