2011 F50 always stalls on the first startup attempt

[rejesterd]

if the Pressure reading is too high it thinks there is more O2 available so it gives more fuel.
If the temp is too high it thinks the motor is already warm so it will cut back on the normal cold enrichment

you do not have to really understand it all, just make sure the sensors are reading correctly

the motor is sucking air in from around a warmed up motor, so the air temp it is sensing will be warmer that the air out in the open.
Just my thoughts

Agreed, the temp reading for a warmed up, running engine should be warmer than the ambient temp. So I just need to do the cold test to confirm if it still reads high.

And I know I don't need to understand, but I enjoy understanding things when/where possible :P

[rodbolt17]

31.5 is rather normal here in the outer banks.
33% ISC is to low.
have the link and sync done correctly.
have the intake area checked for any air leaks.
make sure all the rubber caps are in place on the intake nipples.

[rejesterd]

31.5 is rather normal here in the outer banks.
33% ISC is to low.
have the link and sync done correctly.
have the intake area checked for any air leaks.
make sure all the rubber caps are in place on the intake nipples.

Thanks. I did look at the weather report for the day when I did the test, and it said the pressure was 29.8.. so I still think I should check the sensor assembly (as it's easy enough to do when the engine is cold).

I was trying to find more info about what a normal ISC opening should be. What is considered a normal percentage when idling? Maybe that was the one active YDS test that I skipped because it said it would take about 30 minutes.

I'll read more about doing the link and sync, and do that after testing the sensor assembly.

[boscoe99]

A "standard" day is 29.92" Hg. 59 degrees F. At sea level.

Current pressure at Portsmouth NH is 29.95" Hg. A bit nippy at 52 degrees f.

Just click on a dot in your state closest to you and get more accurate data. I believe you indicated you are in New Hampshire.

METAR TAF : Portsmouth International Airport at Pease, Portsmouth New Hampshire United States

[rejesterd]

Yeah, I got my number from a local station that's about 5 miles from where my boat is docked. Based on that and the history of the region in general, I think the engine's reading of 31.5 is definitely high. The cold test will confirm, and I'll just go from there.

[rodbolt17]

have the link and sync done properly and it will work.
quit hunting wabbits and chasing ghosties.
the ISC% is rather low and the TPS is way out of whack.

[rejesterd]

have the link and sync done properly and it will work.
quit hunting wabbits and chasing ghosties.
the ISC% is rather low and the TPS is way out of whack.

I agree, the sensor assembly might be a ghost in relation to my startup problem. But the fact is, the pressure sensor was reading high that day. No nearby weather station reported a pressure higher than 29.8. Since this sensor is very easy to check, I'm going to check it. If the cold test shows it's out-of-spec, I'll replace it.. but I won't assume that's going to fix my startup problem.

I don't know what "link and sync" means exactly. The service manual says the throttle link rod should be a certain length, so I can check that. But I assume there are other steps..

[rodbolt17]

do what you wish.
there are several tech bullitens on how to correctly set up the linkage.
I just happen to own an F150 and I happen to fix outboards on a daily basis.
I did pass the Yamaha master tech test in march of 06.
31.5 is a normal reading here on the banks.
like I said quit chaseing wabbits and ghosties.
29"Hg means we gots us a hurricane.

[rejesterd]

do what you wish.
there are several tech bullitens on how to correctly set up the linkage.
I just happen to own an F150 and I happen to fix outboards on a daily basis.
I did pass the Yamaha master tech test in march of 06.
31.5 is a normal reading here on the banks.
like I said quit chaseing wabbits and ghosties.
29"Hg means we gots us a hurricane.

I get that you have lots of experience, but you're basically saying that all the weather stations I checked are wrong. I seriously doubt that.

Also, if all you can do is talk to me like I'm a baby, and not technically explain why the TPS is "way out of whack" (when it's exactly in the middle of the spec range, 0.8-1.2), you're wasting my time. If you have a link to one of those tech bulletins, great. Otherwise, go tell someone else to stop thinking and just do what you say.

[rejesterd]

I just connected the laptop this morning when the engine was cold, and I got a code 29 "Intake pressure sensor". I'm going to check the connection later to make sure nothing is funny with it, but if not, I'll just try replacing the sensor assembly and go from there.

Thanks again to boscoe and others.

[99yam40]

what did the intake pressure not give any read out when cold?
what about the Barometric Pressure/atmospheric pressure sensor,
how far apart were the 2 readings?

I believe the Barometric Pressure/atmospheric sensor was the one that was reading off from the weather station.
29.92 is normal sea level pressure from what I read on line, but then corrected will read a little higher.
the weather station hanging on a wall in my house says it is 30.25 right now here in Texas a few miles from the coast.
On line says it is 29.94

[rodbolt17]

I have never seen a map sensor fail.
I have seen low ref voltage that can make it do dumb stuff.
intake air passage simply means the ECU did not like the air pressure reading while compareing it to other sensor inputs.

it is a simple sensor to test.

[rodbolt17]

todays baro pressure on the outer banks is now 30.09 and rising.
was a good day for the pistol action shoot.

[99yam40]

todays baro pressure on the outer banks is now 30.09 and rising.
was a good day for the pistol action shoot.

Do you wear gloves or end up with lots of power residue on your hands?

I ran out to the bay this morning, way too many people out there on weekends.Made me remember why I go during the week normally.
Did not see even one red on the flats. did pick up one undersized blind casting though.
Op sounds like you need to be checking the reference voltage.

But would both of the pressure sensors get the same reference voltage to throw them both off the same maybe?

[rodbolt17]

it is a simple 3 wire sensor.
needs a 5v ref,a ground and a pick off voltage.
at key on the ECU locks that baro pressure,it can rise but not fall.
once running the ECU assumes the baro did not change and now looks at intake air pressure.
typically code 29 means something else is wrong.
like I said I have seen code 29 many many times yet have never seen a bad sensor.

my bet is the linc and sync were never properly done OR somebody has monkeyed with it.
I like to see an ISC request of about 38-40% with a TPS voltage of about.7-.72V and a stable idle of about 700-750 RPM.
if everything is correct it can be done.
at .9v and a plate opening of 7* and the ISC at 33% means something is not set up correctly.