Logo
FULL SITE MENU

Merc 500 Hard to start.

B

Bob in Tennessee

Contributing Member
After several years of great service my 1977 50 HP has been getting harder and harder to start. She is electronic ignition. I am going to start with new spark plugs. What are your recommendations? If that doesn't improve things then i will do the compression test ect.
Thanks
 
These motors are notorious for bad / rotted wiring.---So inspection is required.------First check compression.-----Simply because you need to know condition of motor before spending the beer tokens !!----Second is a maximum spark test.-----Does spark jump a gap of at least 3/8" on a test device ?-----Sparkplugs last for years and years on these.-----You have replaced the water pump impeller ??-----Simply because these motor often do not have a shutdown system or an overheat warning horn.-----It could overheat and run till it destroys itself.
 
IF that Motor has chokes, be sure they are sealing tightly. (The black plastic ones trend to warp and leak over the decades.) If in stead it has an enrichener, remove the hose to the block and see if gas flows freely with the "choke" on.

Jeff
 
Replaced impeller earlier this year. I get a stream from pee hole. I will ck compression and spark tonight. I will also ck to see if it has enricher. I am not familiar with this but I should be able to find it by looking at my parts manual. I have had bad wiring experiences in the past with Mercury and I will ck these out as well. I was just hoping it was something simple because I enjoy fishing more than mechanic-ing at my age. The symptoms are.....hit choke and turn ignition key and it spins as much as ten seconds before starting. When engine is warm it should fire right up with no choke but often it doesn't. I have to engage warm up throttle to get it to start and often it will start and sputter out. Then I have to repeat using choke.

Earlier this year it would fire right up as it should and issue has been getting progressively worse. it is not something that happened all at once.
thanks you guys!
 
I'm sorry fastjeff I just understood your suggestion. What I think you are saying is it either has an electric choke (which it does) or it has an enricher. I will ck choke plates but I think they are metal.
 
Did compression test. 125-125-120-125
spark jumps 3/8 gap with spark tester
primer bulb firms up with no visible leakage at fuel pumps or carbs.
Cleaned plugs and engine started after 5 second spin. Seems like it should start easier. I will have it out on the Tennessee River Wednesday and see how easily it starts after it warms.
Thanks for everyones help.
 
Back
Top