Problem that needs Solving

Kendyl318

Kendyl318

Location
Sacramento
Hello, I am new to to this forum.
I have a 701 Yamaha Blaster and my issue is that after about 5-10 minutes of riding normally, the engine slowly starts to die on me. I just rebuilt the motor because of the same issue, come to find out that rebuilding the motor did not fix the issue. My thoughts are either to rebuild the carb, swap out the cdi or replace all electrical wires (including leading to ignition). I do not think ignition is cause of the issue because it starts and stops when I want it to and runs well. Overall, the blaster gradually/slowly starts to die on me while riding. Any suggestions or anyone has had the same issue?
Thanks
 
Kendyl318

Kendyl318

Location
Sacramento
augustaf said:
You might suspect the stator or cdi, the carbs are not that temperature sensitive.
Click to expand...
I don’t think it’s the star or due to my battery still remaining fully charged after every ride. I suspect the cdi as well as the temperature sensor on top of the head. Might be faulty and telling the engine to shut off due to a false over heating reading
 
augustaf

augustaf

Location
central florida
Be advised: the stator has 3 coils: a lightening coil (charges battery, never fails), a charge coil (charges the capacitors in the cdi) and a (smaller) pulser coil which let's the cdi know when to fire. Charge coils have been failing when hot, for me and others for four decades.
 
Kendyl318

Kendyl318

Location
Sacramento
I have never changed the charge coil before. Does anyone have a link to a video or other advice to change it? thank you guys for the information
 
Downrange

Downrange

Location
Northern michigan
Was it running good before.. If it was look to a mechanical issue that would cause this like ring end gap. To tight and this happens. Easy to check and fix if done early. Pull the head and look for light scoring to the cylinder, if it’s there pull the cylinder and gap the rings.
 
Jcary85

Jcary85

Site Supporter
Location
Glenmoore pa
Can you be more specific about how it slowly starts to die? Does it run ok but just lose power then eventually quit? Does it sputter, run like crap then die? What happens if you immediately try to start it? Does it fire at all or just turn over and do nothing? How long do you have to wait before it restarts and do you have to prime/choke/crank it a lot to restart it?

Couple other things to check:
-gas tank vent clog
-return line hooked up to incorrect spot on tank (I recently had a senior moment and hooked a return to a feed tube. Ski ran for 5-10 mins then quietly shut off...)
-cooling clog. Perhaps it’s actually overheating (though the Cdi is supposed to just lower rev limiter a lot). How hot does the motor get?
 
Kendyl318

Kendyl318

Location
Sacramento
Jcary85 said:
Can you be more specific about how it slowly starts to die? Does it run ok but just lose power then eventually quit? Does it sputter, run like crap then die? What happens if you immediately try to start it? Does it fire at all or just turn over and do nothing? How long do you have to wait before it restarts and do you have to prime/choke/crank it a lot to restart it?

Couple other things to check:
-gas tank vent clog
-return line hooked up to incorrect spot on tank (I recently had a senior moment and hooked a return to a feed tube. Ski ran for 5-10 mins then quietly shut off...)
-cooling clog. Perhaps it’s actually overheating (though the Cdi is supposed to just lower rev limiter a lot). How hot does the motor get?
Click to expand...
The best way I can describe it is this: it runs just fine without any sputtering, croaking or anything. After about 10 minutes, I will grab the throttle and when I try to give it gas it will run at 95%....then 80%.....then 50% and then eventually when I try to give it gas it will just shut off. But when I try to start it again, it will idle just fine but if I attempt to give it gas again it will shut the motor off
 
Desk_jockey

Desk_jockey

Location
Detroit metro
I am voting clogged vent line. Its running for 10 minutes getting all the fuel it needs before the vacuum is too great and the fuel supply stops. I have seen this before on other small engines where the gas cap vent goes bad and the engine will run perfect if the gas cap is loose allowing a vent. Tighten the cap and the engine will only run for a few minutes before vacuum is created.

Clogged filter symptoms are very similar also.
 
Kendyl318

Kendyl318

Location
Sacramento
Thank you for all of the suggestions. I am heading to the lake tomorrow to test out some repairs. I have ruled out all engine suspicions. I am thinking it is a few things. 1. Bad CDI. 2. Bad Coil inside ignition box. 3. Bad stator. I am going to leave the carb alone until the last because it was professionally rebuilt a few months ago but if it comes down to it I will rebuild again if my other suspicions do not fix the problem. I am going to swap out suspicions 1-3 tomorrow and ill keep you guys posted. Does anyone have a video link on how to replace a stator? again I have a 1994 701 Yamaha WaveBlaster. Thanks again
 
hornedogg79

hornedogg79

dodgin' bass boats
From your description it sounds like an exhaust leak or fuel delivery problem. You usually have spark or you don't. A bad cdi or stator may lose spark then regain it, but normally after it has cooled down. Not immediately.

Have you pulled the hood when it quits to look for smoke?

Check the internal filters on the pump side of your carbs, in line filter, and check tank for debris.

Sent from my SM-G930V using Tapatalk
 
Kendyl318

Kendyl318

Location
Sacramento
UPDATE: Took it out on the lake and it had the same issue with the new cdi so I ruled out cdi. Next I swapped out the in line fuel filter (a lot of debris) and that helped! It didn’t die like it normally does, but still running at about 70-80% capacity (as if it’s struggling a little bit). I replaced all the fuel lines with blowsion translucent and gonna check the carb pump to see if any debris is in there.
 
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