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2006 mercruiser 43litre mpi stalling

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idomeneus5

New member
"Hi guys, hope some one out th

"Hi guys, hope some one out there can help. I re engined my 23ft aft berth cruiser (similar to sea ray) with a brand new 4.3litre mpi mercruiser. It has been running ok ( apart from a burnt out fuel pump). But I seem to have a stalling problem at low speeds when weight distribution is toward the stern or when "driving off" the trailer on a steep ramp.. The boat is licensed to carry 8, the main seating area is at the stern. This causes the thru prop exhaust to sit lower in the water, and the engine stalls, taking some time 5-10mins to restart unless I use the throttle. I guess I could liken it to sticking something up a car exhaust pipe. Raising the prop does not help, but moving weight forward alleviates problem. I can live with the problem while "wet berthed" but when launching from the trailer if the engine stalls then it meanS I have to man handle 2.6 tonnes of boat off the trailer. I have read somewhere on the web, within the last 18 months of drilling holes throught the leg to allow the exhaust gasses to exit higher up, the article (which I now cant find) even mentioned there being "dimples" on the leg to facilitate the positioning of the holes. My mechanic is sceptical of the idea, but then he's the one who burnt out the fuel pump. Merc Australia replaced it under warranty. any advice greatly appreciated, thanks Peter P."
 
"why was the engine replaced a

"why was the engine replaced and when it was replaced did you check out the water shutters / flappers to make sure they where intact?? if not you might check them out as they might be restricting your exhaust. also if changing the weight in the boat changes or makes the problem have you thought it might be the fuel in the tank as to the fuel pick-up (how much fuel is in the tank) , I have never heard of the exhaust being too far under water to make the motor stall. but I have heard of the shutters restricting or letting water come back up the exhaust and stalling the motor.."
 
"Peter,
I think you may have

"Peter,
I think you may have a potentially very serious water intrusion issue. Have you checked the riser height (above the waterline)? I suspect that your going to have to add a riser kit."
 
Don't let anyone in the bo

Don't let anyone in the boat until it's running; a good safety practice in case there is a fire or explosion.
 
"Bill K. Previous engine was a

"Bill K. Previous engine was an omc cobra, which was well past its use by date. The previous owner had damaged it internally and to get the replacement parts, if available (they weren't in Australia) and to get them shipped to me were exhorbitant. Plus the engine was 15 years old, and had just had a fair bit of money spent on it prior to my purchase. "what else could go wrong".
The original plan had been to replace it for a more economical engine when I retired.So got a good deal on brand new engine & leg.

Dave n. will speak to mechanic when I pick it up in a couple of hours, she's in for a 50 hour service, prior to the november long weekend. Will keep you posted. Thanks guys Peter"
 
"Bill/Dave. Picked her up and

"Bill/Dave. Picked her up and mentioned your thoughts to my mechanic. Riser height would appear to be ok. and "shutters" are ok. What has been suggested is to remove the "standard exhaust bellows" and to replace it with an open ended bellows arrangement. This being a sturdy rubber tupe that is fixed to the transom assembly, where the standard bellows would be fixed, using the clip from the existing bellows. the other end is open and closes over the leg flange when the engine is trimmed midway to fully down. This allows exhaust gasses to escape higher up albeit the engine is a trifle more noisy at idle, but will add 1-2 more h/power. At speed the noise is unnoticable. The part is supplied by mercury and apparantly is standard on all V8's. I presume (i.e. forgot to ask) that the is some sort of one way "valve" at the fixed end to stop water entering. He even showed me an engine with it fitted, so as to enable me to fit it myself. This system would appear to make sense. Your thought please. Peter."
 
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