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Volvo Penta kad 300 reduced power

curtis

New member
Hello,

I have a 2003 Volvo Penta in an Albemarle 26 with only 170 hours. I have only owned the boat 1 month. The original owner used it infrequently and it is like new condition.

Recently while cruising offshore at about 3700 rpms, the engine immediately rolled back to around 3000 rpms. We stopped the boat and investigated in the engine compartment and found no obvious trouble. We proceeded once again and about 20-30 seconds after planing at 3700 rpm, the engine again reduced power without throttle movement to 2900-3000 rpms. We then limped home. No fault codes from the EDC were generated and no alarms (oil, temp, etc). Strangely, I have noticed that on numerous trial runs since then, full power is available each time until the temperature gauge reaches around 190 degrees and then the engine automatically reduces power to 3000 rpms.

I checked the raw water side for obstructions but everything was clear. There was no debris in the sea strainer and the water pump and impeller were functioning normal. I then took the boat to a local VP service shop and they are also checked the raw water system and ruled out problems there. They checked with tech services and were instructed to see if there was condensation at the boost pump sensor and if not, remove the fuel injection pump and injectors for inspection and cleaning which they are doing now. They suspect that diesel sitting in the engine may have gummed up the injection system somewhere. However, it seems like the engine is sensing a operating limit and is thereby limiting power to protect itself. There is 1 temperature sensor to the EDC and 1 temp sensor to the gauge so I am wondering if the EDC sensor or possibly another sensor may be faulty.

Has anyone had a similar issue recommendations how to proceed?
 
I don't know that particular engine, but 3000rpm doesn't sound like a roll-back protection rpm number and I would be more suspect of the fuel delivery and boost. I would have run a boost gauge over the engine before pulling the fuel system. Could be a small split in a air line etc leaking boost under pressure at high boost numbers. Some sort of exhaust blockage could cause similar, but seems less likely. also check for air leaks around your fuel filters, and of course the filters themselves should be changed in case they are restricting fuel flow. Filters, boost, then fuel system if I was doing it.
 
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