Expert: chris Wethered - 5/21/2008

Question
I have two questions or problems with a 100 hp mercury outboard S/N:OC189024
#1- the engine starts but seems to be missing, it will only run for a few seconds then it shuts down.Last season the carburetors were rebuilt and the engine ran ok for most of the season.However ,towards the end the boat would start but would stall when put in forward or reverse. I looked at the plugs (champion L78VC) and they show ware on the inside edge on the electrode and the prong on the plug is burned off about 1/8" shorter than a new plug.I also cranked the engine over with the plugs out to check for spark and all four were firing,Three out of the four had a nice blue spark the other fired but seem to be a little on the weak side.
#2- I noticed no water coming out of the tattle tail when testing the motor.I took the lower unit off and replaced the complete water pump.I also replace the thermostat. I'm real sure I did this correctly, however I'm still not getting water out of the tattle tail when I start the motor. What I do notice is that when i have the flushing clamp around the lower unit suction ports,the water will initially leaks until I start the motor. Once started the leak goes away, indicating to me the water pump is working.Again no water out of the tattle tail!!
Do I have two problems or are they related? What do you suggest I check first? Do you need more information?
Thanks For your time, Best Regards Bruce

Answer
Hi Bruce

#1

List of things to check:

fuel tank either

empty - hose incorrectly installed - vent restricted or closed - hose crushed or bent.

Fuel filter plugged - fuel contaminated or stale - incorrect starting procedure.

Specified oil not used

Wrong spark plug gap - thermostat clogged or faulty

#2

I think you should remove the water pump and make absolutely sure you put it back correctly. If the problem persists let me know.

Chris