Mariner 1998 135 hp hard starting amp idling

"I have a 1988 135hp v6 Mariner outboard oil injected. When cold its hard to start & won't idle properly. When off idle at full throttle it takes a while to get up & go, when backing off to idle it stalls."

"David, sound like classic fue

"David, sound like classic fuel problems.

So if the gas is new (less than 2 weeks old) and the sparkplugs are less than 2 years old and not fouled, troubleshoot the fuel system.

The crappy cold start/poor idle could be related to a bad thermostat, but more likely a clogged fuel filter or partially clogged carbs.

I would inspect/replace the filter as necessary and then try running some of Merc's "Powertune" or SeaFoam through the system to see if it's just carbon/general "cooties" in the system, but if your symptoms persist the carbs need to be pulled, disassembled and cleaned - and possibly rebuilt.

Additionally, the stalling when backing off could also be related to restricted low speed carb jets or a clog in the float needle valve(s), both of which would be corrected with a carb cleaning/rebuild..."