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power problems under load

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bshrove

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I have a 1987 140hp merc (GM) that runs great with no load, when i get it out in the water it will troll fine around 1000 RPMs but when i give it wide open throttle most of the time it will get to around 3000-3200 rpms and start fluttering bad, but once in a great while it will go to full throttle around 4200 rpms and get up on plane and run great. it has been sitting for the last 4 years but ran great when i parked it and had the prop rebuilt. i was thinking it may be a carb problem but not positive so thought i would ask the experts. thanks for any help you can give (btw still running points for now untill i can find a replacement hei dist any one have one?)
 
I would say your carb definetely needs rebuilt, and your whole fuel system needs cleaned out. A motor that sits for 4 years needs some good TLC. Just because it ran great 4 years doesn't mean it's gonna run great anymore.
 
yea i figured that but thought there might be an underlying problem that i could check before going out next time, to get it on the water is an hour away
 
Re: Lack of power no rpm over 3000rpm

List of possible causes of low WOT

List of possible causes of low WOT (Wide Open Throttle) rpm.

In no particular order

Engine Won't Reach Operating RPM. Check

1. Fuel condition. Type and Octane possibly old fuel
2. Propeller pitch or diameter, damaged blades
3. Restricted fuel pickup tube or anti siphon valve Fuel System Test
4. Crankcase oil volume, high oil level can cause aerated oil and lifter collapse
5. Marine growth on hull and outdrive
6. Wrong gear ratio in outdrive
7. Restricted carburetor air intake (clogged flame arrestor)
8. Restricted exhaust system (broken exhaust shutters/flappers) in engine transom shield or drive
9. Poor cylinder compression Compression Test
10. Carburetor defective, or wrong type.
11. Fuel pump pressure and vacuum
12. Boat overloaded, improperly loaded, or improperly trimmed.
13. Engine Overheating
14. Engine timing and ignition system operation
15. Remote control cables and linkage for proper travel to open throttle plates fully.

Above copied nd pasted from another website Don s is the author.

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