1987 Yamaha 200 no power

[MarkP]

Hello, I'm hoping someone can give me some insight. I have twin 1987 Yamaha 200 engines with 1100 hours on them. One runs fine, the other one will start and I can rev it in neutral but it will not idle and I cannot run it under a load. if I try to power up, the engine stalls. Here's what I've done so far, I've swapped carbs, CDI unit and stators from the good engine to the bad. No change. I've installed new fuel pumps and replaced all fuel lines. Compression is good and the timing advances properly. I've also checked and I have spark to all cylinders. Any ideas on what the problem could be?

Thanks
Mark

[CatCam]

Mark -

1. Not being too familiar with a two motor set up, is there two separate fuel tanks or just one? If there are two, try switching fuel lines....or run it from a small 6 gal tank.

2. If you can keep the one motor running long enough, try disconnecting the 10 pin connector at the motor, this will tell us if it is a problem with the remote control unit for the motor.

reply back and tell us if this revealed anything.....

CatCam

[MarkP]

there is one gas tank and 2 lines, one to each engine. I tried switching the gas lines early on and still had the same problem. That's when I started switching parts.
I switched all the secondary ignition coils today and it seemed to run better. Took the boat out and got it to run for longer. I decided it could not have been the coils since the good engine was still running fine with the coils from the bad engine.
I then came back and decided to bypass the fuel tank and lines completely, attaching a secondary gas tank directly into the fuel filter. Bad engine ran fine! It looks like I had stuff plugging the engine side of the fuel coupler. I switched fuel lines early on but it never occured to me that the engine side of the fuel coupler could be plugged! It looks like something melted the fuel side coupler and that gummed up the engine side of the coupler. I was able to get quite a bit of junk out of the couple. Ran out of daylight so I will test my bypass tomorrow. Thanks

[jb123]

do yourself a favor and remove both quick disconnects and run hoses directly to motor filters, ridding of the prob you had and an airleak possibility.

[CatCam]

Mark -
Great news that this sounds like a simple fuel problem. I'd still change out all of your fuel lines with new ones. Maybe some of the new Ethanol gas has attacked you fuel line??????

Post again and tell us the final outcome..


Merry Christmas....

CatCam

[DwayneD]

Eureka!!!! I Got It

Hay Mark, i was plagued with a simular problem, Motor would run at idle til i put a load on it and it would cut off. The problem lay with the so called VST filter. On the side of your motor you have a Aluminium box,this is part of your fuel management sys. inside this box is simular to your everyday toilet resevoir, you have a float and metering valve, fuel fills the box up, the float cuts the fuel off at a certain level until you demand power/more fuel. On the bottom of your metering valve is a removable plastice filter with a fine mesh screen, This screen is prob clogged, mine was. I removed it and Washed it in hot soapy water, dried and reinstalled it, guess what? got my hole shot back and she's running fine now. good luck.