5.0 Merc turns over but won't start - Maxum Boat Owners Club

M.T. Pockets · 07-13-2005, 04:17 AM

I have a 5.0 in my 2400 SCR and it sometimes cranks but won't turn over. I check the carb and it is flooded. What is the chance that it has to weak a battery. Someone told me to get batteries with higher CCA's.

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Rich

Maxum2300SC · 07-13-2005, 04:05 PM

Sounds like a weak or intermittent spark. how old is the coil, when was the cap/rotor changed last? plugs? wires? what ignition do you have? Thunderbolt IV or V?

3388sam · 07-13-2005, 07:09 PM

Quote:

it sometimes cranks but won't turn over

Do you mean the engine is turning but won't start or it's not turn at all?
If the battery is so low it barely turning the engine over it will drop the battery volts below 12v and it won't have enough to create a spark.

M.T. Pockets · 07-14-2005, 11:19 AM

Im sorry it turns over but it won't get a spark. Everything is new as is the Engine, as of last spring. I used the boat all of last year with out a problem. I had it in a slip with shorepower always hooked up, this year I have it trailered and no shore power to charge the batteries. I checked the batteries volts and they are above 12v and was wondering how do you check CCA if it is possible.

Rich

3388sam · 07-14-2005, 06:28 PM

CCA= Cold Cranking Amps.(only has to do with engery to turn the engine over) Can only be tested with a load tester, not something the shade tree mech. has.
You can test the battery with a volt tester while you are cranking and see if the battery has enough reserve to supply 12v while turn the engine over.

But usually if the battery turns over the engine easily it is fine!

If you are not getting spark you'll have to look at the rest of the ignition system- Might be a good time to invest in a service manual! Can get costly replace marine parts!

Maxum2300SC · 07-14-2005, 07:21 PM

here is an article on troubleshooting the TBIV ignition system, the V is basically the same

my problem on mine was a bad pickup in the distributor. ICM rarely goes

3388sam · 07-14-2005, 07:56 PM

Mt just what you needed above. I have a neighbor stared replacing everthing (don't know what it cost him) but in the end brought it in and it turned out to be a bad oil sender. $10 part on his boat,it wasn't a Maxum . If there was no oil pressure it interupted the igntion and would not start.

Maxum2300SC · 07-14-2005, 08:38 PM

Quote:

Originally Posted by 3388sam

Mt just what you needed above. I have a neighbor stared replacing everthing (don't know what it cost him) but in the end brought it in and it turned out to be a bad oil sender. $10 part on his boat,it wasn't a Maxum . If there was no oil pressure it interupted the igntion and would not start.

yes, try disconnecting that too to see if she will start. Pretty sure its port side of the engine in the lower back. Also check your kill switch.

3388sam · 07-15-2005, 12:32 AM

One other place to do a quick check is the Kill switch by the throtle. I've seen that one a few times as well. Gets bumped into, cranks all day nothing. Your just about ready to tear the engine apart and oops there it is! :shock: