Cold start problems, Yamaha 20HP 4-stroke

[rseas]

I run a newer Yamaha 20HP 4-stroke. Love the motor, its quiet, no smoke, is very smooth running and gets great economy (1-2 gallons per day fishing fresh water and 2-3 gallons per day trolling the salt). Over all it is a very reliable prop turner. The key here is “overall”. All though the motor starts on the first or second pull every time, when cold it runs for a while then sputters out. The stalling only occurs when the engine is cold. I have checked the tank vent and all is well. I have observed the filter bowl while the problem is occurring and the filter bowl is full of fuel with no significant bubbles. If you rev it up at just the right time you can nurse it past the difficult period but this is very inconvenient. I am out of ideas and was wondering if anybody has any ideas for correcting the problem. The motor is still under warrantee but I was hoping to avoid a trip to the Everett waterfront for warrantee repairs

[bassmasterderek]

I have the same problem with my brand new 40hp 4-stroke yamaha. It is a great motor but don't like the cold. I usually just let it idle for about 5 minutes before I rev it up at all. no problems in the warmer weather for me though!

[Coastfishin]

I have a 2year old Merc 15hp 4-stroke. It does the same thing, has ever since it was new. Just like an old Ford, gotta warm it up before it will move!

[DaKanati]

Is it choked when this happens? I have a one year old yamaha high thrust 8 hp and I usually let it run on choke for about 30 seconds then half choke for a couple of minutes then I take the choke fully off. If its really cold and it sounds like it is going to load up and die again Ill just pull the choke out half way for another minute or so. Basically you probably just need to monitor it while it warms up.

[Anglinarcher]

I am actually glad to hear that I am not the only one. My Merc 90 HP is a real bear until it warms up the first time on a cold day. After I get it heated up, it starts within a second of the key turn.

I suspect that this is normal with our motors, and that except for allowing it to warm up under choke for a few seconds to a minute or so when you start on a cold day, "it is what it is".

[hewesfisher]

I am actually glad to hear that I am not the only one. My Merc 90 HP is a real bear until it warms up the first time on a cold day. After I get it heated up, it starts within a second of the key turn.

My 90hp Merc is the same way, worse than getting my old Ford running on a cold day, but once it's going, and I can stop fiddling with the mixture enrichment feature (no choke on mine) to keep it running, then it's just keeping an eye on the tach and bumping the throttle down until it will run at 1200 - 1500rpm. My 6hp 4-stroke Merc kicker, on the other hand, is a little easier to cold start, but it's still not pull and go.

[Bogey]

Sorry, don't know what to tell you that will help with your motor, but I can say that I ran a merc 60hp 4-stroke from 2001 - 2007 and it started and ran PERFECT in temps going down to -5! I NEVER had a cold issue with it? Best of luck - I hope you get it smoothed out.

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I run a newer Yamaha 20HP 4-stroke. Love the motor, its quiet, no smoke, is very smooth running and gets great economy (1-2 gallons per day fishing fresh water and 2-3 gallons per day trolling the salt). Over all it is a very reliable prop turner. The key here is “overall”. All though the motor starts on the first or second pull every time, when cold it runs for a while then sputters out. The stalling only occurs when the engine is cold. I have checked the tank vent and all is well. I have observed the filter bowl while the problem is occurring and the filter bowl is full of fuel with no significant bubbles. If you rev it up at just the right time you can nurse it past the difficult period but this is very inconvenient. I am out of ideas and was wondering if anybody has any ideas for correcting the problem. The motor is still under warrantee but I was hoping to avoid a trip to the Everett waterfront for warrantee repairs

Sounds like a choke adjustment to me. I assume you have an automatic choke and the problem occurs as the motor starts to warm. I would plan a trip to Everett in the near future and have whomever make the necessary adjustments.

[Easy Limits]

This is a very common issue with Yamaha 4 strokes. I have had two Yamaha 15 HP four strokes. They tend to be a little cold blooded. Just make sure you warm them up good before you pull away from the dock.

[rseas]

A quick follow-up, just picked the boat up from Boondocks in Bellingham. Their mechanics are Yamaha 5-star certified and they were closer to home than the outfit in Everett. They seem like a great bunch of guys and they will have our future business (both boats). The long and short of it is that they fixed my cold start problem for no charge. It turned out to be an air/fuel mixture problem with the low speed jet. This is not considered owner adjustable and to meet emission requirements must be modified by an authorized Yamaha mechanic. I was impressed with their level of expertise and more importantly their customer service.

They went out of their way to resolve a warrantee registration issue for us. The dealer that we bought the motor from did not file the warrantee paperwork with Yamaha and had since gone out of business. Boondocks took the time to try and contact the original sales person (in the Portland area) and Yamaha. It turned out that Boondocks had to file an exception to our warrantee registration with Yamaha and take responsibility for our motor as the delivering dealer.