90 yamaha 250 sat for 3 years. now will die after start.

letsbarbq

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I've just took out all six carbs and cleaned them. they were very dirty. I just changed the water pump. I just change the lower unit oil. I have not changed the spark plugs or the spak plug wires. on water hose. I prime bulb is hard after several pumps. I have water separator filter. starts easy. but once fired it will hesitate, rpm go up and down, then die. Same if I give it some gas and start it, it will slowly go up and down (rpm) and then die. What is the cause? It got real dark out so I was not able to play with it more cause of the neighborhood. so I was force to quit. I did check the prime bulb and it was still stiff. I did one time put it in forward and it died almost immediately. but did not try it again. I know I should have. --- could it be water in gas tank? Or I did not clean carburetors good enough? spark plugs? will spraying a can of decarb into the carbs and running it fix the problem? but I am thinking.......its not even working smoothly enough for me to spray it in? can I do this? Any help or anyone with a similar problem like this will be appreciated.<br /><br />anxious to start tomorrow after work.
 

Solittle

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Re: 90 yamaha 250 sat for 3 years. now will die after start.

I ain't the expert by far in this but I suspect that those that are will tell you that there is a big difference between cleaning your carbs and a complete dissambly, clean and rebuild with a carb kit. I would also remove every - as in every - drop of old fuel in the tank, all lines, filter and fuel pump.<br /><br />There are a slug of posts here on the same problem. Also check the Search function.
 

iRich

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Re: 90 yamaha 250 sat for 3 years. now will die after start.

Hi, Do you have the vent open on the gas tank? <br /><br />Rich
 

letsbarbq

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Re: 90 yamaha 250 sat for 3 years. now will die after start.

its 10 pm right now. I am so tempted to rev up the engine to see what the heck is going on. but I live in a freakin quiet neighborhood so I must control myself. I took apart the carbs and cleaned it all. except the high jet in the bowl that had the float. ---stupid me, I should have taken that out and cleaned it. --- could this be the problem? I am gonna try it on a 6 gallon tomorrow and see if it makes a difference. if it doesn't I think I might have ignored the wrong thing... HIGH JETS........this is my first time doing carbs. what is in a rebuild kit for a carburators?
 

Hooty

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Re: 90 yamaha 250 sat for 3 years. now will die after start.

I just found your second post. That's REAL confusing. It's a lot easier if you keep it all together Are you trying to run the old fuel? When did you check compression, before or after starting.<br /><br />c/6<br /><br />Hooty
 

letsbarbq

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Re: 90 yamaha 250 sat for 3 years. now will die after start.

sorry for the mix up, I'm not thinking straight. yes its the same fuel in the tank. I ran a compression testbefore I have did all of this or any of the maintenance to the boat. is 95 psi in all six cylinders low?
 

Sand Bass

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Jul 17, 2002
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Re: 90 yamaha 250 sat for 3 years. now will die after start.

Hey BBQ, I grew up in Orange TX. I would get rid of all the old gas. Install carb kits. I use a small piece of wire and carb cleaner to make sure all jets are clean. If it makes you feel better I have similar compression on my 225 Evinrude and the motor runs great. Good luck with new motor.
 

Bear

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Re: 90 yamaha 250 sat for 3 years. now will die after start.

Try with fresh fuel first. Drain the carbs. Pump the primer bulb and drain them again. <br />If there is no improvement, clean the carbs again. Make sure there is no air leaks around the carb gaskets.<br /><br />I'd save the carb kit $$ for later. <br /><br />Good luck!
 

letsbarbq

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Re: 90 yamaha 250 sat for 3 years. now will die after start.

irich, hooty, sandbass and bear.<br /><br />I could not sleep well last night. I just got this engine Sunday......so I am little anxious to get it running. I am gonna get out my 6 gallon test tank and try it. then i'll let you know what goes from there. If all else fails, I will take out those carbs again and soak and clean them again. This time, I will not forget to take out the main jet, this is the jet that is in the bowel with the float. will me not cleaning this but the whole rest, still affect the performance? I think you are saying OFCOURSE. remember, i'm a first time carb cleaner.
 

letsbarbq

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Re: 90 yamaha 250 sat for 3 years. now will die after start.

thanks bear very educational. thanks a bunch. <br /><br />I just ran the motor on a 6 gallon test tank. it ran better, but did not die. but once I put it in gear, at the initial rpms...from 7-mid teens, it will hesitate to die. but if i quickly rev it higher, it will stay? idle is fine, but it will spit every once awhile. ??? do I need to go back and clean more? or will a decarb spray help? what about the fuel pump. I read somewhere here that the fuel pump needs to be rebuilt as well after it sits up for a long time. is this true?
 

rbu

Seaman
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Jan 17, 2002
Messages
66
Re: 90 yamaha 250 sat for 3 years. now will die after start.

I'm trying to make sense of everything you have done so forgive me if I have missed something.<br /><br />First, you say your compression is 95 in all 6 cylinders? That's low. I would re-check. Could be your gauge.<br /><br />Did you get around to changing the plugs yet?<br /><br />You mentioned a de-carb spray, that's for removing carbon build up in the cylinders. If you are going to do that, then keep your old plugs in and replace them when you are finished with the process.<br /><br />As for the fuel pumps, if they are original, I would replace them, forget the rebuild. They are only about $25 each. The screws in the older fuel pumps have a tendency to rust. I don't believe that Yamaha was using all stainless hardware in them back then.<br /><br />As for getting this all together, I would stick with the 6 gallon tank. De-carb the engine, change the plugs and fuel pumps. Fire her up. If all is well, go to the main tank. If there is old gas in there you're going to have to get rid of it. And let's just hope that the compression is OK.
 

letsbarbq

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Re: 90 yamaha 250 sat for 3 years. now will die after start.

Just got in an hour ago and finished a productive day. ran it off gas tank in 6 gallon can and had 5 - 5 gallon tanks backup. I removed the carbs again and cleaned it again. this time I removed the main jets and cleaned them good. put everything back and the motor ran fine. but when I was out driving and after I anchor and pulled it up an hour or two later, the engine would spit alittle and sometimes die when in low rpms. Is this cause I need to decarb the motor and then replace the spark plugs? No, i have not replace any of this yet. But I will tomorrow. now I got a prop. problem. I"ll post it on a fresh thread. thanks for all the help.
 
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