How does your cold 4 stroke start?

[Coastalcav]

Hey all, 2017 F90LB here. Ever since I got this boat and motor (had 50 hours at the time) if I let it sit more than a couple days, it always takes 2 starts to fire up. First try it starts and runs for about 2 seconds, then dies. It ALWAYS starts and stays running after that second try, so I do not think it is a problem with the outboard itself, moreso just wondering if this is something common cold start behavior for a lot of folks when their outboard sits for a while. It takes 2 tries if it sits for 2 days, or 2 months. I have tried priming as the owners manual suggests for "starting procedure" but it makes no difference.

I realize this may be completely pointless to post about, but would appreciate any opinions

[99yam40]

I do not have an injected outboard motor, but I would expect them to start and run like a car or truck injected motor and not die after starting

[boscoe99]

Ditto. Something is wrong.

[99yam40]

does it start up at high RPM and then drop lower?
Maybe the IAC valve is sticking, and not resetting to 100% open at shutdown (if it has one)

Or maybe the VST is draining fuel back out or fuel evaporating away causing very low fuel level in VST

monitoring rail pressure might help you figure out what is happening

[brian3006]

I have 2 boats that have F90 on them. One is a 2005 and the other is a 2011. Both of them start just fine when cold. both of them are used more frequently in the winter months, so cold starts in 20 degree weather is common for them. Both of them start just fine and stay running. But if you put them in gear and try to rev the engine too soon they will both die. (like if trying to back off of a trailer). if you let them idle and warm up for about 1-2 minutes...no problem whatsoever.

[DennisG01]

How long have you had the engine (and how many hours)?

[Coastalcav]

How long have you had the engine (and how many hours)?

I have had it for about a year and it has 67 hours currently

[Coastalcav]

Thank you all for the responses. When I first start it cold, it will sit at 1000, 1100 RPM or so before it dies after a second or two. Then on the second start where it stays running, it drops right down to 8-900 (regular idle speed)

[Coastalcav]

I have 2 boats that have F90 on them. One is a 2005 and the other is a 2011. Both of them start just fine when cold. both of them are used more frequently in the winter months, so cold starts in 20 degree weather is common for them. Both of them start just fine and stay running. But if you put them in gear and try to rev the engine too soon they will both die. (like if trying to back off of a trailer). if you let them idle and warm up for about 1-2 minutes...no problem whatsoever.

Interesting. I have not tried putting them in gear at all during startup, after the second start where it stays running I always give it a few minutes at the dock before I take off. Have not had it die yet during takeoff. I imagine if I gave it throttle during the first start it wouldn't die either, but I shouldn't have to.

[Coastalcav]

does it start up at high RPM and then drop lower?
Maybe the IAC valve is sticking, and not resetting to 100% open at shutdown (if it has one)

Or maybe the VST is draining fuel back out or fuel evaporating away causing very low fuel level in VST

monitoring rail pressure might help you figure out what is happening

Above post for RPMs, I wonder if the VST drains over time? I don't know exactly how many days I can go in between starts when it requires 2 starts, if I go one day to the next it doesn't need two starts, but sitting for multiple days seems to trigger it. I was hoping to experiment with the warmer weather coming here in Oregon, to see if it was also temp related. If we got a good long stretch of warm weather maybe the issue won't repeat itself.

Local Yamaha dealer said it's "just cold" and that it runs and idles fine after the second start so there's no reason for concern. Truth be told I do not like our local Yamaha dealer, I've seen some shoddy work come out of his shop and he seems more like a salesman than a mechanic.

[pstephens46]

Above post for RPMs, I wonder if the VST drains over time? I don't know exactly how many days I can go in between starts when it requires 2 starts, if I go one day to the next it doesn't need two starts, but sitting for multiple days seems to trigger it. I was hoping to experiment with the warmer weather coming here in Oregon, to see if it was also temp related. If we got a good long stretch of warm weather maybe the issue won't repeat itself.

Local Yamaha dealer said it's "just cold" and that it runs and idles fine after the second start so there's no reason for concern. Truth be told I do not like our local Yamaha dealer, I've seen some shoddy work come out of his shop and he seems more like a salesman than a mechanic.

Watch to see if 2 attempts turns into 4-6 and then you will need to do something. The putting into gear and stalling refers to starting and then, say, trying to back off trailer when motor is stone cold. Doesn’t apply to your situation. No, the VST should not drain. I’d keep an eye on it for now and see if it gets worse.
In the interim, find a mechanic that suits you. Plenty around here, but only two I trust.

[panasonic]

Should start and stay going first try..just like your car/truck. My F70 starts first time ,every time ,no matter the temperature.

[DennisG01]

I think, as you eluded to, this is more of a annoyance than anything else since it's been happening for so long and sounds like it hasn't gotten worse. However, I agree that it shouldn't be happening - especially with an injected engine.

I don't "think" your VST tank would drain out (unless maybe the screw is loose/has no gasket?), but it's easy enough to check. After running the engine, let it cool down a bit and then drain it into a glass jar. Note the amount and pour it back into the fuel tank (unless it's dirty, then that's another issue). Run the engine again for a few minutes then shut 'er off. Time this for when you won't be using it again for a few days. When you're back at the boat, drain the tank again before you start the engine and compare the amount.

It might hard to get a good read given the short duration, but I'd be curious about the fuel pressure before starting and during the "event", as well.

I would probably take a good look at the idle speed valve while starting the engine the first time and then the second time, as well. I honeslty don't know much about it on your engine, but I wonder if it's gummed up/sticky and it takes that first few seconds for it to "free up"? Maybe someone else can expand on that... or totally debunk it as a possibility!

[99yam40]

can anyone say if this F90 motor is like the F150 injected motor that you can hear the ISC valve rattle when you shut it down(resetting to !00% for the next start up?)

[Coastalcav]

I think, as you eluded to, this is more of a annoyance than anything else since it's been happening for so long and sounds like it hasn't gotten worse. However, I agree that it shouldn't be happening - especially with an injected engine.

I don't "think" your VST tank would drain out (unless maybe the screw is loose/has no gasket?), but it's easy enough to check. After running the engine, let it cool down a bit and then drain it into a glass jar. Note the amount and pour it back into the fuel tank (unless it's dirty, then that's another issue). Run the engine again for a few minutes then shut 'er off. Time this for when you won't be using it again for a few days. When you're back at the boat, drain the tank again before you start the engine and compare the amount.

It might hard to get a good read given the short duration, but I'd be curious about the fuel pressure before starting and during the "event", as well.

I would probably take a good look at the idle speed valve while starting the engine the first time and then the second time, as well. I honeslty don't know much about it on your engine, but I wonder if it's gummed up/sticky and it takes that first few seconds for it to "free up"? Maybe someone else can expand on that... or totally debunk it as a possibility!

Thanks for the reply, the VST looks easy enough to drain and at least I might be able to eliminate that as a possibility. I will do that next time it sits for a while and next time it runs. For sure just an annoyance at this point. As well as an extra start every trip out.