2015 Honda 50HP suddenly dies (sporadically)

[Michawilden]

Hi All,

A new to us honda 50 hp 3 cilinder Efi runs good and starts good. We have had it for one year now. A couple of times we had a problem that the motor suddenly dies, or suddenly does not start. Besides that it runs and starts great. This does not happen all the time but it looks like it happens after we let it cool down for half an hour. Then it does not start. It cranks good but does not start. When it dies on the water it is the same. After some while, it will start again. And,( I think) It always starts when the motor is completely cold after a day or so. Also independant from the weather.

My first gues was a problem with the kill switch circuit. I've used this wiring diagram: http://cdn.powerequipment.honda.com/pe/pdf/pubs/tm048pdf.pdf
Not the same motor but I thought that the colours would be the same.
I thought that maybe the kill switch wire ( black / red ) might make a contact somewhere, killing the engine.

I've made a switch in the motor on the black / red wire to the remote control so that I can test the motor when it dies on my. By flipping the switch, the black/red wire is open. That way I know if it is a kill circuit problem or maybe a motor problem ( sensor / ECU).

When I installed it I tested it. Flipping the switch to closed, the kill switch and the ignition switch both work. I can kill the running engine.
Flipping the switch to open, the kill switch at the remote control does not work anymore. Motor keeps on running. But I can still kill it with the ignition switch. That is not correct I believe? The ignition switch should also be connecting the black/red wire with the common ground.

Does anyone have a hunch of what might be goin on with the engine? My next step is opening up the remote control and see in what way the ignition switch is connected. But if this solves the problem

 

[MattFL]

Before you go taking things apart, try to figure out what's missing. You need spark, fuel and air/compression to run. First figure out which one is missing, then figure out why. It sounds mechanically OK so compression is most likely good, skip that one for now. Get it to the point where it won't start or won't re-start, then the easiest thing is squeeze the ball in the fuel line and make sure it's full of fuel, then try again. Did that fix it? If yes then figure out why it's running out of fuel. If not, then next check for spark. Remove one of the spark plugs, put it in the boot and touch the motor with the silver part of the spark plug, have someone turn the key and look for a spark. You should see and hear an obvious spark. If there is none, THEN start figure out why. If there is spark, then next would be making sure the fuel rail has pressure and that the injectors are operating. I'm not familiar with the EFI version of that motor, but there may be a schrader valve on the fuel rail where you can check pressure. Someone more familiar with that motor than me can tell you for sure, or the service manual will have that info. For the injectors themselves, you can get a mechanics stethoscope on Amazon for cheap, it will have a metal rod that you can place on things to listen. If you place it on the injectors you can hear them ticking if they're working. Right now you're just guessing at things. I think you'll have a much easier time if you first figure out what isn't working, then figure out why, instead of taking guesses. Maybe someone here is familiar enough with that motor that they can point out a common failure that you can check first, but otherwise this is how I would do it. Good luck and let us know what happens.

 

[ahicks]

When you first turn the key on while it's "on break/not running or starting" do you hear the fuel pump running for a couple of seconds, then shutting off?

Filters (high pressure and low pressure) have been changed?

Does the motor seem hot?

 

[Michawilden]

Thanks for the replies.
I thought I had typed everything but I haven't. Before all this we did some testing. ( My dad dit, it is his motor) squizing the primer bulb after it dies. Checking for water in the sediment bowl, checking for fuel coming out of the connector. We changed out the fuel filter in the boat.

The problem is that my father isn't that mechanically inclined and the problem only arrises sporadically. So the times it does occur, I am not there.
The reason I installed the switch is so that he can do a check himself.

Since it runs well I don't expect over heating problems or problems with the fuel supply. It doesn't start when it already cooled for half an hour.

I have not changed the high and low pressure fuel filers. I will do that.

I will see if there is a bleed valve on the fuel rail. And check for pressure in a 'no-start' situation. And I will check for a fuel pump running when I turn the ignition switch

 

[Michawilden]

Still no anwser here. The motor doesn't die on us anymore. I do not hear a fuel pump running when I turn the key on btw