1995 40 hp runs wide open wont idle down or shut of at ing switch

[BOZ304]

OK HERES MY STORY I SEIZED UP MY 1995 40 HP EVINRUDE LAST FRIDAY (rod bearing disentagrated ) it was running better than ever too at this time ??? i almost leaned over and mentioned this to the passenger then down in the water i went . so i found a used power head and replaced mine got everything switch over today and much to my amazement it all fit with no extra parts left over i was quite proud and went it fired up i was all smiles i check the VRO pump and visually ensured it was pumping (i can see the oil flowing in the clear tube leading to the pump) my problem is when i throtle up wide open it wont back off runs wide open and the ingnition wont shut it off either i have to close of the top carb intake with my hand the lower carb wont make no diffrence then i will restart and motor idles fine again till i open it up then same scenario i cant git it to shut down .... now i fish a small local lake and if this thing act up in a cove i want to fish id end up on the bank in some ones camper>>> any help or direction will be appreciated.... wondering if this is what cooked my first motor like i said it was running better than ever

 

[BOZ304]

Re: 1995 40 hp runs wide open wont idle down or shut of at ing switch

Also the cable and linkage are free this is not holding the throtle open

 

[hidef]

Re: 1995 40 hp runs wide open wont idle down or shut of at ing switch

Recheck all of linkages and make sure the throttle is closing correctly and all the hoses are attached correctly also. Next make sure the yellow and black wire leading into the power pack is good. That is the kill wire. Touching it to ground will kill the ignition. Next I would clean the carbs and all the gaskets are good. I suspect you had one carb running lean and that is what caused the bearing to go.

 

[BOZ304]

Re: 1995 40 hp runs wide open wont idle down or shut of at ing switch

i have checked carb linkage and suspected a lean mix also on the first powerhead the key switch will work when motor is at slow idle but once i give a little throtle to it she stays wide open and then the key switch wont shut it off either nor will the dead man switch as =far as the lean mix is the only solution to that is premix as far as i can tell the pump is drawing oil into be mixed at pump

 

[hidef]

Re: 1995 40 hp runs wide open wont idle down or shut of at ing switch

I do not believe you have a VRO problem but a plugged carb. A dirty carb will cause the engine to run lean and it will cause a bearing failure. You need to check all of your wiring The yellow black wire to the power pack is the kill circuit make sure you continuity from the switch to the engine. When the switch is off that wire should show 0 ohms with one lead on the wire and the other grounded on the engine. If it doesn't that is your issue.

If it was my engine I would get two carb kits and clean the carbs and check the wiring for breaks. If you do not have a repair manual get the BRP/OMC repair manual for your engine it will make troubleshooting easier.

 

[Faztbullet]

Re: 1995 40 hp runs wide open wont idle down or shut of at ing switch

Your not running it WOT on a hose are you??? If so it is "4 stroking ' and that will break piston skirts and send rods thru block sides.

 

[BOZ304]

Re: 1995 40 hp runs wide open wont idle down or shut of at ing switch

WOT---- WIDE OPEN THROTLE ??? i am on a hose and only testing after power head replacement this motor starts fine idles fine then i give it throtle and it goes wide open and will not back off and at this point it wont shut down with ingition switch either i have to block top carb off with hand to get motor to die the lower carb makes no diffrence if i "choke it out with hand" ...at slow idle it will shut off and restart with switch many times but when it goes wide open theres no kill switch on the key

 

[hidef]

Re: 1995 40 hp runs wide open wont idle down or shut of at ing switch

So the switch will shut it off at idle the kill circuit is fine. What do the plugs look like after running the engine? I still believe you have a dirty carb and if you are using your original carbs they need to be cleaned. Also you should not rev the engine while on the hose as it can run away and not shut off unless you choke it. Which sounds like you have to do.

 

[JB]

Re: 1995 40 hp runs wide open wont idle down or shut of at ing switch

You are going to destroy that powerhead, too, if you rev to WOT with no load on the prop, BOZ. You are putting it into thermal runaway, as hidef points out.

NEVER rev a 2 stroke over about 1500rpm with no load on it. Thermal runaway is a probability and explosion possible.

