2002 50 HP Four Stroke problem

[billynjuls]

I recently purchased a boat that had a 2002 Mercury 50 HP 4-cyl 4-stroke EFI motor. I purchased it from an older gentlemen and it had been sitting for about 2 years. The cowling was always installed and the motor looks brand new. I doubt if it has 10 hours on it. It cranks strong with good spark, but will not start. When I choke it, the fuel enrichment valve (choke) does not click. It has two yellow w/black wires going to it. There is also 2 yellow w/black wires coming from under the flywheel. When I check for voltage a little ways after the ignition switch I have 12 volts for the choke wire (yellow w/black), but when I check it at the choke itself I have 0. I can't figure out where I am losing power at. The wires running down the bulkhead going into the engine are in a hardened shield so I doubt there is a broken wire in there. Should it be able to start without the choke working or is it that difficult on a 4-stroke EFI to start without it? Thanks for any help.

Billy

 

[ret1sgrja]

Re: 2002 50 HP Four Stroke problem

If this truely is a 4-stroke EFI, there is not a choke. The ecm controls fuel delivery. But if this motor has set for two years I would bet that the electric fuel pump is seized up. When you turn the key to the run position, you should hear the electric pump hum for about two seconds. If you do not hear anything you can check for voltage going to the pump when you key on. If you have voltage and it does not run, your last ditch effort before buying a new fuel pump would be to remove the pump from the vapor seperator and soak it in a 50/50 fuel stabilizer/ gas mix over night, after soaking apply voltage to the positive wire for a second at a time and see if you can get it to run again. If not then you will probably have to replace it.

Have a great day

 

[billynjuls]

Re: 2002 50 HP Four Stroke problem

Thanks for your reply. I guess I'm a little confused. When I go to NADA and put in my Serial # it shows it as a 50ELPT EFI. When I look at my wiring diagram it shows yellow w/black wire as choke. The back of the ignition switch also has a place for choke. There are two yellow w/black wires running to what looks like an elbow that connects on top of a metal piece that runs down the length of the carbs. Any ideas?

Billy

 

[ret1sgrja]

Re: 2002 50 HP Four Stroke problem

I am a little confused also. Forget the ignition switch, it is a generic switch that fits all. The motor is either EFI or it has carbs on it . You never gave the serial #. Look at it closely and determine what you have, they are really two different animals,with different systems, let me know and I will try to help.

Becky

 

[Dunaruna]

Re: 2002 50 HP Four Stroke problem

If it is an EFI -

Look at the back of the motor, there is a small fuse block with 5 fuses. The one in the middle is a spare. The one marked 'a' is for smartcraft, 'b' is fuel pump/idle air control/injectors, 'c' is main relay, 'd' is ignition coil.

A blown 'b', 'c' or 'd' will result in a no start situation.

'c' regularly blows when connecting the battery while acc is on. Check 'c'.

Could you please post a serial number.