1992 115 HP Yamaha v4 2-stroke outboard: Cold Starting Issues

[lotwsolar]

Hi There.

Long time listener, first time caller.

A friend of mine has a 1992 115 HP Yamaha V4 (2-cycle) Outboard that has cold starting issues. Here are the quick details:

Turns over OK. Electrical appears OK. Spark on all cylinders. Just won't fire. The problem is intermittent.

What I am noticing is that there appears to be a large fuel slick behind the boat after even moderate amounts of cranking. This has been an ongoing intermittent problem for my buddy.Sometimes he has no issues cold starting and other times it seems to be impossible to get it to fire. He has had the CDI unit changed as it was determined last year that this may have been part of the problem. I personally think there is a underlying problem we just aren't seeing.

When the motor does start and run it runs flawlessly. No misfires or skips. This is a 2-cycle that is NOT oil injected.

I can tell you anything else you need to know to perhaps help diagnose. I'm just wondering if anyone else out there has seen this problem or something like it.

Thanks!!

 

[jeffersondodson561]

Re: 1992 115 HP Yamaha v4 2-stroke outboard: Cold Starting Issues

Might want to pull the airbox off and look at the choke plate shutters. They may be not opening all the way after choke is released. Possible torn fuel pump diaphram could be leaking fuel into crank case. Might want to put some spray lubricant on the choke solenoid stopper as well.

 

[SparkieBoat]

Re: 1992 115 HP Yamaha v4 2-stroke outboard: Cold Starting Issues

sounds like a choke issue to me also.

 

[lotwsolar]

Re: 1992 115 HP Yamaha v4 2-stroke outboard: Cold Starting Issues

Might want to pull the airbox off and look at the choke plate shutters. They may be not opening all the way after choke is released. Possible torn fuel pump diaphram could be leaking fuel into crank case. Might want to put some spray lubricant on the choke solenoid stopper as well.

Thanks. We pulled the airbox off and checked out the choke plate shutters. They do appear to be opening and closing completely. There doesn't seem to be anything sticky in the choke mechanism.

Is there any way to check for fuel leakage into the crack case due to pump diaphragm rupture? Based on my observations I believe the fuel slick behind the boat is more do to operator flooding the engine (IE. pump primer ball, turn over, doesn't start. lift fast idle level, hit choke button, turn over, doesn't start. rinse and repeat but by this time the plugs are completely fouled.)

Thanks for the input.

 

[SparkieBoat]

Re: 1992 115 HP Yamaha v4 2-stroke outboard: Cold Starting Issues

take your fuel pump apart and look at the diaphragm. are ALL the choke plates in sync??? also you may need to clean out your carbs, could be clogged idle passages. new plugs also.

 

[99yam40]

Re: 1992 115 HP Yamaha v4 2-stroke outboard: Cold Starting Issues

Seems like I have read that you can unbolt the pump from the motor. leaving the fuel lines attached.
And then pump the primer bulb up tight while watching to see if any fuel comes out of crank case pulse port of the pump.
Also if there are leaks from around the edges between plates, then you may need to install some bolts/screws and nuts to keep the plates tight together while testing.

from what I understand about motors with electric choke, you need to lift the fast idle lever some and then hit the choke while turning over to give it enough air for it to fire up properly otherwise it will flood