2011 F50 always stalls on the first startup attempt

[99yam40]

I would not want to keep anything over the 28" upper limit here in Texas, the smaller 20" are better eating anyway.
did you cook a trytip or not

[pstephens46]

Cooked the tri tip Friday.

[rejesterd]

It's an F50TLR. I dunno how a 150 came into this discussion.

[boscoe99]

What does a motor have to do with a conversation about fishing and eating?

[99yam40]

rejesterd did you get any numbers when you hooked up to it last time or not?

By the way, what is the elevation of the local station that is closest to your boat? The higher the elevation the lower the atmospheric pressure.

a few miles going up a mountain from the coast can make a big difference

I guess Rods input on the link and sync would still be true even thou he may or maynot have been referring to a F150 instead of a F50.
maybe he will chime in on that to make it clear

[pstephens46]

What does a motor have to do with a conversation about fishing and eating?

This was a lull in the storm.

[boscoe99]

This was a lull in the storm.

So, now you want to make this thread about storms? A perfect storm or a less than perfect storm? Don't lull us to sleep with your response. Let us know how you really feel about it. Whatever it, is.

Storms by the way bring pressure changes. Absolute pressure changes. Absolutely they do.

[rejesterd]

rejesterd did you get any numbers when you hooked up to it last time or not?

This morning (and yesterday morning) before I started the engine, the pressure sensor read 29.3inHg. The local station (which is less than 2 miles away and at the same elevation) reported 30.0inHg. After warming up the engine for 10 minutes, the pressure reading was exactly the same (29.3). A couple weeks ago, it was reading 31.5, and the weather station at the time was reporting 29.8.

However, the temperature reading was well within spec (i.e the range Yamaha notes in the service manual: plus or minus 9 degress F) when I took a reading before starting the engine this morning.

Although the test on the sensor passed for temperature, the fact is that I've never seen an accurate pressure reading. Sometimes it's too high (like a few weeks ago) and sometimes it's too low like it is now.

I'll be checking the connections with a multimeter shortly, but if those look good, I'm going to replace the sensor assembly. The relevant points of data I have are:

1. I've never observed a correct pressure reading. And it's also inconsistent.. sometimes it's too high, sometimes it's too low.

2. I had a code #37 (intake air passage) at 201 hours. Rodbolt confirmed that this could have been the result of a bad pressure reading ("intake air passage simply means the ECU did not like the air pressure reading while compareing it to other sensor inputs").

3. I had a code #29 just last week at 245 hours. Code 29 is related to the pressure sensor specifically.

I agree it still could be a ghost, but I want the pressure to read correctly regardless.. so my next step will be to replace the sensor assembly.

[pstephens46]

So, now you want to make this thread about storms? A perfect storm or a less than perfect storm? Don't lull us to sleep with your response. Let us know how you really feel about it. Whatever it, is.

Storms by the way bring pressure changes. Absolute pressure changes. Absolutely they do.

So storms are relevant after all.

[99yam40]

rejesterd,
as Rod said before, check the reference voltage to make sure something is not drawing it down sometimes.
If it is not consistent the return to ECU will not be either.

seems like it is not off the same way all of the time, some over and some under.
It would be interesting to see what the reference voltage is when it is at those opposite sides of weather report

[panasonic]

After reading the whole thread, I have questions. I cannot understand why the engine after the first failed start would work normally for the rest of the day? If it had a bad MAP sensor or air temp sensor would it not stay bad all the time. Seems strange it would do the exact same thing everytime?

I wonder if it is a bad connection somewhere that causes a erroneous reading when cold on the first start, then fixes itself after some current flows through it.....I don't know much about these systems, but I do know bad connections cause some awfully weird things to happen to electronic components.

[99yam40]

Bad connection = high resistance which = lower voltage getting to someplace

[rejesterd]

After reading the whole thread, I have questions. I cannot understand why the engine after the first failed start would work normally for the rest of the day? If it had a bad MAP sensor or air temp sensor would it not stay bad all the time. Seems strange it would do the exact same thing everytime?

I wonder if it is a bad connection somewhere that causes a erroneous reading when cold on the first start, then fixes itself after some current flows through it.....I don't know much about these systems, but I do know bad connections cause some awfully weird things to happen to electronic components.

I should note that on Sunday (yesterday) it actually started the first time in the morning. However yesterday morning was much warmer than it has been on my previous startup attempts. I don't actually recall how often it would start on the first try last season, but the issue definitely correlates with sitting overnight, specifically in cool, dry air (as opposed to just sitting for a certain amount of time).

But I agree, it doesn't make sense that it would be a pressure sensor issue, because it doesn't happen all the time. But then again, it makes no less sense than any other explanation that's been presented to me. Whether it's a link/sync problem, a sensor problem, a voltage problem.. I don't see why those things would only happen once on a cool morning and never again after that for the rest of the day (and sometimes the rest of the weekend, if the morning is warm enough).

What I'm wondering now is if this is related to my rough idle issue. Yesterday I was able to compare another running F50 (almost the same model year) and it didn't shake nearly as much as mine at idle. I think I'm going to just end this thread for now and make a new one for the rough idle issue, because that's more important to me right now.

[99yam40]

you really need to follow the link and sync procedure in service manual before doing anything else. Every motor needs the basic setting to start out with and Rod said yours was off.
Hope fully it is that simple

[rejesterd]

you really need to follow the link and sync procedure in service manual before doing anything else. Every motor needs the basic setting to start out with and Rod said yours was off.
Hope fully it is that simple

I would love to, except I don't have the exact service manual for my model year (2011). I found a 2004 manual for the EFI models like mine, so it's close, but I don't see anything in there about "link and sync".