Problem Starting, Can't Trouble shoot

[lightningfastsvt]

I have a 2004 Merc 115 4 stroke motor. The boat has been sitting for a few months. I went to crank her up today, and she wouldn't start. Wierd though. The boat would start with the key turned (starter activiated), but as soon as I let go of the key, the motor died. I tried this several times, even using the throttle. No luck. I held the key for 10, 15, 20... seconds and the motor ran strong, but as soon as I let go of the key, it died every time. Any ideas on what this could be? Does not seem mechanically logical...

 

[Laddies]

Re: Problem Starting, Can't Trouble shoot

Check your kill switch

 

[lightningfastsvt]

Re: Problem Starting, Can't Trouble shoot

Are you referring to the "Run" switch located on the throttle? If this not the solution, could it be a faulty/loose ignition wire?

 

[Laddies]

Re: Problem Starting, Can't Trouble shoot

I am asking about the tether switch, if it's not that, it sounds like the ign. switch or wire problem

 

[Silvertip]

Re: Problem Starting, Can't Trouble shoot

I'm not sure about the wiring on that motor but an electric fuel pump has a safety feature that kills the fuel pump if the engine quits. Normally this is done with an oil pressure switch on a four-stroke motor. Therefore, there needs to be a bypass around the oil pressure switch when starting so the pump can run until the engine builds oil pressure. Since everything seems to work with with key in START, and fails when released, that would indicate the fuel pump relay is not being engaged to keep the engine running. If the kill switch isn't the problem, look at the oil pressure switch wiring and the feel the relay to see if you can feel it cycle.