How to perform compression check???

[Adeal]

I have a 1992 75 hp Mariner and am having trouble getting it to crank. I have read some forums and realize I need to change my spark plugs out and maybe perform a compression check? Is this this the same compression check done on car engines? Can you use the same psi gauge for a car and my outboard motor? I was going to just rent one from the local auto store.

 

[saumon]

Re: How to perform compression check???

Do yourself a favor and buy one. They're like 20$.

As for the procedure: remove all three plugs, open the throttle, flip the kill switch, screw the gauge in hole #1 and then crank the engine for 3-4 sec. Note the reading, reset the gauge and repeat for the others two holes.

Just out of curiosity, are you having trouble getting the engine to crank or to start? If it just crank slowly, it's probably related to the starting circuit (faulty starter/bendix, loose/corroded connections or weak battery).

 

[Mi duckdown]

Re: How to perform compression check???

When you say cranking, does that mean the starter Rotates the flywheel.
Or the engine won't fire.
Engines crank over, some don't fire.????

 

[Adeal]

Re: How to perform compression check???

I guess I should say start. The started engages the flywheel but it wont start unless my dad manually pulls on the (throttle lever?) not sure what its called, on the side of the motor which opens the carburetors and it starts right up..not sure why? any ideas? I replaced the started solenoid a few weeks ago because It would not crank at all and that seems to be fine now.