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Mercruiser 5.0l acceleration problem

D

dav

New member
Hi guys, I've got a '98 Regal with dual Mercruiser 5.0l EFI engines. The port engine has developed an acceleration problem. When I advance the throttles both engines accelerate to approx. 2600 rpm at which time the port engine begins to lag no matter how far I advance the throttle. When I get on plane the port engine decides to play and comes up to its' normal rpm, slowly. Once on plane I get equal WOT of about 3900 rpms from both engines.

I've replaced the fuel/water separator, the anti-siphon valve, all spark plugs,wires,distributor and rotor.

Any suggestions?
 
Once on plane I get equal WOT of about 3900 rpms from both engines.
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Ayuh,... Yer Way over-propped, 'n luggin' yer motors,...

When were they last given a Tune Up,..??
 
bondo said:
Ayuh,... Yer Way over-propped, 'n luggin' yer motors,...

When were they last given a Tune Up,..??
Click to expand...
Agreeing with bondo, Sounds like it may be too big of an propeller.

Hopefully you haven't damaged the engine internally.

Is the boat an I/O or inboard?
 
Your engines need to run WOT between 4400-4800 RPM. If the engines are running per design then the boat is overpropped as stated or it has gained quite a bit of weight. Assuming you load it properly underway then check the floor, stringers and transom for water logging. Use a moisture meter to test if it is not obvious. If you find moisture then you can bet the floatation foam is water logged. The only way to fix it is to start over from the hull up and replace all the foam, stringers, floor and transom. BTDT!

The following link is one of the best rebuild series I have ever seen. http://www.youtube.com/watch?v=uD1rK8Ail2I&list=PL02C318B574CD948D
 
I agree... may i add perform a compression test. Keep track of what plug comes out of what hole...write down the numbers and cylinders.

Post back.
 
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