cut out, then no beep when turning ignition key to start boat

[jeff]

morning guys, i have a 2002 28scr 7.4 , i was out going slow the other day, but when i try to go up on the plane she strained a bit then i got a beep from the engine i believe, like a warning beep,, that went away about 5mins after i backed off the throttle, so i cruised in and parked her ,, so i go to take her out the water today but i have to cruise a few miles to the slip,, 10 mins into the journey the engine shut off,,, the instruments were still working and the engine still cranked over,,,, but would not start ,,but i notice that i didnt get the two long beeps i get when i first turn the key like i do every other time,,, she kicked over about 15mins later,,,,, but the instrumentals were not working this time and still no beep from ignition but she started ,,,, weird

any ideas guys?
thanks
jef

[pascavone]

Sounds like a low oil warning, which could be from water in the engine.... look for milky foam under the oil fill cap.

also, a high temp alarm if your raw water pump is blocked our worn out.

If the gauges, are dead, then there is a short, and the harness is feed from your 80 amp fusible link that sits on top of the start positive post.



its a pain to bend your head down under a 7.4, but if its melted that that where your start looking.

NEVER RUN ON BOTH BATTERY'S.... this pushes 24 volts upto this fusible link, and will melt it......

this link stop the voltage from frying your wiring.

the link will cool down and then run the boat again....

[jeff]

[QUOTE=pascavone;26826]Sounds like a low oil warning, which could be from water in the engine.... look for milky foam under the oil fill cap.

also, a high temp alarm if your raw water pump is blocked our worn out.

If the gauges, are dead, then there is a short, and the harness is feed from your 80 amp fusible link that sits on top of the start positive post.



its a pain to bend your head down under a 7.4, but if its melted that that where your start looking.

NEVER RUN ON BOTH BATTERY'S.... this pushes 24 volts upto this fusible link, and will melt it......

this link stop the voltage from frying your wiring.

the link will cool down and then run the boat again....



thank you very much im gona look now

[mcoffey]

Originally Posted by pascavone

NEVER RUN ON BOTH BATTERY'S.... this pushes 24 volts upto this fusible link, and will melt it......

I am sorry Pascavone but this is not correct at all. You have 2 batteries connected in parallel which keeps everything at 12V but will double the Amps that can be output to the connected devices.
The only way to get 24V with 2 batteries if connected in series (positive from one connected to negative of other).
What melts wires and fuses is too many amps. Amps are a funny thing as they are not always there.
So you have a 12V battery that is rated at 950CCA, it is not always sending out 950 Amps.
Amps are pulled from the devices and are relative to the voltage supplied. So if you have a device that needs 10A at 12V and you can only provide it 6V, it will pull 20A.
So with 2 batteries connected, you will only ever melt things if something is drawing too much amps and the wire or fuse is not capable of carrying that load.
About the only thing on a boat that is even remotely capabable of that is your starter. If your batteries are weak and set to both and you keep cranking and cranking while under low voltage, your amp draw will just keep going up and up the longer you crank (heat generated by starter increases draw as well as lowers voltage on batteries which increases load).

[pascavone]

hi mcoffey,

yes, i think i got the amps, volts mixed up last time this came up.

bottom line is, the fusible link is an 80 amp cut out...... for $32 new.....

lesson is : melting BAD.....

as you know a short will melt a post off a battery..... ( ask me how I know this...;(

So, a short will melt, spike, amps, volts, and weld things together...... not good around gasoline.

And yes, Mercruiser manual says, "never run on Both, except for starting as you noted.

[mcoffey]

Yes, shorting is very very bad and as you said, things melt
Most battery load testers actually do just that as a high load test, they put a dead short (or as close to dead short as possible) which draws the most amps. If the battery survives 10-15 seconds of that, it is most likely a good batery. I have even seen failing starters cause such a high amp draw that it caused the starter solenoid to stay closed and the engine continued to crank after key was off. This causes the battery cables to start melting along with the negative post on the battery. Seems that starter got dunked a few week prior as the marina forgot to put the plug in the boat and water made it up just above the starter (PCM 351 engine). A few solenoids later (we were convined the solenoid was faulty) we finally replaced the started once the dunking story was told and all was well again.

Nothing like watching an engine crank over by itself with the battery underneath a front seat and starting to glow red

[ss3964spd]

Thanks for clearing that up MC......

Jeff, if the engine is still cranking over then forget about the fuseable link - that isn't your problem.

At this point I think it's also a stretch to suspect water in the oil causing a low oil pressure condition, which would cause an engine shut down. It's possible that the engine DOES have low oil pressure, which would cause the ECM to shut it down, but that doesn't explain the "strain" to get on plain condition you described, and also doesn't explain that you were eventually able to restart it and continue on. Low oil pressure problems don't go away by themselves unless the oil level in the pan is low.

My first guess is that you've got an over heat condition (warning beep that went away after you backed off) or possibly you've got an ECM issue (no gauges, and no pre-start warning beep). Only guesses though, you might do well to have a Merc mechanic plug into the ECM and pull the codes.

Dan

[jeff]

thank you Dan, i will get my mechanic to check all those things