Logo

Please help!! Not running mercury 8 hp outboard

xroyalty

New member
Hey guys i need your help, bought a boat with the motor not running. It is a 1989 mercury 8 hp.

I’ve done everything i could to get it running i just can’t figure it out. Motor wasn’t running at all when i bought it.

First thing i did was bought a new gas tank and filled it with new gas and oil. It started up for a quick second then didn’t start at all.

Next thing i did was take out the carburetor and notice the gasket was ripped and half so i figured that was the issue.
Bought a new carb kit and replaced all gaskets, still no start.

The only time i could get the motor to start was sprayed carb cleaner and it would run for about 2-3 seconds and die unless i kept spraying it. (I know carb cleaner isn’t good for it so i stopped spraying it)

Next thing i did was replaced all fuel lines in the engine and the fuel hose that goes from the tank to the engine. Still no start.

After removing the carburetor and gas lines so many times it doesn’t start at all now even with carb cleaner.

I know that was a lot but I’m just trying to tell you guys all my steps.

Please if you guys have any suggestions or tips i would appreciate it!!!
 
Test the compression - 90 psi or over is good

Test for spark - one of those spark testers from a discount auto place is sufficient

CHANGE the sparkplugs - replace them with NGK's only, don't cross ref to Champion. The ignitions on these don't like Champion and are somewhat finicky about old plugs (I own three of this platform and they get new plugs every second year).

The carb probably needs a "cleaning" and possible rebuild if it's been sitting around and wasn't running when you got it. A rebuild kit (can) also include the fuel pump kit - worth changing as well.

An impleller kit is also in order. There are at least three different levels of kits available. You probably don't need the one with the new metal base but the mid-level kit (impeller plus a few extra parts) would be the one I would go with.

Get a Seloc's manual - they are "good enough" for the backyard mechanic working on the 6/8/9.9/15 horse 2 strokes - will cover everything you need to do.

These are exceptionally well built motors and a bit of rehab could potentially bring it right back (I own an 86 (9.9), 87 (9.9) and 91 (15) from the family).

It is getting old enough that the coils might need changing - it is a common (issue). Wipe them down well and check for cracks or even spider cracks. If suspect at all, change them out. I would go with Sierra coils in this case (not OEM). The Sierra coils are less expensive AND more powerful which really helps with the idle.
 
Back
Top