Throttle? Fuel? Something Else?

[tvogz]

Hi all,

I have been attempting to fix an issue all season. 2000 3.0 GS/ SX M. It may not even be an issue, but it is somewhat irritating. Engine seems to run great. Full tune up this spring. If I take the throttle lever to somewhere between 75-85% I can somewhat hit my WOT RPM with trimming and enough time. If I push the throttle to full 100%/90degrees/9:00 the engine drops RPM to around 4000 and I lose power and speed. Any ideas?
Thanks

 

[GA_Boater]

Check for spark on all 4 cylinders and compression. You may have a dead cylinder.

 

[tvogz]

I'll take a look at that in the morning. I wasn't thinking this since I am able to get into the 4400-4500 range for RPM with good acceleration up to it, It just happens at 75-80% throttle rather then full.

 

[tvogz]

Timing checks right on. I have been chasing this like it's a fuel supply issue, and just replaced the throttle control cable today, but after a test run, it's still there. New distributor, rotor, wires and plugs this spring. Replaced fuel filter and filter at Carb inlet. I don't think it's the carb. I have a spare and the issue was there with both carbs.

 

[tvogz]

Started looking at the throttle cable this morning. Unhooked from the carb it will pull a good additional inch beyond where the throttle plate wants to stop. Full open throttle on the carb actually hits at about the 3/4 travel. Can this be adjusted out?