25hp four stroke won't start

[h2omelon]

I have a 1998 Yamaha 25hp four stroke motor that won't start. It's been running fine but a couple days ago I cranked it and it started, ran a few seconds and stopped. I got it to start and run briefly two more times. Now it won't start. I noticed that the priming bulb would not get get tight so I replaced the tank and fuel hose assembly. Still no luck. Fuel filter is good. Could it be the fuel pump?

Any help would be appreciated.

 

[TheOrganicMechanic]

Re: 25hp four stroke won't start

Probably not the fuel pump as you bypass the pump initially by squeezing your primer bulb. Check the plugs first - if they're wet with fuel this often means the ignition system isn't working, check for spark. Black/ fouled - replace or try to clean them. This is the best place to start. If the plugs look good and you have spark its likely you have water or trash in the carburetor preventing fuel from entering the cylinders.

Ben
Browning Marine Service - FL
browningmarine@yahoo.com

 

[h2omelon]

Re: 25hp four stroke won't start

Thank you for the response. There is fuel on the plugs but I'm not getting any spark on one of the plugs and the other one sparks intermittently. Could the ignition coil be bad?

 

[TheOrganicMechanic]

Re: 25hp four stroke won't start

Could be the igntiton coil, that would be the easiest fix. Could also be any of the ignition components - coil, stator, trigger, cdi box, or even the kill circuit. If you have a peak reading voltage meter you can test the system outputs for proper voltage(let me know and I will see if I can find the specs for you), otherwise I would find a local mechanic and ask them to do a quick ignition system diagnostic (a good mechanic should only charge an hour or so) and then you can replace the faulty parts yourself.

Ben
BROWNING MARINE SERVICE - FL
browningmarine@yahoo.com

 

[Knightgang]

Re: 25hp four stroke won't start

Not familiar with that engine, but I know many have idividual coil packs, usually one per cylinder. I would say that if one is not sparking and another is intermitten, then it is not the coils, but like stated, bayme the cdi or the stator. But I would rule out coils as multiples do not usually go bad at the same time...

Good luck...