1996 Mercruiser 4.3 will not get over 2600 RPM under load.

Hello, has anyone had an issues with motor starting fine, revs fine at the dock, when get it out on the water, will not get above 2600 RPM. I can put it wide open and doesn't go any higher. I tried working up slowly, hammering it down, and pumping it, still nothing. My first guess could be bad gas or filter, but boat is an hour drive away so wanted to be prepared if that does not fix it. Thank you.

Re: 1996 Mercruiser 4.3 will not get over 2600 RPM under load.

Here is a 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.

Re: 1996 Mercruiser 4.3 will not get over 2600 RPM under load.

Thank you for the check list. Some of them I can eliminate from the start. Nothing has been changed out of the engine since they winterized it last year and was just put in the water 1 week ago, so any of those issues should be out. I have twins, and the other one performed well with same octane gas. They are one 2 different tanks, so there is a possibility that water got in this one. Is there any carb treatment or octain booster you would rcommend? I typically treat my gas with seafoam.