major scary issue. ski isnt even safe to take to water

[dkello1]

So i oredered a "rebuilt" carb off of this guy waterworxx from ebay for my 951 01 rx.... first off, kids a crook. the return nipple on the mag side was broken off. then i put a replacement from my old carbs on the rebuilt carb...pull the fuel filter... surprise.... has crap in it. well i clean both filters and keep on moving. adjust my low speed screws, install carb and set idle to 3000 out of water just like manual recommends... ok success.... it smokes like a mosquito fogger but at this point im just happy to hear it run.


Well today i get it out in the driveway for a little flushing and prelim-testing just to check my water worthiness.....its running slightly rough, has a little bog in it under initial load from the throttle, again something i was concerned about but didnt think it would affect me all that bad.

after about a minute of warming it up i get the hose ready and then BAM.... as i am popping the throttle slightly listening to the bog issue the motor goes f***ing berzerk and revs up to 5000 and stays there, in a panic, i hit the stop button.. doesnt turn off... pull my dess key... STILL DOESNT SHUT OFF.... pull the plug wires off of the plugs while its running...and ill be damned it still doesnt shut off.... i pop the throttle real quick and then it finally dies ironically enough...


pissed off and in a rage i give the motor another crank and starts right up... idles, revs and does the normal things it should... stop button works, start it again, removed the dess key... shuts off...



WHAT IS HAPPENING TO ME?!?!?!


i genuinely am concerned that this may cause my to kill myself out on the water if this thing decides to rev out of no where and out of controll.. and again it seems the only way to kill the engine when it does this is actually giving it more throttle and then backing off.... any ideas?



also pulled the plugs, pto side was clackish brownish and kinda wet but the mag side was chalked dry black.... what is my issue here? running lean on one cylinder?


when i did the carb re-install did i have to do anything different other than just connect all of my lines back up?


rawr!

 

[Bills86e]

Its an idle nut adjustment prob. Beside the fact Dan sold a used carb.
If the engine continued to run without the electrical system (i.e. the lanyard was removed), the fuel has to be getting ignited from somewhere. Likely you have some carbon deposits in the combustion chamber that are getting hot enough to ignite the fuel. Carbon deposits are very common in two stroke engines. In addition to rebuilding the carbs, I'd suggest decarboning the engine using your favorite method. You'll likely need to replace the plugs afterward, but you should do that annually anyway.

Ever hear the term "Glowplugging" the tip of the sparkplug gets red hot and ignites the fuel without electrical imput to the sparkplug.
This happens when the motor runs too lean of an air/fuel mixture. Too much air, not enough fuel. Fuel keeps the combustion temps within a certain safe range. Take away the fuel just a little bit and you have a glowplugging motor that revs to the moon ! Air leaks anywhere into the motor case will cause a lean condition.

Check to see if the throttle cable has slack in it when it is at rest. The most common problem of a runaway idle is that the last guy did not install the throttle cable with enough slack in it. But that only appluies to one that has had work done to the carbs or to the cables.
Sometimes richening the low speed adjusters will stop this runaway condition, unless the jets or filters inside the carbs are clogged up.

They run away because they are too lean for the amount of fuel being put into the motor. They get too mch air, and not enough fuel.951 engines will run away even without air leaks or lean condition. Check the archives for Bill's instructions on setting the idle on 951 engines. They will run away if the idle speed is set too high. If I recall, he warns that you must have slack in the throttle cable at the idle position, and to set the on-hose idle speed to 2800 rpm, 1400 or so in the water.

I just had this happen to a newly rebuilt 951. Idle speed was set to 3200 rpm, and it would runaway on the hose. Back idle off to 2800 rpm and it won't run away anymore on the hose.

Air leaks anywhere into the motor will cause a lean condition.
Tight cables cause a lean condition.
Clogged fuel systems and pet**** valves and carbs cause a lean condition.
L.S. Adjusters set too lean cause a lean condition at idle speeds.

Engines that shut off by themselves when riding along are often seizing the pistons from a lean condition, same as if you pulled the lanyard off. When the lean seize happens, it is often mistaken for an electrical issue.

