Yamaha 50 horse 4-stroke will not start

Good morning,<br /><br />I've got a problem with my Yamaha engine and I'm hoping someone on the board can give me some suggestions. Here's my story:<br /><br />I've got a 2003 Polarcraft 165sc with a 2003 50hp Yamaha 4-stroke. I bought the boat brand new in Oct, 2002. Late this summer, I took a trip to Lake Champlain to try and pick up some monster smallmouth. Unfortunately we did not do as well as we would have hoped. However, there were times when the water was quite choppy. The first day we were there, the swells were probably about 3 to 4 feet. I've only got a 16 1/2 foot boat so you can imagine how much fun that ride was. It was quite a bumpy week on the water and I am thinking that it may have had something to do with my current problem.<br /><br />The first time I took the boat out when I got home, I was having problems starting the engine. It would turn over just fine, but for some reason it would not run. Once I did get it running, the instrument panel was going nuts. It looked like I had some sort of electrical problem, so I assumed that was why my engine was having trouble starting. I took the boat out a few times after that. Sometimes it would start right away, other times it would be a huge pain in the *** before finally starting. <br /><br />The last time I took the boat out it was completely dead. I cannot get the motor to turnover whatsoever. I checked the fuses and they all look fine. I checked the ground wires that I know of to see if one of them was loose, but they look OK too. I need to fog my engine so I tried to pull start the engine........again, no luck. I'm thinking that there is some connection between my really rocky ride on Champlain, my instrument panel going nutty, and now my completely dead engine. <br /><br />Do you think that the problem is electrical? The engine is basically new and I never, ever had a problem with starting it before I went to Champlain. If the issue isn't electrical, what could it be? I can't imagine that the starter is dead. If it were, I would still be able to pull start it, right? Any help or suggestions would be greatly appreciated. <br /><br />Also, I've toyed with the idea of not fogging the engine (because I can't start it) and just putting it away for the winter. I could take it to a marine shop in the spring. I'm assuming this probably isn't a good idea, but is this something I could get away with for one winter? How vitally important is it to fog the engine before storing it? Thanks for the help guys.

Re: Yamaha 50 horse 4-stroke will not start

try another battery and use jumper cables to the same connections as the current cables. i have also been noticing bendix sprag problems on mid range four strokes. havent put my finger on the reason yet, but it has made for some hard starting. be sure to use no throttle if yours is a model with an electric choke.

Re: Yamaha 50 horse 4-stroke will not start

Thanks for the response. I'll give that a shot and see what I come up with.

Re: Yamaha 50 horse 4-stroke will not start

hello<br />also check your ign switch if its not a stock yamaha switch and gauge package. most the pre-rig polars use aftermarket switches and gauges that are sub standard in my opinion. did you try to rotate the flywheel by hand?<br /> and describe the no start better. was cranking speed normal and no start or was cranking speed slow?

Re: Yamaha 50 horse 4-stroke will not start

rodbolt,<br /><br />i did try to pull start it but i had no luck. i am getting nothing when i try to use the electric start. there is nothing happening, no cranking at all. <br /><br />it's funny you mention that the pre-rig polar craft switches are garbage. my gas gauge needs to be replaced as well. it only worked for the first year and then it was dead. <br /><br />any additional advice i could get on my starting problem would be greatly appreciated. thanks.

Re: Yamaha 50 horse 4-stroke will not start

Just a couple of thoughts which may help diagnose the problem(s). <br />Does your boat have a master electrical cut off switch? <br />Is anything else affected? <br />Which model 50hp Yam is it? <br />Please give as much info as possible so rodbolt or the other experts can help...

Re: Yamaha 50 horse 4-stroke will not start

when you have the extra battery connected locate the started relay and disconnect the brown wire. jump this wire to the positive battery connection.

Re: Yamaha 50 horse 4-stroke will not start

Triton II<br /><br />I do not believe my boat has a master electrical cut off switch.<br /><br />There are no other electrical problems on the boat.<br /><br />It's a 2003 50hp 4-stroke. <br /><br />The puzzling part of my problem is that I can't even get it started manually. It came with a cheap rope to wrap around the fly wheel in case an emergency start is needed. I can't even get it to cough when I try to pull start it.<br /><br />Also, I think it's noteworthy that this was a gradual problem. At first it just took a little time to start. It was turning over fine, just had a hard time starting......and it wasn't every time I tried to start it. The last time I took it out, it was DEAD.....absolutely dead.

Re: Yamaha 50 horse 4-stroke will not start

pull the main harness plug and retry my suggestions as well as pull starting.

Re: Yamaha 50 horse 4-stroke will not start

BenC, forgive me for my ignorance. Where might I find the main harness plug? What do you think the root of my problem is? Thanks for the suggestions.

Re: Yamaha 50 horse 4-stroke will not start

shurkis,<br />I have an older 50x4 stroke mariner which is supposed to be made by yamaha. The wiring may be similar. To make a long story short...When I first bought the motor there were times it had no electrical juice and wouldn't start. After lots of grief I traced the problem to the main harness connector under the cowl. The male pins are hollow and were too small in diameter to make contact all the time. I spread the pins and the problem went away. On my motor the connector is round and approx 5" long. It's mounted on the back of the block on the right side as you face the engine. My last try with the Zippyimage site wouldn't download here but I'll try this one.<br /><br />Bill<br /><br /> <br /><br />

Re: Yamaha 50 horse 4-stroke will not start

the main harness plug is under then engine cowl near the front of the engine. its the largest black plug you will see. im still trying to nail down where the problem lies. the boat or the engine. disconnecting the plug and jumping the extra battery while at the same time using the starter solenoid brown wire to crank will help with that. if your engine styarts while you do this simply plug the main harness together again with the ignition key off.

Re: Yamaha 50 horse 4-stroke will not start

BenC, the boat is actually about 40 minutes away from where I live so I haven't had a chance to try your suggestions. I'm going to give it a try this weekend and come back to post my results. Thank you all for your insight. I appreciate your help.

Re: Yamaha 50 horse 4-stroke will not start

First of all your dealer should dealing with this because the boat is new. Secondly, I had a similar problew with a Yamaha last year. It is most likely in the wiring harness between the motor and control cable. When that wire is streched or stressed it has a tendency to develope an intermitent short.