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Loss of Power

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sinkerstinker

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Hi I have a MCM-140 engine. T

Hi I have a MCM-140 engine. The boat was running good for 1/2 day then lost most of it's power. When giving it throttle the engine sounds like it is flooding or bogging down. The boat tries to come up and plane but has no go. The more I give it the worse it sounds. Was running gas out of an extra tank boat tanks are dirty and not running 88 or high like they said I should have been. If anyone could give me some help I would greatly appreciate it.
 
you want to change fuel filter

you want to change fuel filters and check to see if any fuel present in clear line to carb that would indicate fuel pump failure. Make sure the choke is opening fully. 87 octane fine
 
Thank you for the response. I

Thank you for the response. I was moving the boat around with not much throttle to dock. Can I still be running the engine with a fuel pump failure? Could you tell me how to check to see if the choke is opening fully. Thank you
 
"Carlene

With the engine at

"Carlene

With the engine at operating temp the choke plate should be nearly vertical. W/a cold engine the choke should be closed horizontally all but 1/8". The picture below shows a typical 2 barrel carb w/the choke plate closed.

http://www.mercruiserparts.com/showSpecialPicture.asp?pn=807504A1

In this blowup diagram item 1 shows the choke plate in the vertical position.

http://www.mercruiserparts.com/Show_Pictures3.asp?dnbr=816323%2090&ivar=images/C RUISER/816323.90/29.png&inbr=1604&bnbr=130&bdesc=CARBURETOR+%28MERCARB%29+0D4474 15+THRU+0D836075"
 
Thank you Guy.
Do you think p

Thank you Guy.
Do you think power loss is from carb or fuel pump? Or both? Trying to learn a much as I can about my engine. Thanks!!!!!
 
Hystat gave you good advice.

Hystat gave you good advice. Fuel in the transparent plastic line means the pump is shot. It would flood the engine. If the carb has not been gone over in a number of years it might be the culprit espec. since you said the tanks were dirty.
 
Thank you Hystat and Guy. The

Thank you Hystat and Guy. The plastic line has no fuel in it and I was running gas out of a gas jug (gas tanks not hooked up). The boat is an 82 and has not been run for a number of years so I think a carb kit is probably in order. Thank you so much for all the help.
 
Let us all know the outcome an

Let us all know the outcome and what it took to get it running. Ask all the questions you want; the only stupid question is the one not asked.
 
Ok Boy's Here it goes! Car

Ok Boy's Here it goes! Carb had alittle junk and fuel pump is fine. Valves had low compression-getting a valve job. Head was warped not cracked from bolts not being torched right or heat?? Please tell me what causes head problems and how to avoid them and do valves just wear over time.
Thanks!!
 
Warped head: most likely the e

Warped head: most likely the engine overheated at some time in the past... A list of things could cause this including improper winterization (if you live where it freezes) to worn raw water impellers...etc.
 
Exhaust valves can burn after

Exhaust valves can burn after a long time but should last the life of the engine. Intake valves will easily foul w/carbon and crud from cheap gas; stick w/name brand fuels. Time will take its toll on the heads w/neglect of the engine cooling system.

Did the tech. run a "wet" (tbsp. of oil in cylinders) compression test to check the rings for wear?
 
Not sure about the wet test? P

Not sure about the wet test? Please tell me how to maintain the engine so this does not happen again. Engine cooling system? What octane is best? Thanks
 
"Head was warped not crack

"Head was warped not cracked...getting a valve job"

Is the mech. having the head milled to true it? I would replace a head that is warped and that old.
 
""how to maintain the engi

""how to maintain the engine so this does not happen again"

Regular scheduled oil/filter maint., quality fuel w/stabilizer if not being used up in 3-4 weeks, keeping the engine tuned. Run it on 87 octane; if it knocks jump to 89, then 91."
 
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