Mercruiser 3.0 DDIS loses power after planning

[Trs560]

We have a 99 sea ray with 3.0 mercruiser ddis purchased a year an a half ago. Ran fine originally but noticed the fuel pump leaking last season and replaced it. After riding the lake for several hours the motor began to intermittently cut out like trying to run out of gas then acted sluggish, giving it full drive power and going at a snails crawl, it would eventually die. We'd let it set and it would recover for a small amount of time then once again. Even though the ignition ommed out good we replaced it with another.. On the trailer with muffs sounded great, took to the lake and after 10 minutes same old story but this time it wouldn't start after dying, we managed to flood it and had to be pulled in. Sparkplug looks good filters not bad but replaced anyways. Any ideas?

 

[Maclin]

Welcome Aboard!

Check the fuel tank venting by loosening the fuel fill cap when this happens. If a tank does not vent well for whatever reason then what you are describing is one of the symptoms.

Another thing to check would be the anti-siphon valve, that is what the main fuel line from the tank connects to.

 

[211libwtfo]

+10,000 on the anti siphon valve.

 

[Trs560]

Thanks I'll check that tonight.

 

[Trs560]

I checked but that didn't seem to be the issue, not sure it is a delivery problem because when it starts spitting and slowing down I'll give it gas and the motor will reave like plenty of power but just not moving forward..then eventually spits until it dies. Any thoughts.

 

[Bondo]

not sure it is a delivery problem because when it starts spitting and slowing down I'll give it gas and the motor will reave like plenty of power but just not moving forward..

Ayuh,..... Welcome Aboard,.... Please explain this quote,.....

 

[Trs560]

Sure.. Planned out everything fine.. Starts out as just a sputter.. Yes like running out of gas and the forward power gone like pulling back on the throttle..i try giving it more pushing the throttle forward and the motor rpm increases but the boat just stops moving then eventually dies.

 

[Bondo]

Sure.. Planned out everything fine.. Starts out as just a sputter.. Yes like running out of gas and the forward power gone like pulling back on the throttle..i try giving it more pushing the throttle forward and the motor rpm increases but the boat just stops moving then eventually dies.

Ayuh,.... It sounds like the fuel delivery issue, combined with a slippin' prop hub,.....

For the fuel, try runnin' it on a remote tank of fresh clean gasoline, hooked right to the fuel pump,.....

For the prop slip, put on another prop,....

 

[achris]

That sounds like a coupler or prop hub going bad, but doesn't explain the stalling. How's the engine temperature? (If is a coupler, then the water pump isn't pumping and the engine could be sitting down due to overheat).

 

[Trs560]

Gets on the warm side but not hot.. Just above normal.