2011 F50 always stalls on the first startup attempt

[rejesterd]

SOLVED: Replacing the sensor assembly resolved the issue.

This is bothering me, but maybe it's normal.

I have 2011 F50 with almost 250 hours on it (I read the hours with YDS, and there are no current/recent codes). Every time I try starting it up in the morning, it always stalls on the first attempt. By that, I mean the engine starts up, runs for a few seconds, then putters/stalls out. The second time I start it, it always stays running.

I've tried pumping the bulb as much as possible, waiting 60 seconds, pumping it again, turning the key to On, wait another 30 seconds or so, then pump the bulb one more time. And it's not like the bulb is very squishy to begin with.. it stays pretty hard all the time, so I don't think I have a leak in the fuel hose.

Is this normal? If most other people experience this, I'm not going to worry about it, but it does seem odd that the engine never stays running the first time. Again, I don't see any codes from YDS, so I'm kind of lost.

Thanks again for the help.. I'm learning.

[boscoe99]

It is not normal.

Pumping the primer ball should be doing no good at all. There is sufficient gasoline remaining in the VST so the motor can get started and run for the time needed for the lift pump to refill the VST. The motor should start and run under any conditions, the same as with your modern EFI automobile.

If the motor starts and runs just fine after the second start, or anytime during the day since the motor will have been warmed up, my thinking is that something is amiss with Primestart system whereby extra gasoline is added to a cold motor to facilitate a cold start. I might suspect the engine temperature sensor. Or perhaps the idle speed control valve. Or related wiring.

Before you start the motor first time in the morning, what does YDIS say about the engine temperature? Does the temperature agree with the weatherman for your area?

But I am just guessing.

[99yam40]

have you been using the ringfree and other additives in the wrong dosage?
Just kidding

but seems like the ECU should control better and raise RPM and increase fuel for a cold motor and then adjust back to normal once warmed up.

Boscoe does an EFI have a prime start system?
I thought that was on carbed motors

[rejesterd]

It is not normal.

Pumping the primer ball should be doing no good at all. There is sufficient gasoline remaining in the VST so the motor can get started and run for the time needed for the lift pump to refill the VST. The motor should start and run under any conditions, the same as with your modern EFI automobile.

If the motor starts and runs just fine after the second start, or anytime during the day since the motor will have been warmed up, my thinking is that something is amiss with Primestart system whereby extra gasoline is added to a cold motor to facilitate a cold start. I might suspect the engine temperature sensor. Or perhaps the idle speed control valve. Or related wiring.

Before you start the motor first time in the morning, what does YDIS say about the engine temperature? Does the temperature agree with the weatherman for your area?

But I am just guessing.

Thanks, that is the behavior.. after the first startup, it always starts up fine for the rest of the day. And it's been that way since I bought it last year.

I'll hook up the YDIS before I start it next time. Certainly makes sense that it would be related to a temperature sensor, since it only seems to be a problem after sitting in the cold over night.

The only thing I can add is that I did have one code that occurred around 200 hours (so well before the end of last season, but certainly after the issue had already started). It was a #37 "instake air passage". But it only occurred that one time and never again after that.

I did remove and quickly inspect the thermostat last fall, but I never checked the temperature sensor. And I don't think me removing the thermostat caused the issue, because it was happening before then.

I'll try reading more about the Primestart system (if I can find any materials).

[rejesterd]

have you been using the ringfree and other additives in the wrong dosage?
Just kidding

but seems like the ECU should control better and raise RPM and increase fuel for a cold motor and then adjust back to normal once warmed up.

Boscoe does an EFI have a prime start system?
I thought that was on carbed motors

haha I knew that was coming.

It does seem like the rpms drop too quickly just before it stalls out. As boscoe noted, it could be an issue with the temperature sensor. So I'm going to check that out.

[rejesterd]

Also for reference, I thought I might just post my recent YDIS report. I did this a couple weeks ago. The engine was already warmed up when I did it, so it won't help determine if there's an issue with the temperature sensor. But maybe there are other oddities that I didn't pick up on, so I figured I'd share it:

Diagnosis,
,Code,Item,Result,Condition,
,13,Pulser coil,Normal,,
,15,Water temp sensor,Normal,,
,17,Knock sensor,Normal,,
,18,Throttle position sensor,Normal,,
,19,Battery voltage,Normal,,
,23,Intake temp sensor,Normal,,
,28,Shift position switch,Normal,,
,29,Intake press sensor,Normal,,
,37,Intake air passage,Normal,,
,44,Engine stop lanyard switch,Off,,
,49,Over cooling,Normal,,

Diagnosis Record,
,Total hours of operation,244,
,Code,Item,Occurred,
,37,Intake air passage,201.4,

Engine Monitor,
,Monitor Item,Result,Unit,
,Engine speed,742,r/min,
,Intake pressure,38.17,kPa,
,Intake pressure,11.38,inHg,
,Atmospheric pressure,1065.3,hPa,
,Atmospheric pressure,31.5,inHg,
,Ignition timing,ATDC 10,deg,
,Battery voltage (12-16),14.70,V,
,TPS voltage (0.5-4.5),0.982,V,
,Throttle valve opening (0-90),7.1,deg,
,ISC valve opening,33,%,
,Fuel injection duration,1.94,ms,
,Water temperature (below 90),62.5,°C,
,Water temperature (below 194),144.5,°F,
,Intake temperature (below 70),33.7,°C,
,Intake temperature (below 158),92.7,°F,
,Engine stop lanyard switch,OFF,,
,Shift position switch,ON,,
,Oil press switch,OFF,,
,Dual engine system switch,OFF,,

