Strange Phenomenon -- 4.3L losing rpm??

[canadianguide]

Had my boat out wednesday...4000rpm at WOT (*see "Yet another prop question topic") Anyway, took it out again this weekend, and WOT is now 3000rpm. I'm still hitting the same top speed (up to 45mph) but I believe I should be running at around 4400rpm WOT with this engine. <br /><br />The boat is a 1986 Baja Islander 180 with a Cobra Sterndrive. The engine is a 91, freshly rebuilt and installed (IE brand new). <br /><br />Why would this be happening if nothing has changed? Especially if the top speed really hasn't changed?

 

[Skipster1]

Re: Strange Phenomenon -- 4.3L losing rpm??

Sounds like your Tachometer is going bad.<br />Does the engine actually sound slower at 45mph than it used to??????

 

[canadianguide]

Re: Strange Phenomenon -- 4.3L losing rpm??

not really no...didnt realize a tach could go bad??

 

[Tufan]

Re: Strange Phenomenon -- 4.3L losing rpm??

I'd also check the tach connection wires, considering it is 86... maybe rusted -