2003 F115 stalling/skipping and would not shut off once

[99yam40]

So, it sounds like they are not something that can be taken apart and cleaned up to fix the sticking,
or is it doable but not worth the time to the tech but can be done if an owner wanted to?

[boatmangc]

I have had luck cleaning Suzuki and Mercruiser as well as some automotive ISC/IAC valves but none with the Yamaha...
Good 24 hour soak in Power Tune usually does the others.

[99yam40]

Are you saying that you have tried on the Yamaha's but were not successful or you just have not tried any Yamaha's

[Sparkieboat]

I want to thank you all for your valuable words of wisdom. I will try a overnight soak and see if it works...worth a shot anyway. I only hope my ECU is not toast. I will preform the test outlined by rod and see if it works or not. it will be about 10 days before I can get back to it. I will repost then.
Thanks again Sparkie

[boatmangc]

Are you saying that you have tried on the Yamaha's but were not successful or you just have not tried any Yamaha's

Tried it on Yamis with no success.
Costs very little to try though

BTW Sparkie, from your posts there is no way out for you, you will need at least a thermostat and a manometer.
My offer still stands.

[Sparkieboat]

do you think 4 cheap vacuum gauges would work??

[boatmangc]

Relatively speaking, yes as long as they are all calibrated the same.
Seriously, I have more than one. I have the Vacuumate as well as a set of gauges.
I will be happy to let you use them, just PM me your info, set up your motor and send them back.
You'll spend on shipping what you will buying cheapo's from H. Freight or N. Tool.
Realistically once a 4 stroke EFI is set up properly it should NEVER need another shutter adjustment unless a spring breaks or something.
Just like timing on a 2 stroke, it never really changes unless some one monkeys with it.
So most likely you will buy them, set up your motor and then move them around in your toolbox for the next 10 years.
I work on outboards every day (except when I am working on my Hotrod) and only use my Vacuumate maybe twice a month.

[Sparkieboat]

so i guess it looks like someone may have been monkeying around with the shutter adjustment.
I just returned from my trip, I saw Rodbolts favorite place Venezuela, I only saw it while I was in Trinidad. I did not realize it was so close. I then spent 4 days in Guyana. I saw a lot of outboard motors there mostly mercury/mariner or yamahas, I did not see a single OMC motor. not sure why.
I will try soaking the ISC over night. see what happens.
Good to be home...God Bless America

[99yam40]

so i guess it looks like someone may have been monkeying around with the shutter adjustment.

Either something breaks or someone takes something apart
If there is a screw that someone can get to, someone will put a screw driver on it and move it around if they are having problems with the motor, just to see if they can make better, even if they have no idea what they are doing.

hope you get this motor running properly without too much expense.


Sparkie, I just happened to run across the place I read about the non Yamaha buzzer hooked up that caused some problems and I thought I would send it your way just for kicks.
http://forums.iboats.com/showthread.php?t=397729

Strange things happen when using parts other than what was designed for it.

[Sparkieboat]

I am going to reinstall the ISC today and see if the soaking worked. How will I know if it is working other than it not getting real hot??? Rod said I need to get my ISC to %45, I am not sure how to do that.

I have not messed with my alarm, but I find it very difficult to believe it would effect the engine in any way, unless it was bleeding power to the ground somehow, which would mean it was defective. but there does seem to be something to your claim. I will definitely keep that piece of info in my mind in case I ever run into that situation, maybe I will disconnect my alarm just for kicks, I am having a shut down issue.
Thanks for all of your input
Sparkie

[99yam40]

yea, not saying it is your problem, just thought I would back up what I was saying before about non Yamaha parts can cause problems.
Does not make any sense to me how that could have effected his relay unless it is run off of the 5v instead of the 12.



Remember Rodbolt's statement
"another test is simply listen for the ISC to chatter at engine shutdown.
that chatter is the valve resetting to 100% in anticipation of the next start cycle."

Could you hear the ISC rattle( reset) when turned off before you pulled it to clean?

I am not sure how hot those things get when working properly, but according to Rodbolt, it should get too hot when running test multiple times. Probably a good idea to shoot with a temperature gun like Rod said.

I was looking for the temp. that Rod said it will show if bad, but could not find it. Maybe that was in a different thread altogether.

