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What causes Engine limit to 3000 RPM

J

johnathsv

New member
1995 Mercury(model:1115412

1995 Mercury(model:1115412RT) 4CYL-115HP
(sn#0G243098) with 11P prop on 30 foot pontoon has hesitation on acceleration and with wide open throttle runs at 3000 RPM - Carbs have recently been cleaned( motor seems to start and run normal) - Voltage & Stator were replaced new two years ago - not sure when the engine transitioned from 4700-5000 rpm to current 3000rpm maxium. Any Suggestions?- Thanks in advance. jh
 
"Yes, then confirm spark at al

"Yes, then confirm spark at all 4 cylinders (timing light will give you an answer in a minute or two).

How old is the gas? sparkplugs? - two weeks old is OLD GAS - last years sparkplugs are OLD.

Could also be carbon/cooties in the powerhead - a $5 can of Merc's "PowerTune" (available in a spray can from many marine dealers) can do wonders and is particularly useful when a motor first comes out of storage - just follow the directions on the can.."
 
"Thanks, I have checked comprs

"Thanks, I have checked comprssion( all 4cyls at 132psi) - Cleaned all four carbs - changed to new gas- Still have only 3000rpm at WOT."
 
Marine Growth on hull??? Is

Marine Growth on hull??? Is this the yamaha based 2+2 engine??? That engine can be identified by the absence of Idle mixture screws on the bottom two carburetors.
 
"Thanks, Pontoon floats have b

"Thanks, Pontoon floats have been cleaned/ no growth on hull- Yes, it is a 4 cycl - Idles on mostly two cycls, but then kicks into all four with increased throttle...."
 
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