 

[BOZ304]

Re: 1995 40 hp runs wide open wont idle down or shut of at ing switch

ok now let me get this straight correct me if im wrong but you are saying that this runaway is so called normal on a hose if so im thinking im ok to go. and this runaway is caused by the hose, thermal runaway as you say i do respect everyones oppinion and never knew this but i have a hard time understanding way it still wont back down or shut off but if you say its because its on a hose i shouldnt need carb cleaned ect just live closer to the lake so i can check with a load keep the advice comiming Hidef and Jb

 

[BOZ304]

Re: 1995 40 hp runs wide open wont idle down or shut of at ing switch

ok so i search thermal runaway on this site i can see a pattern with these evinrude 40 48 and 50s but others do it also is there a easy way to de carb the cylinders Mechanic in a can type thing i cant see why though that when the throtle is back off it dont remove the fuel to prevent the runaway this motor idles nicely until i give it a little then LOOK OUT so please keep givin me the info or terminology and ill look it up thanks again you guys

 

[hidef]

Re: 1995 40 hp runs wide open wont idle down or shut of at ing switch

Thermal runaway can be caused by a heavily carboned engine however it can also be caused by an engine having no back pressure. You could put the motor in a garbage can and fill it with water and see how it runs. I prefer the garbage can method myself because it is quieter and there is less chance of a runaway. You still haven't answered the question are you using the carbs from the original powerhead that self destructed? If you are you should thoroughly clean them because the previous power head had a lean condition most likely caused by a dirty carbs. If you don't want to clean the carbs fine but if I was you I would be concerned that blocking one carb has no impact on the engine running while blocking the other one does.

 

[Cap'n Chaos]

Re: 1995 40 hp runs wide open wont idle down or shut of at ing switch

To decarb you can use a product called Seafoam... you mix it in with your pre-mix... it smokes like crazy but it works.

I don't know a thing about your motor so I'll sit back and learn from here on out.

 

[BOZ304]

Re: 1995 40 hp runs wide open wont idle down or shut of at ing switch

Cap'n i just got a can of that thanks though .... and Hidef i didnt mean to skirt the question of the old carbs yes they are my original carbs ... now when you talk lean are you talking lean air/fuel or lean fuel /oil and if this helps any the lower cylinder is where the failure happened on the original power head (rod bearing failure) now when this thermal runaway happens i can only ''HAND CHOKE " the upper carb the lower one makes no difference in the runaway WOT condition and this is the carb that feeds the cylinder that failed....also i notices as i disassembled old block the upper (good) rod was a Coppertone color the lower rod is kinda dull aluminish color ...from the mechanical breakdown i am assuming the from small parts being hammered and ground to nothing ..... so please explain if im trying to understand lean air/fuelmix or lean fuel/oil mix i know the oil and fuel kinda mean the same thing but not really

 

[hidef]

Re: 1995 40 hp runs wide open wont idle down or shut of at ing switch

The dirty carb is going to give you a lean fuel/air mixture but remember the fuel mixture also carries the lubricating oil to the bearings. No fuel means no oil when you are dealing with a 2 stroke. Putting you hand over either carb should affect the operation of the engine. I would as stated get two carb kits and clean both carbs. You need to figure out caused the original failure which I think you already have. The bottom carb has been running lean and you burnt up a crank bearing causing the failure.

 

[BOZ304]

Re: 1995 40 hp runs wide open wont idle down or shut of at ing switch

Ok got my kits will pick them up befor i got to work at 4 pm I ALREADY HAVE DISASEMBLED the suspected bad carb there is no deposites in bowl and all passages are clear i blown carb cleaner and ran a melted bread tie wire thru all i was hopeing to find some type of evidence that this was a the problem however my UNTRAINED eye is not seeing anything obvious as i shine a light in the intake manifold the reeds all appear fine and seated the high speed orfice in the lower part of the bowl does not appear to have any type of adjustment just a fixed orrfice is this correct and this is where the diffrence in horspower ratings are made ??? (IM PUTTING THE KIT MY MOTOR CALLS FOR BACK IN ) just wondering if there is anything "top secret'' i need to be looking for also i got some seefoam yesterday but will wait to put it fuel until i reassemble everything

 

[BOZ304]

Re: 1995 40 hp runs wide open wont idle down or shut of at ing switch

ok i will create a new thread soon to make a statement if the person you are asking for advice is willing to give it you should be willing to listen to it and at least try it .......... If they tell you not to run it on a hose /muffs dont after 20 hours at least fighting this theremal runaway with no avail i put the motor in a tank it will not runaway for nothing now problem solved thanks everyone for your advice Im a little hard headed but the new powerhead is still in 1 peice...... ive installed carb kits even went and changed reed valves sea foam i am pretty good at taking this one apart though.......... thanks again