Working on a 87HE, tops out at 80mph with pedal to the floor. Suggestions?

 

The '87 has two ignition coils. If one of them is not working then engine RPM will be limited.

Check the coil that is mounted in front of the radiator. Make sure it is good and that its wiring harness is properly connected to the coil in front of the throttle pedestal.

The two coils are wired in parallel (+ to + and - to -). There is no high voltage wire coming out of the front coil. It should have a rubber cap on it.

Mark

 

If the coils are OK then check the vacuum advance in the distributor. It could be stuck and not advancing as needed.

Make sure the mechanism is lubricated. Work it manually to ensure is operates smoothly and has full range of motion.

Apply vacuum to the vacuum module and ensure it is working. Its a common failure point.

Mark

 

If all of the ignition checks out then you need to look at fuel. Low fuel pressure (regulators), clogged filter, clogged swirl tank etc.

Might also check the vapor recovery system and insure the fuel tank has proper ventilation. If the tank vent is clogged it will restrict fuel flow.

Mark

 

At 80 mph what is the rpm?

 

Catalytic converters may be clogged.

 

Agreed. Its the next thing to look at after you check the ignition and fuel.

I have one of those inspection cameras from Harbor Freight;

High Resolution Digital Inspection Camera with Recorder

If you remove the oxygen sensors you can use the camera to look inside the front converters. They are the most likely ones to be melted/damaged.

Mark