what is the check for weak spark?

[bob johnson]

my motor has been slow to start on these bitter cold mornings... I know that the priming system is usually to fault... and it takes good bulb pressure and holding the key in for 10 seconds or more and or pumping it. 5-10 times before each time i try to start the motor..

one problem is that as soon as the motor tries to fire, the starter is pulled off the flywheel..

but usually it has started in a minute to three..

but this weekend it took me 30 minutes!! and i pulled the plugs and they were wet!!!

but the motor doesnt eve seem to want to fire unless i prime a lot...

the plugs were a little black( dark really) so i replaced two and clean one( V4)

I have this IDEA that maybe the spark isnt that powerfull maybe.

I know its bad but i used a few squirts of starter fluid....thinking once it fires the fuel will deliver the needed oil pretty soon..

anyway....it wouldnt start with that!!.....so i am going to look into what makes a strong and a weak spark


any help?

thanks

it is a 1995 115 ocean runner..(v60 dgree)

and it was 19 degrees out when trying to start

side note...once this motor starts for the day...it will start every time after that easily...even if it remains the same temps.... and i have the motor off for 3 hours....

bob

 

[64osby]

Re: what is the check for weak spark?

Search for a spark tester and lots will pop up. Many make there own and you can buy one at HF or many auto stores.

Not sure of the gap test setting for your motor, should be at least 3/8". Older motors were about 1/2".

You said you replaced two and cleaned one plug, and reading into what you posted it still wouldn't start.

Test your spark and see what you have.

Have you tested the compression lately?

 

[bob johnson]

Re: what is the check for weak spark?

havent check the compression lately.... and i do have a auto zone spark tester.....but its just a gap tester... i wasnt sure if that would be an adequate test.

i am going to put 2 more brand new plugs in....

I usually keep four spares in the boat

bob

 

[emdsapmgr]

Re: what is the check for weak spark?

A compression test is a good idea. It validates the fact that the engine is worth putting some $ into... When cranking the engine to start, and finding wet plugs-it's likely that you have poor/no spark.

 

[boobie]

Re: what is the check for weak spark?

Your spark should jump a 7/16" open air gap on a spark tester. When starting. Pump the primer bulb until hard, then turn the mtr over while pushing the key in until the mtr fires. When it fires release the push on the key. That is the correct way.

 

[bob johnson]

Re: what is the check for weak spark?

well for sure i prime the bulb in the gas line until hard.... then the way to start my style motor , I learned was to puch the key in for 7-10 seconds...or pump the key in 7-10 times....( i do both alternately) and then try to start the motor.....

the motor would never start if you didnt push the key in for a period of time or several time PRIOR to cranking the motor over...

another issue might be that the starter dissengages awful quickly if the motor just seems to try and fire.... and you hear the whimnning of the bendix spinning( no engagment with the flywheel any more),

very seldom can I crank the motor over for any more than 4-5 seconds.... after 2-3 seconds the starter gear withdraws and the bendix just spins....

every ONCE in a while the motor will crank and crank......i think it is because , once the motor tries to fire...the starter gear dissengages

strange...but up till now i had been dealing with these issues and still getting the motor started in decent time...

bob