I have an 85 GSL-SE that I have owned for 10 years (my 6th 1st Gen going back 30 years). It has 163K on it and had been running fine. It is garaged and maintained regularly. recently i noticed it has begun to bog down when trying to rev it higher than 4K RPM's and am at a loss as to what it could be. It has been tuned recently and does not miss or seem to have a fuel restriction when kept under 4K RPM's and runs just fine when I don't race it a little-which defeats the purpose of owning it. It is pretty much stock other than a mind train cat-back exhaust put on it some time ago. I also should add that I plan to take out the catalytic converter and put in headers. I have been told this problem may be an exhaust restriction as well and I don't know enough about it to speculate if the catalytic converter may be causing the issue but I will be taking it out anyway. Any suggestions are appreciated.

-Ted

 

Could be your 5th and 6th ports are not opening up. They are supposed to open up at 3800 rpm I believe. This would affect your upper end performance. A loss of 20+ HP above 3800 rpm. But this problem is so subtle most people don't even know they have the problem. If you're feeling a almost complete loss of power at 4k, does sound like something else.

 

Thanks, I have been told it is probably a fuel or exhaust issue. I am going to have it looked at by someone who will know what to look for.

 

when was the last time you replaced the fuel filter...? should be yearly.
This has caught me a couple of times, now I just automatically drop a new one in every spring...

Stu Aull
80GS
Alaska

 

Yep sounds like a fuel issue. Too many folks want to think its a cat issue. Cats do get clogged
sometimes but when they do they usually have symptoms like excessive heat at the cat and
it will be glowing red at night.