Low compression?

[guppy]

Working on a 4 hp Johnson serial #j4rdhesr, started loosing power idling poor. Found low water flow due to clogged intake on water. Side plate on exhaust leaking water and exhaust. Repaired these issues and ran it on water, low power. Ran compression test 30 psi on first pull, maxed out at 105 psi by 5th pull. Does this seem low? Cleaned carb and checked fuel lines. Fuel primer bulb stays hard when running off idle but runs out of fuel at idle, any ideas?

 

[kimcrwbr1]

Do a spark gap test using a open air spark gap tester it must jump a gap of at least 7/16 inch on both plug wires. That ignition was sensitive to overheat being under the flywheel. If the spark is weak get the CDI upgrade and put the module on the side of the motor.
http://www.marineengine.com/newparts/part_details.php?pnum=CDI113-4488

 

[kimcrwbr1]

http://www.marineengine.com/newparts/part_details.php?pnum=OMC0393088
You can allways just rebuild the fuel pump for cheap also just to eliminate variables and replace fuel lines to eliminate that variable all part of preventive maint. The instructions come with the kit carefully take it apart and lay the parts on a clean bench little parts disappear quickly.

 

[guppy]

Thanks for the reply, Check spark with open gap tester, jumps 1/2 inch with no problem. fuel pump now quit working, might be whole can of worms, Found outer thick rubber piece had a hole in it. Still might have ign problem, Also wondering about compression, just seems really low to me

 

[kimcrwbr1]

Rebuild the fuel pump and replace the fuel lines then go from there. If your getting 100 psi with a pull start it should run just fine. You can replace the head gasket for cheap also just for giggles. That will give you a good look at the cylinder walls.

 

[Boobie]

Do a good de-carb on it. That may help. JMO

 

[johnnygjr]

Keep us posted guppy