2001 Yamaha 50hp tlrz 2 stroke with prime start system starts and dies

[tdave]

Well I got side tracked a little bit working on some hot rods and got back to my boat motor today. Long story short I believe I solved the issue of not running longer than 30 seconds. After doing a bunch of voltage tests etc. I took off the carbs and discovered the center carb was missing the double O-ring on the back. New one is ordered and hopefully will solve the mystery. Will report back after new O ring installed.

 

[99yam40]

Well I got side tracked a little bit working on some hot rods and got back to my boat motor today. Long story short I believe I solved the issue of not running longer than 30 seconds. After doing a bunch of voltage tests etc. I took off the carbs and discovered the center carb was missing the double O-ring on the back. New one is ordered and hopefully will solve the mystery. Will report back after new O ring installed.

who replaced that center carb?
you or someone else?

hope it is that simple of a problem

 

[tdave]

A friend of mine did the replacement of the center carb. He knows hot rods but boat motors not so much. I do not know if the new center carb that was purchased came with that O ring or not but I know it is missing now. I too hope that is the issue.

 

[99yam40]

should have used the old one when he put the new carb on, old is better than none

 

[tdave]

Got around to installing the new O ring between rain showers. Made no difference and was not the problem. It gets gas, ball stays hard/firm, have spark on all 3 plugs. It acts as if someone turns the key off when it dies, no coughing or sputtering. Will start right back up immediately and run for 30 seconds and die. Seems like a kill switch is turned on. Will do some more head scratching and figure out what to check next.

 

[tdave]

Did a little more checking today and decided to check the oil sensor and it failed the test. Also discovered the plastic clip on the oil linkage to the bottom carb was broken. Will get replacement parts and go from there.

 

[tdave]

Unable to find information on adjusting the oil sensor linkage for this 2001 Yamaha 50HP TLRZ 2 stroke in my repair manual. Help appreciated.

 

[99yam40]

I have no idea what linkage its tided to an oil sensor. pics may help

 

[tdave]

Linkage is located below oil reservoir and is connected to bottom carb and throttle linkage. Part of the autolube system. Boat and motor are kept some 30 miles from home (present location) so pictures are not currently available. will get back out there sometime this week to install new oil sensor wiring.

 

[99yam40]

only oil sensor on that motor I know about is the float switch in oil tank, and no linkage is hooked to it.
the oil pump does have a link to the throttle so it can change the output of the pumps as throttle goes open for higher RPM

 

[tdave]

The oil pump linkage is what I was referring to that will need to be adjusted after new plastic connector is installed. I believe chapter 4 in my repair manual may cover adjustment info I need.

 

[tdave]

Well 1 step forward and 2 back today. Got the parts I needed and first off noticed the old oil sensor wiring had a modification somebody had done. The harness out of the sensor consists of 4 wires, a black (ground) a pink, a green and a green with red stripe. At the plug end of the harness someone had joined the pink and the green wire leaving about 2 inches of capped off green wire that attaches to nothing. I replaced the wire harness with the new one and put everything back together, topped off the oil and started the engine. Immediately got the sound of a horn from the shifting lever. The engine ran for about 10 seconds and died. I repeated the same exercise about 3 times. I suspect the original wire harness with the pink and green wire together was a bypass for the horn I am now hearing. Not sure what my next step should be. Engine is definitely getting oil but only runs for 10 seconds now when it used to run for about 30.

 

[99yam40]

low oil or over heat will set the buzzer, but neither will shut down the motor

 

[tdave]

Got to look a little deeper into my engine today. Disconnected the oil sensor plug on oil tank side. Buzzer went away. Pulled all 3 carbs and went through checking and cleaning, no issues noted. Did the link and sync checking specs as per repair manual. I accidentally got the engine to run correctly by disconnecting the linkage at the CDI and advancing the timing. When I hook up the linkage with everything set to specs the engine runs for 30 seconds and dies. Again when I disconnect the CDI linkage and manually advance the timing several degrees past the 7 degrees mark on the CDI box the engine runs flawlessly. Definitely a timing issue.

 

[99yam40]

I had to replace my CDI due to the idle timing retarded 14 Deg when set to the marks on CDI.
others had jacked with all the carb linkages just to get it to idle, WOT was as problem.
and it did not help that they had drilled out the main jets too.
took me a long time to finally get the motor to run well

 

[tdave]

I guess I have to bite the bullet and buy a new CDI unit 117-63D-04 which replaces 63D-85540-02-00 . Here is a picture of where the pointer on the CDI Box has to be for the motor to run.

I know of no way to make that much of adjustment. Am I correct in thinking the CDI Box needs to be replaced?

 

[99yam40]

if timing is not close to correct with the wiper pointed at the marks, then I would say it needs replacing.
what does the timing light show the timing at when wiper set to where the motor will run?

 

[tdave]

I am not where my boat is so cannot verify what the timing was when motor was running properly but if you look at the photo of the CDI box and you can see the pointer is somewhat between the 7 degree hashmark and the 25 degree hashmark. A rough estimate would be about 12 degrees.

 

[99yam40]

idle timing is After TDC, ( retarded timing)
WOT timing is Before TDC.(advanced timing)
guessing at what the timing is actually doing by looking at the none functional wiper does not help at all

 

[tdave]

I will get the new CDI Box on Tuesday and check all the settings again and also check the timing setting needed to run the motor before I install the new CDI Box. Should know if the problem is fixed sometime on Wednesday. Thanks, Tom