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Tan
Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 10901
Experience:  40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
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I have a 1977 mastercraft 190 prostar. it turns over very slow.

Customer Question

i have a 1977 mastercraft 190 prostar. it turns over very slow. battery is good. what else do i check.the boat is sold and i got to have it ready
Submitted: 2 years ago.
Category: Boat
Customer: replied 2 years ago.
i have the boat here with water hooked to it what do i need to do
Customer: replied 2 years ago.
(Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Customer: replied 2 years ago.
amos(###) ###-####
Expert:  Tan replied 2 years ago.
Hello. My name is***** you have a volt meter to do some voltage tests?
Customer: replied 2 years ago.
yes
Customer: replied 2 years ago.
what do you want me to test
Expert:  Tan replied 2 years ago.
We need to test the voltage at the battery cable connection on the starter when cranking. What is your voltage reading?
Customer: replied 2 years ago.
8.0
Expert:  Tan replied 2 years ago.
Ok now I need you to test the voltage at the battery when cranking. What is your voltage?
Customer: replied 2 years ago.
8.4
Expert:  Tan replied 2 years ago.
The battery must maintain 9.5 volts to start the engine. Is this a new battery? Can you put the battery on charge and test the voltage again?
Customer: replied 2 years ago.
i have jumper cables hooked to it 10.1 still turnig slow
Customer: replied 2 years ago.
at the starter with cables hoohed up 7-9
Expert:  Tan replied 2 years ago.
The starter is bad. It's requiring to much amperage to crank the engine over. With 10 volts that is enough to crank the engine. So you have the voltage leaving the starter as the problem.Replace the starter.
Customer: replied 2 years ago.
the starter is moving from 7.5 to 9 still bad
Expert:  Tan replied 2 years ago.
What happened to the 10 volts? If the voltage is jumping around when cranking the starter is bad.
Expert:  Tan replied 2 years ago.
Is the starter top mount or bottom mount? The top mount starter RA122009, bottom mount RA 122015
Customer: replied 2 years ago.
i took it to get a new one and they said the starter is okay. they tested it there
Expert:  Tan replied 2 years ago.
How did they test it? You can't test a starter with out putting a load on it. Did they connect it to an engine and try cranking the engine?Bench tested don't work. If you are getting sufficient voltage to the starter and it won't turn the engine over the starter is bad. The only other possibility is the engine itself is got an issue. Has the engine been sitting?Pull the spark plugs out do a compression test.
Customer: replied 2 years ago.
how do you do a compression test
Expert:  Tan replied 2 years ago.
You will need to install the starter get a compression gauge. Remove all the spark plugs and screw the compression gauge in to each spark plug hole crank engine over at least 4 times read compression gauge. The starter should turn engine over with spark plugs out. Test each cylinder this way post back with readings. If the starter doen't turn engine over with plugs this just verifies the starter is bad or the engine is binding due to rust or internal engine issue or lastly possible transmission issue. Has the boat been sitting unused for an extended period of time?
Customer: replied 2 years ago.
I think I got it. I bough a truck starter it is turning the wrong way
Expert:  Tan replied 2 years ago.
What is your question here?
Expert:  Tan replied 2 years ago.
You can't use automotive starters on a marine engine. They are an explosion hazard.