280 Idle Adjustment ?

[KeithRichards]

Have the idle screw set where the motor runs @ 750- + rpms in gear. But it feels like it's hitting on about 4 cyls and is running rich on the pyro. About 400 on the starboard and 250 on the port. Can give it some gas to 1000 rpms and it smooths out and runs 600 on both. Was looking at the TPI on the horn and it looks like it can be adjusted there.

Which way do I turn the TPI ?
Or leave it alone and give up on a smooth idle ?

Thanks Keith



http://www.flex.net/~krich/280.jpg

[Euroski]

Boy... have I been down that road before! Here is what you need to do and do. First of all the ECM controls the idle to just about 900-1000rpm in or out of gear. Remove your throttle linkage and set the airgap at the throttle plate to .005-.006" of an inch. Next set the TPS voltage to .80-.82 volts! You can do this 2 ways, one is with Merc tester if you have one. But I use a digital volt meter and connect the black to engine ground and red to the lightblue/white wire on the TPS. I use a safety pin to go into the wire. Set this voltage with key on and engine not running. After you move the TPS open and close the throtle to make sure the voltage stays in that range. If the voltage gets above arounf .86 volts then the engine will NOT come back to an idle and hangs around 1500-.


Let me know how you make out

[KeithRichards]

Holly Smoke !

I would have never thought of that. Guess that's why they make service manuals.

Looks like a 280 is not made to idle slow. It was idleing over 900 rpms till I backed it down. Thought that was too fast. I'll turn her back up. But I will check the settings.

Thanks for the info. Keith