1985 merc 9.8 trouble shooting

[Flyguy39]

I acquired a boat and merc 9.8 from a trade. However the merc wasn’t running. The guy said he was able to get it to fire up but wouldn’t idle. I haven’t been able to get it to fire up. Seems to have decent spark and looks like it’s getting gas. Any one have any experience with these engines I don’t know all that much about outboards worked on dirt bikes mostly.
Any help would be great!
thanks.

 

[QBhoy]

First thing to do, to rule out anything serious or to see if it’s worth carrying on with the simple stuff....is to do a compression test on it. Rule out anything serious.

All being good...get the carb off it, clean out...new plugs and fresh fuel mixed at 50/1. See how she goes. Not much else to go wrong. Failing these common things..look at the pump diaphragm.

 

[racerone]

Wiring insulation can be bad on these and crumbles off.-----Top crankshaft seal is often loose on these.----Top crankshaft bearing housing can work loose.----O-ring on driveshaft is often forgotten.----Water pump impellers are not robust and need regular replacement.