2002 5.7 mercruiser cranking problems

pd boat

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Jul 12, 2010
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I have had a cranking problem about 3 yrs now. No mechs. can tell me what the problem is.
Sometime (mostly after it sets for a few days) when I try to start it, as soon as I release the key it will try to start. Sometimes it takes 10 or 12 trys. I have installed a New Marine 750 cranking amp battery, new altanator and spark plugs and having the same old prob.
Can anyone tell me why it trys to start when you release the key??? Whats the Problem!!!!!!

Thanks in advance
pd boat
 

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Bondo

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Re: 2002 5.7 mercruiser cranking problems

Ayuh,... There should be the outside little wire on the starter powering the igntion while cranking....
My guess is, you Don't have that wire hooked up...
 

TiredoleBoy

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Re: 2002 5.7 mercruiser cranking problems

Wait are you stating it will attempt to start on its own when the key is released? In other words it cranks without the key being on or that it will not start until the key is released?
 

pd boat

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Re: 2002 5.7 mercruiser cranking problems

Yes your right...when you turn the key, engine will turn over like its suppose to but it wont try to start until you release the key. I've been told that the starting mechanisum must have at lease 11.9 amp for the engine to crank up. I have about 12.3 to 13 amps now with the new battery.

I have changed the key switch but it still does the same thing (sometime) if it has been setting for a few days.

SPOOKY!!!!!!!!!!!!

PD BOAT
 

TiredoleBoy

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Re: 2002 5.7 mercruiser cranking problems

Yes your right...when you turn the key, engine will turn over like its suppose to but it wont try to start until you release the key. I've been told that the starting mechanisum must have at lease 11.9 amp for the engine to crank up. I have about 12.3 to 13 amps now with the new battery.

I have changed the key switch but it still does the same thing (sometime) if it has been setting for a few days.

SPOOKY!!!!!!!!!!!!

PD BOAT

That sounds like the firing circuit. Perhaps the coils or the distributor. Check for spark when cranking bet it is not there.
Is there an assist solenoid and a safety switch on this?
 

pd boat

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Re: 2002 5.7 mercruiser cranking problems

That sounds like the firing circuit. Perhaps the coils or the distributor. Check for spark when cranking bet it is not there.
Is there an assist solenoid and a safety switch on this?

You may be right about the firing circuit or solenoid but I just put on new distributor and cap.

I don't know about assist solenoid but there is a lanyard switch. I don't think its any of these things...I'm thinking its in the computer system.. reason, sometimes it will start right up and sometimes it wont start until the keyswitch is released. The mech I had the boat worked on said that he checked firing, compression,fuel pressure,spark and for a while after I got the boat back from the mech it started great. Now its back to its same old s*#T!!!

pd boat
 

EddiePetty

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Re: 2002 5.7 mercruiser cranking problems

....as Bond-o has suggested, you should have a small wire running from the starter solenoid that powers the ignition when cranking.
If I am remembering Chevy starters correctly, the solenoid should have two large terminals (one for supply voltage and the other across the solenoil washer to turn the starter) and two smaller wires (one to receive voltage from the key and power the solenoid and the opposite to provide starting ignition).
 

Bondo

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Re: 2002 5.7 mercruiser cranking problems

If I am remembering Chevy starters correctly,

Ayuh,... Now a days, that's pretty much a Marine thing,....

Lotsa Chevy car starters lack the outside little terminal....
 

pd boat

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Re: 2002 5.7 mercruiser cranking problems

....as Bond-o has suggested, you should have a small wire running from the starter solenoid that powers the ignition when cranking.
If I am remembering Chevy starters correctly, the solenoid should have two large terminals (one for supply voltage and the other across the solenoil washer to turn the starter) and two smaller wires (one to receive voltage from the key and power the solenoid and the opposite to provide starting ignition).

Good point Eddie, but why will it start like its suppose to sometime and wont start until the key is released on other times? I don't know a lot about the newer engines but this one doesn't make sence to me..puzzeled!!

pd boat
 

Bondo

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Re: 2002 5.7 mercruiser cranking problems

I've been told that the starting mechanisum must have at lease 11.9 amp for the engine to crank up. I have about 12.3 to 13 amps now with the new battery.

Ayuh,.... I think that's Volts....
but why will it start like its suppose to sometime and wont start until the key is released on other times?

Corrosion in/ on the wire on the terminal We're talkin' about,..??
 
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