496HO, fast beep and voltage drop
 

Need help with a buddys boat. 35 fountain twin HO's. Starboard motor runs fine. Port motor wont start. When you turn the key to the run position the warning indicator beeps continually very fast, the warning lights flash fast also, the gauges(tach, gps speedo) jump all over the place, you can hear the relays on the motor clicking wildly(same pace as the warning beep). The motor cranks real slow. Brand new batteries, clean terminals. 13 volts shows everywhere in the boat with key off. Only 8-9 volts with key on. Fuel pump doesnt run. We checked all the grounds, swapped ECU's and all the relays from motor to motor. Still no change. We disconnected the alternator. no change. We added a temporary ground from the battery to the block. Still no change, we wiggled wires all around the boat no change. We checked the merc engine harness connector, clean and dry. This was the first attempt to run the boat this year. Interestingly it did start right up on the lift the first time and sounded fine. As we idled out when we went to speed up a little the motor was missing. When we took it ouf of gear it was barely running. We shut it off and barely got it running again. It would not rev hardly at all. Then the beeping etc started. we have a couple times got the beeping to stop(not sure how) and the fuel pump ran, but it still would barely crank over. We shorted across the solenoid with the key off and it still cranks slow. Oh, yeah the starter is less than a year old. It really seems like a ground issue and I think we are going to disconnect clean and re tighten any grounds we can fine. Also gonna disconnect reconnect starter wires. Anyone experienced anything like this?


jadento

In most cases it is the ground, but since you added another ground and there was no charge, I would look at the positive cable. Crank the motor over while feeling the positive battery cable and see if it gets warm. Might be between the battery to bat switch to starter

What did it do with the old batteries?

It had the old batteries in it when this started. They were 4 years old. We put two new ones in today.

Good thought on the positive cables and checking for warmth. We were wiggling wires all over trying to see if it would do something and we didnt feel any that felt warm. Didnt mess with the positive cables much though.

I’m wondering also if it could be the starter itself? Though not sure about that because the starter does turn. It’s strange that when it does stop the beeping every now and then randomly that it does the full beep and you hear the fuel pump prime.

^^^Boat owner

Where was the boat stored? Was it struck by lightning? Man that is weird! This is a new level of WTF.

You need to start putting the voltmeter in different places at starter, relay and ecu. My 496's do crazy chit like this when the batteries get old - Im wondering if corrosion (somewhere) isnt getting enough volts to where they need to go.

Have you considered pulling both the ignition switch(es) and kill switch to check for voltage? I chased a problem last year back to my ignition/key switch had corrosion.

The boat stayed on the lift outside all winter(covered of course). No signs of any critters having been in the boat either as I did consider that. We did use a volt meter all over. Pretty much everywhere it drops to 9-10 volts with the key on. we have checked connections and voltages at ignition switch, helm breaker and kill switch. We plan to go back and pull all the grounds(really only a couple) and remove clean re-tighten them. I may even start taking resistance measurements across wires. Also, we are going back to the starter and removing, cleaning re tightening wires. Lastly we already have a new alternator to install so I think we will get that done also. TitanBry77 and I both are fairly confident its something simple/stupid were just missing it.

jadento

Just to follow up. We started tracing positive wires as we had been focusing on the grounds. The terminal on the starter for the main power wire from the starter up to engine was cracked, almost broke in half. So there was a connection but could not flow current. Once it was found and wiggle it fell apart. Also the arcing melted the fusible link on the starter. New terminal and fusible link and its been good to go.

Our assumption is it was corroded(and got worse over the winter). It was good for the first start up but the vibration of the running motor quickly finished it off.
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