84 carver 26 with 350 merc thunderbolt iv will not get over 3200 rpm

[brixhomeservices]

Hey there, I'm having an issue with my boat. I had my engine rebuilt 2 seasons ago and have had no issues at all until now. I have always ran about 5200 rpm but now she will not get past 3200 rpm. She will rev in neutral up to 5400 or so but not under load. If I hammer down on the throttle she backfires and then goes or it dies. If I ease into it she gets up no problem but won't go past the 3200 rpm. I have changed fuel filters and water separator, checked the filter basket in the carb. Changed plugs, wires, and coil. Cleaned cap and rotor. I'm thinking accelerator pump or ignition module. Also the choke is not sticking. Anyone wanna put in their two cents?

 

[NHGuy]

Does it run smoothly? Did you check the timing? Recheck that your wires are on the right plugs and that they are tight. Get some wire separators and rig the wires so they don't touch one another. Does the timing advance to around 30 btdc by the time it revs way up? I think "all in " is in around 2500 or so rpm.
Are you dragging any junk along the bottom of your boat? Any stuff living on your hull? Is your prop good?
At that rpm with a heavy boat like a Carver you should be hearing the howl of the carburetor secondaries opening. Does it sound like it used to?
The accelerator pump can be an issue but it's really just for takeoffs. The backfiring and dying can be wires, timing, fuel clog.
Can you ease it up to 3000 and then hammer it? Does it go, or bog, or pop?
Check the sticky too....http://forums.iboats.com/showthread.php?t=295070

 

[brixhomeservices]

I will check the timing today, I don't understand how it would have changed though. On Saturday the boat ran great, then Sunday it started this nonsense. I didn't even open the engine compartment Saturday. Doesn't the ignition module control the timing advance?