How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Dominick Your Own Question
Dominick
Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
14379177
Type Your Boat Question Here...
Dominick is online now
A new question is answered every 9 seconds

Got a mercury 40 outboard motor i have 120 psi compression

Customer Question

got a mercury 40 outboard motor i have 120 psi compression all four cylinders have spark and fuel acts the the timing is off checked fly wheel key its ok any ideas
Submitted: 2 years ago.
Category: Boat
Expert:  Jason replied 2 years ago.
Hello my name is ***** ***** am I speaking with? What makes you think the engine has a timing problem? What exactly is it doing?Also, can I get the serial number on the engine please.
Customer: replied 2 years ago.
my name is ***** ***** engine has spark compression and fuel when trying to start it will just turn over every once in a while it will kick
Expert:  Jason replied 2 years ago.
Hi Sandy.Have you tried any starter fluid down the carbs?Do you have a timing light to check timing?
Customer: replied 2 years ago.
i tried starter fluid both carb and cylinders no on timing light
Expert:  Jason replied 2 years ago.
Pull all the spark plugs out. Stick a screwdriver down the top plug hole. Turn the flywheel slowly by hand until you can feel the piston come up to the very top of its' stroke. When it's at the top. Is the 0 mark on the flywheel lined up with the timing tab?
Expert:  Jason replied 2 years ago.
Is that something you can do now?
Expert:  Jason replied 2 years ago.
Also, how did you check for spark exactly, there are right ways and wrong ways to do it.
Customer: replied 2 years ago.
0g224602 serial number timing mark is on 0 with piston up
Expert:  Jason replied 2 years ago.
how did you check for spark exactly, there are right ways and wrong ways to do it.
Customer: replied 2 years ago.
took all plugs out put plug on side of engine all four sparked
Expert:  Jason replied 2 years ago.
Got it. That is not the correct way to check for spark. To properly check it you need a spark tester set to 7/16ths on an inch, and the spark needs to jump that gap. Click this link below to get to a youtube video. This explains how to check for spark. Fast forward to the 3 minute mark. https://www.youtube.com/watch?v=eSmNMWTDtZE
Customer: replied 2 years ago.
used a spark testor forgot i had and all still have good spark
Customer: replied 2 years ago.
any other ideas
Expert:  Charles replied 2 years ago.
Hello, my name is ***** ***** you still need assistance with the engine?
Customer: replied 2 years ago.
yes i do
Customer: replied 2 years ago.
i have spark compression and fuel but the engine will not run
Expert:  Charles replied 2 years ago.
Check the fuel for water. I think that I saw where it is new, but you can still buy water at a gas station.
Customer: replied 2 years ago.
i sprayed starter fluid in the spark plug holes still will no trun
Customer: replied 2 years ago.
acts like it is firing at wrong time just poofs once in awhile
Expert:  Charles replied 2 years ago.
Do you have a multimeter?
Customer: replied 2 years ago.
yes i do what should i test?
Expert:  Charles replied 2 years ago.
Take out the plugs, measure the resistance from the cap to the threads. Then from the cap to the center electrode. hat do you get?
Customer: replied 2 years ago.
0.00
Expert:  Charles replied 2 years ago.
From where to where?
Customer: replied 2 years ago.
cap to electrode
Customer: replied 2 years ago.
there are new plugs
Expert:  Charles replied 2 years ago.
Still have the old ones?What plug do you have?
Customer: replied 2 years ago.
no
Expert:  Charles replied 2 years ago.
Was that on both plugs?Which plug do you have?
Customer: replied 2 years ago.
this is a four cylinder alll new plugs new gas they all fire 120 psi compression im stumped
Expert:  Charles replied 2 years ago.
Does the meter have a max or a hold button?

Related Boat Questions