Poor Running at Speed
 

I am posting this message for my brother who lost the use of his computer today. He has a '71 1.7 with the stock FI. His problem is, after the motor has had a chance to warm up, the engine cuts out at 3,500 rpms and up. He did a complete major tune-up on the motor just recently. Any suggestions?

Do you mean cuts out and dies after it warms up and goes to 3500? Or dose it sputter and buck badly? Or will it refuse to go above 3500? My guess is either the dizzy or the thottle position sensor (TPS). If the dizzy broke an advance wieght spring or, like mine, became rusty and locked up. If the TPS is badly worn it usally bucks at a certain RPM but is fine above and below. I would pull out the dizzy, if you do it right you don't have to retime the motor upon installation. Then check the FI points and advance weights, and look for a worn out shaft and cam lobes.

P.S. The problem seems to be temp related. Better or non existant when cold, worse when hot. Could this be related to my alternator light coming on with the brakes lights?

Your symptoms point to floating trigger points in your distributer that should be replaced.