 

[Chester]

I agree with everything Bill said. An additional thing to check is for a bent throttle plate
Also, next time it happens, just pull the choke out to flood the engine. Don't be concerned about it happening on the water, it won't. A lean engine runaway will not happen when there is a load on the engine (in the water) but it could seize the engine.

Chester

 

[flip6]

Had exactly The same problem with an xp 951.

Thought i was going mad when i pulled the spark plug caps and motor was still full noise.

If it happens agin hit the choke and that apparently kills the engine i was told.

The cause is running lean. I rebuilt my carbs and all was good.

 

[dkello1]

alright took some advice, and also called dan..even though i was as mad as i was....to his credit he did call to and talk me down out of my "raging" state of mind about the situatino. he explained to me the kind of boat they came out of and described some of the same fixes that you guys are... i took the advice, bit the bullet and pulled them back off....... which by the way sucks pulling off a carb set off of a rx haha. problem ended up being 2 fold.


accel pump was off an older model which had a MUCH smaller accel pump about 60% smaller. so i checked the accel pump off of the orig carbs, tested for air and leaks and then retro fitted it to the rebuilt carbs from dan.....



before fully installing i checked both squirters (official terms here guys lol) and the pto side was clogged like a mother. sprayed some carb cleaner in it and let it sit for a second and grabbed my air compressor and got all the crap out of it.....VIOLA! both jets squirt.


throttle cable WAS too tight, so sorry dan for blowing you up like that haha.

though it was not so tight as to keep the throttle cracked open hardly at all i can see that this was a spot of neglect in my install....


so hopefully this thread helps somone who has the same issue cause the runaway motor thing is a SCARY situation and an IN water runaway would be my wost fear as i bought these so that my family has something fun to do this summer.......


you guys are awesome and thanks for the advice

 

[Chester]

...an IN water runaway would be my wost fear as i bought these so that my family has something fun to do this summer.......


you guys are awesome and thanks for the advice

Not to worry, a lean runaway will NEVER happen in the water due to the load on the engine. The engine will just stall or hesitate when you accelerate.

Chester

 

[riverrat88]

Did you install new gaskets between the carbs and engine? Very important that ther are no nicks or defects in those gaskets or they will leak air and the engine will run like you describe. Next time use the choke to kill the engine.

 

[dkello1]

hey riverratt, just wanted to give credit where credit is due. i eneded up realizing that only half of each gasket was actually still on the motor. i tried the "make your own" gasket from autozone.... what a pointless endeavor. i have my new gaskets on order. I think this should fix my issues. thanks again!

 

[FlyNavy]

When this is finally solved, please tell Toyota. They need your help with run away engines.

 

[seadoosnipe]

Gaskets..?

hey riverratt, just wanted to give credit where credit is due. i eneded up realizing that only half of each gasket was actually still on the motor. i tried the "make your own" gasket from autozone.... what a pointless endeavor. i have my new gaskets on order. I think this should fix my issues. thanks again!

Why is it pointless?.... I"ve been making my own gaskets for many, many years. I personally think its pointless to pay someone else to make gaskets I can make myself.

I do not make impregnated gaskets, that are necessary for the exhaust manifold, tuned pipe at the loop or cylinder head gaskets. But, the simple gaskets like carbs, magneto, flame arrestor support, RAVE,..... I make them myself. They don't leak either. I've saved a butt load of money (I feel like that GEICO lizard...LOL).:cheers:

 

[dkello1]

Called toyota, they said they had no record of runaway engines in the mysterious black box that is in every sold toyota. sounds like a sham =)

and snipe, i liked my own gasket idea but it ended up looking like a 3 year olds coloring book. i didnt really stay in the lines if ya know what i mean lol....

ps, i actually work for GEICO, the lizard is a mysterious creature, even we dont know where he is from... but i kid you not im always on the lookout for that stack of money with the eye balls!!

 

[riverrat88]

hey riverratt, just wanted to give credit where credit is due. i eneded up realizing that only half of each gasket was actually still on the motor. i tried the "make your own" gasket from autozone.... what a pointless endeavor. i have my new gaskets on order. I think this should fix my issues. thanks again!

No problem, glad to help.