5.0 sx no power.

[hankj]

I have a 24ft 94 baha chruiser with 5.0 sx drive.I replaced the engine in 2007 and it ran great.Now it has no power above 3000 rpms .I change all the ignition parts ( coil,rotor, pick up,mod cap, plugs) and also rebuilt the carb twice with no results.It starts and idles fine ,will rev in neutral with no problem it sounds good, but under a load it won't rev past 3000 rpms.The boat barely planes but should run 30mph.I also checked the carb opens all the way.I have cleaned the boats bottom and changed the prop with no results.I don't no what I could have missed.Any ideas?
Thanks

 

[duo_prop_dad]

Firing order correct?

Did you set/ check ignition timing after the tune-up?.

Does your distributor have mechanical advance? It may be corroded and inoperable....

John

 

[hankj]

Thanks John
yes the firing order is correct and the timing has been reset.The distributor dose not have mechanical advance ,its done with the module.What your asking makes sence it runs like it needs more ignition timing.

 

[hystat]

change fuel filter, check anti-siphon valve at the fuel tank, clean flame arrester