Data Logger[Engine operating hours according to engine speed],
,Engine speed,Time[h],
,- 1000 r/min,128.8,
,1000 - 2000 r/min,62.5,
,2000 - 3000 r/min,15.8,
,3000 - 4000 r/min,12.0,
,4000 - 5000 r/min,13.0,
,5000 - 6000 r/min,12.7,
,6000 - 7000 r/min,0.0,
,Engine hours,244,

Data Logger[Data comparison graph],
,Engine speed[r/min],Battery voltage (12-16)[V],TPS voltage (0.5-4.5)[V],Water temperature (below 90)[°C],Intake pressure[kPa],Oil press switch[0:OFF 1:ON]
,5750,14.58,2.48,53.8,83.9,0,
,850,14.14,1.02,62.5,39.5,0,
,800,14.43,1.00,61.7,39.0,0,
,1050,14.87,1.05,61.7,40.5,0,
,750,14.28,0.98,61.7,40.0,0,
,750,13.70,0.98,50.6,40.0,0,
,700,13.99,0.98,60.8,40.0,0,
,750,14.28,0.98,61.7,40.0,0,
,700,14.58,0.98,61.7,38.5,0,
,700,14.79,0.98,62.5,39.5,0,
,700,14.87,0.98,62.5,39.0,0,
,750,14.87,0.98,62.5,38.5,0,
,750,14.94,0.98,62.5,38.5,0,

[99yam40]

Make sure the pressure readings agree with the weather station also

maybe Rodbolt can give thoughts of the print out.

If he cannot see it properly on his old laptop I will try to repost a section of it .
,742,r/min,
,Intake pressure,38.17,kPa,
,Intake pressure,11.38,inHg,
,Atmospheric pressure,1065.3,hPa,
,Atmospheric pressure,31.5,inHg,
,Ignition timing,ATDC 10,deg,
,Battery voltage (12-16),14.70,V,
,TPS voltage (0.5-4.5),0.982,V,
,Throttle valve opening (0-90),7.1,deg,
,ISC valve opening,33,%,
,Fuel injection duration,1.94,ms,
,Water temperature (below 90),62.5,°C,
,Water temperature (below 194),144.5,°F,
,Intake temperature (below 70),33.7,°C,
,Intake temperature (below 158),92.7,°F,

[boscoe99]

Make sure the pressure readings agree with the weather station also

Ditto on that. I just noticed the 31.5" Hg indication. Seems exceptionally high unless he is boating in the dead sea.

[rejesterd]

Make sure the pressure readings agree with the weather station also

I'll do that.

I did just look at the weather history, and on the day I did the test, the weatherman reported 29.8 in of pressure. My sensor was reading 31.5. So that's definitely off, I just don't know if it's enough to make a difference.

[99yam40]

if it thinks it is at a different altitude, it changes the amount of fuel.
I would think while not running both pressure readings should agree with the weather man

[rejesterd]

Ok, so the pressure in Denver isn't even as high as what my sensor is reporting in NH.. so it seems this is the culprit. I'll confirm by taking another measurement when the engine is totally cold.

Edit: After further reading, I found the place in the service manual that tells you to replace the sensor assembly if the cold temp reading is off by more than 5 degrees C. So I'll check that this weekend, then order the part if the readings are still off.

I'm also going to check the water cooling temperature sensor, because the readings on that don't make sense to me either. Why would it go as low as 50.6 and eventually level out at 62.5?

Thanks again to boscoe and others. I'll update the thread when I have more news.

[boscoe99]

Ok, so the pressure in Denver isn't even as high as what my sensor is reporting in NH.. so it seems this is the culprit. I'll confirm by taking another measurement when the engine is totally cold.

Altitude should not be confused with air pressure. Air pressure decreases with altitude. There will be less air pressure in Denver than in NH.

But if the sensor is reporting higher than normal air pressure that should cause the ECU to increase the fuel flow. Not decrease the fuel flow.

Now with respect to temperature, there should be more fuel flow with low temperature and less fuel flow with higher temperature.

[rejesterd]

Altitude should not be confused with air pressure. Air pressure decreases with altitude. There will be less air pressure in Denver than in NH.

But if the sensor is reporting higher than normal air pressure that should cause the ECU to increase the fuel flow. Not decrease the fuel flow.

Now with respect to temperature, there should be more fuel flow with low temperature and less fuel flow with higher temperature.

Noted, but 31.5in is still really high.. no US city has ever recorded a pressure that high, as far as I can tell. Also, the intake temp is quite high (92F).. I still need to do the cold test, but I'm thinking the temperature portion of the sensor assembly could also be broken.

If I understand correctly, you're suggesting that if the temperature sensor is reading too high or the pressure sensor is reading too low, then I won't get enough fuel flow. But if they're both reading too high, would you agree that could give the same bad result (i.e. not enough fuel flow)?

[99yam40]

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

[rejesterd]

Can you post (even maybe under your signature), a full model # ?

I actually don't know the full model #. I keep forgetting to take a picture of the ID tag on the engine. I'll do that and update my signature soon (I'm just not near my boat at the moment).