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Power problem

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Vaboat

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Searay 2004 5.0 mercruiser new engine placed 2 years ago because old engine broke rod. New engine working well but now with power problems. Unable to exceed 3000 rpm with load. Neutral able to get 4800rpm. No change in prop. Fuel systems and exhaust systems checked and normal. Can it be an electrical issue at the main connector Also the tach gauge occ is erratic. It idles perfect all day long.also new lower unit placed at time of new engine. Help please the mechanic has had it for 8 weeks. Replaced new ignition module ,new plugs, checked gas,,exhaust flappers ok
 
Providing the serial number will help give us insight into the configuration of the engine.

Any idea what checks were done on the fuel system?
 
Like Mark said above, still need serial number.

A jumpy tach frequently indicates a misfire. Did he replace cap/rotor & wires? Did he check compression?

Gut feeling especially if a carburated engine is you have misfire and considering the amount of power loss you may only be hitting on 6 cylinders.

Did issue develop instantly or gradually? Could 2 plug wires have gotten reversed during routine maintenance?
 
Compression 165 all cylinders, New Delco ignition placed so new cap and wires has checked fuel pump and filter checked
 
Alpha drive or Bravo drive?
If Alpha, check shift interuptor switch. They fail & timing will go all over the place. May check OK statically but be intermittent with engine vibration.
 
Vaboat said:
Compression 165 all cylinders, New Delco ignition placed so new cap and wires has checked fuel pump and filter checked
Click to expand...
so they put a Delco Est on in place of the merc thunderbolt? First thought is maybe distributor moved and timing is not right or it is not advancing should be 10-12 deg BTDC at idle (Delco will move around if not put in base mode, total advance should be 25-28 or so at 28000 rpm.
 
Back to post #6, if the shift interuptor is faulty & vibration is causing contacts to open & close off schedule timing will vary all over the place.

Also, if the shift cable is a bit out of adjustment (as in too much fwd adjusted into cable/system) when selected into fwd gear the fork could be beginning to travel & depress the interuptor switch when it should be sitting centered in the "V" notch.
 
I think it would be helpful to know what we are dealing with - carb or EFI...and any other changes made (like the delco ignition swap)...
 
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