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2010 Mercury 50 ELPT EFI Starting Issue

R

RogerG

New member
This is a 50hp ELPT EFI 4 cylinder, built in 2010 according to the model/serial number sticker. This motor was brand new on my pontoon bought in 2011, no problems until now. Always used in fresh water.<br>
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I turn the key from off to "Run", everything beeps a couple of times the way it always has. I turn the key to "start", the starter motor turns just a little then stops. I see the bendix gear engage then gradually disengage indicating the starter motor is not applying pressure. If I let go of the key and try again, the same thing happens. If I hold the key in the "start" position for a few seconds, the starter will kick back in and spin the motor to start it right up. Very occasionally it will start up properly. Once running, the motor runs fine at all RPM, pushes the boat the way it always has, just keeps on going.<br>
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Battery is good, fully charged, and I get the same behavior if I have a battery booster connected up. All connections from battery to solenoid, starter, and ground are clean and good. All wiring in the motor is clean and dry, no signs of corrosion anywhere.<br>
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I thought it might be the solenoid, but a new one gives exactly the same behavior; signal wire connector is clean and tight. <br>
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I stripped the starter motor; brushes and commutator are in great shape, I cleaned out the small amount of carbon dust from the brushes. Same behavior.<br>
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If I move the shifter into gear, I get the beeps when I turn the key to "run", but nothing happens when I try to start. This is correct and expected.<br>
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The behavior is as if the signal to the solenoid is there momentarily when I turn the key to "start" but then goes away and returns after a few seconds if I hold the key in "start". I will test this theory tomorrow when I have someone to turn the key for me.<br>
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Is there some kind of sensor that can interrupt the signal wire to the solenoid in these EFI motors? Maybe I will have to break open the wallet and buy a repair manual with electrical component and wiring sections.<br>
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I found a very similar post in the forum dated a few years ago, but with no replies.<br>
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All replies and suggestions appreciated.<br>
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Today's experiment was to measure the voltage in the solenoid signal wire. Zero volts with key in "run". Momentarily 12 volts when key turned to "start" then drop to zero even though key held in "start" position, then a few seconds later up to 12, starter motor spins and engine starts. I noticed yesterday and today a slight fuel sheen on the water immediately after it starts, which evaporated/dissipated with the engine running. When the key goes from "off" to "run", I hear a very faint humming/hissing/whirring sound for a second or two from the engine which I think is the fuel pump. While the key is being held in "start" after the starter motor does its initial clunk, there is silence for a second or two, then the humming/hissing/whirring sound for another second or two, then momentary silence followed by the starter spinning and the engine starting.

So now I suspect an FI problem. Given the sequence of events, the noises, and unburnt fuel from the exhaust, maybe a faulty or dirty injector not sealing completely when de-energized, allowing pressure to fall and fuel to leak into an inlet port. The falling pressure causes a sensor/ECM to turn off the the starter solenoid signal until pressure increases again.

I need to pull the boat from the water for further investigation and repair.
 
I disproved my EFI theory, no sensors. In fact the wire from key-switch to solenoid is essential directly connected. So more head scratching.
 
@#%$&*!!!!! And then the light in my brain came on! Maybe the problem is not inside the black cowling at all! Quick test, key switch off, short jumper wire from the pos battery feed at the solenoid on to the solenoid signal wire: the starter spins the engine. That leaves only the key switch or the neutral safety switch. So now on my back under the console, bypass the neutral safety switch, reach up and turn the key, started right up, and shut it down immediately because I didn't connect the hose up to water inlet. Stand up, and try it again. Clunk then nothing. WTF? Again, clunk, nothing. Again, turn key slowly, starts up. Repeat, same. Turns out there's a sweet-spot at about 3/4 of the key-turn to start, turn all the way to the stop and nothing. Local store has a switch for less money than on-line.

Not hating my Mercury any more but kicking myself in the butt for not going after the simple stuff first.
 
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