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1990 Yamaha 225 Stalling at idle speeds

jrzvike

jrzvike

New member
This is a saga. I have a 1990 21' Starliner with a 1990 Yamaha 225 ETLD model. Runs beautifully when under way and at idle. Three times today, when I went from idle to slow speed in a no wake zone or to pick up a skier, she would die. I would crank motor for several seconds and nothing would fire. Wait twenty minutes, crank it and she would fire up and run great. Never dies under way at above idle/no wake speeds. Sometimes it runs smooth at no wake speed, other times (3 times today) it dies and then I have to remove coweling and wait twenty minutes to restart. It has had this problem for some time now. Carbs have been rebuilt/cleaned 3 times at two different marinas, new plugs, compression good, new fuel water seperator, kill switch checks out, fuel filter replaced, I am running out of ideas and it is very frustrating. Any ideas out there? Thanks mates...
 
Addition

I should also add that it doesnt matter if I am running off onboard tank or new portable tank w/clean fuel...same result.
 
I feel your frustration. I've been fighting with my 200 Johnson since I got it from a crook on ebay, if I had any sense I'd have long ago parted it out but I'm just too darned stubborn to give up and admit defeat.

First off do you have a factory service manual for your specific engine? The Solec, Clymer, and other generic manuals leave a lot to be desired, get a real live factory manual if you can possibly find one.

It's possible an ignition component is going bad, affected by heat. You can get a spark tester at most any auto parts store for under $10 - my suggestion is to let the engine run on muffs for 20 or 30 minutes at a fast idle to get everything under the cowling nice and warm (hopefully 'till the problem shows up), then check to see if you've got spark on each cylinder (a healthy ignition system should be able to have a spark jump a 7/16" gap on the spark tester).
 
I had a issue like this with my merc. it was the stator, it has high and low speed windings. the low speed windings would short out when it got hot. it would run perfect over 1000 rpm. under 1000 rpm it would shut down like you turmed off the key. I dont know if the yammies are the same set up. But if you have a manual look up how to test the stator, that could be your issue. Hope that helps a little.
Good luck with it
 
I had the same motor on my Starliner. They are a great engine and not prone to problems. I have run carbed Yammies for years. Rarely break down. My guess is it is something simple. First you need to determine if it is fuel or electrical. Next time it stalls have a spark tester ready and see if you are getting a spark when cranking. Chances are it is not just one plug or it would run rough not stall.
The motor has a microprocessor called a YEMS that controls almost everything including the timing. It in itself is rarely ever the problem. It is responds to inputs from sensors. You would need to get a Yamaha shop manual (from dealer... good investment anyway) and test out the sensors. Not hard to do but you need the manual. Also sometimes you get a bad coil or plug wire but as I said it would run rough first if it was only one. In fact this system rarely fails period.
If you have good spark then your problem is fuel (my guess). It sounds like it might be flooding. Make sure the red lever on the Primestart (automatic choke) is not open. That would be dumping gas into the top 2 cylinders. The other possibility is a fuel pump with a bad diaphragm dumping fuel into one of the cylinders. If they have not been changed they should be anyway as they might be 21 years old.
But get the manual. You need to know how the engine functions to troubleshoot it. A good mechanic should have been able to troubleshoot this problem in an hour.
 
Additional troubleshooting performed...Thoughts?

Got to do a little troubleshooting today. Since the motor is only stalling when advancing throttle from idle, I took a look at the throttle position sensor. While performing the ohms check, I noticed that for the first 30-40 degrees of throttle travel, the ohms actually DROPPED a few ohms instead of increasing. Once the throttle plate hit the 30-40 degree position, then the ohms steadily increased from low 400s to 2.3k ohms. I thought the sensor was bad. When I looked at the throttle sensor while having someone else move the throttle, I noticed no movement at all on the sensor until they hit the 30-40 degree mark while advancing the throttle. The minimal drop in ohms when initially throttling might explain the motor dying, but why does it not start for another 20 minutes or so? Also, is there an adjustment on the throttle lilnkage or cable that will allow me to get rid of the "dead travel" when initially getting under way with the throttle. It also explains how I was able to keep it from dying if it felt like it was going to die, I would advance the throttle forward and it would sputter and then take off. This may be simple math to you, but it is trigonometry for me.
 
Thanks! Just for additional info. I had replaced the YEMS with no change, so yes I have an extra control unit now (around $600)...If I can figure out the TPS problem, I will look at changing out the fuel pumps next.
 
The TPS is very important on that motor since it is responsible for advancing the timing as well as opening the butterfly valves. It is possible if the TPS voltage dropped for it to retard the timing and stall the engine. However, if the throttle plates are not actually moving then that makes no sense that the voltage would drop. Secondly, you should be able to restart the motor immediately by simply advancing the throttle till the TPS advances. Let me know exactly what voltage you get at min and max throttle and the whatever drop you get when you initially advance throttle. I will check the manual when I get home.
I still think you need to get a spark test when it is not starting, and you could put a timing light on it and see if you if it is retarding instead of advancing. You do not want to start chasing ghosts. You need to troubleshoot step by step.
 
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