Anyway, I reread some other posts here and #15 from Rod said
" your fuel pressue numbers look good.
leaking injector wont hold 38 PSI.
the spike when its stalling is the ISC is opening, thus dropping intake vacume thus cloesing the fuel pressure regulator thus spiking the rail pressure by about 5 PSI."

Makes me wonder if the ISC is working properly or sticking only sometimes, Just a thought

[Sparkieboat]

I definitely could hear something that could be described as a rattling each time motor shuts down, last maybe 1.5-2 secs. It would be nice to know exactly what temps I am looking for. Although I am not sure how hot it should get, it did seem unusually hot to me. The ISC is set at %60 when I just do a key on..then goes to %30 when I crank it. I am not sure what effects the ISC, or how to make any adjustment to it. Rod said I needed to get it to %45 and set the TPS to .733.
I still need to clean/replace the t-stat.

[Sparkieboat]

ISC was noticeably cooler today after 5 mins of run time. I would say that it was good and warm today, it was plum hot the other day after same time.

here are some readings the first is at 2100 rpms and about 2 mins of run time.

Save date March 31 2011
ECM No.: 68V8591A11

Engine Monitor
Monitor Item Result Unit
Engine speed 2162 r/min
Intake pressure 55.46 kPa
Intake pressure 16.42 inHg
Atmospheric pressure 990.9 hPa
Atmospheric pressure 29.3 inHg
Ignition timing BTDC 5 deg
Battery voltage (12-16) 14.1 V
TPS voltage (0.5-4.5) 0.831 V
Throttle valve opening (0-90) 3.3 deg
ISC valve opening 55 %
Fuel injection duration 2.28 ms
Water temperature (below 90) 38.5 °C
Water temperature (below 194) 101.3 °F
Intake temperature (below 70) 18.8 °C
Intake temperature (below 158) 65.8 °F
Engine stop lanyard switch OFF
Shift position switch ON
Oil press switch OFF
Dual engine system switch OFF



next reading was engine off after about 5 mins of run time.

Save date March 31 2011
ECM No.: 68V8591A11

Engine Monitor
Monitor Item Result Unit
Engine speed 0 r/min
Intake pressure 99.09 kPa
Intake pressure 29.33 inHg
Atmospheric pressure 990.9 hPa
Atmospheric pressure 29.3 inHg
Ignition timing - deg
Battery voltage (12-16) 12.3 V
TPS voltage (0.5-4.5) 0.709 V
Throttle valve opening (0-90) 0.2 deg
ISC valve opening 65 %
Fuel injection duration 0 ms
Water temperature (below 90) 32.9 °C
Water temperature (below 194) 91.1 °F
Intake temperature (below 70) 20.7 °C
Intake temperature (below 158) 69.2 °F
Engine stop lanyard switch OFF
Shift position switch ON
Oil press switch ON
Dual engine system switch OFF


next reading was when I first cranked it up


Save date March 31 2011
ECM No.: 68V8591A11


Engine Monitor
Monitor Item Result Unit
Engine speed 1081 r/min
Intake pressure 49.74 kPa
Intake pressure 14.76 inHg
Atmospheric pressure 990.9 hPa
Atmospheric pressure 29.3 inHg
Ignition timing BTDC 2 deg
Battery voltage (12-16) 13.9 V
TPS voltage (0.5-4.5) 0.743 V
Throttle valve opening (0-90) 1 deg
ISC valve opening 50 %
Fuel injection duration 2.4 ms
Water temperature (below 90) 25.9 °C
Water temperature (below 194) 78.5 °F
Intake temperature (below 70) 18 °C
Intake temperature (below 158) 64.4 °F
Engine stop lanyard switch OFF
Shift position switch ON
Oil press switch OFF
Dual engine system switch OFF

the ISC valve never reads %100 even with engine not running. from %30-50%, while running and %65 when shut off.
here is the youtube link to my ISC shut down rattle, you will notice that the motor takes about 15 secs to shut off after key is switched off, this seems to be consistent now, it use to take much longer sometimes.
http://www.youtube.com/watch?v=RKGDf7zgP80

[Sparkieboat]

Ok took boat out for a test run today...ran out great. After the TPS adjustment and the ISC valve soaking and the VST cleaning..the motor now runs great. The motor did stall out once when it was still cold, just after I got out of the no wake zone, and did skip a couple of times when powering up the first time...after that no stalls at all and no skipping at all in any RPM range..ran like a new motor. All power is back and then some. Prop is too small and it hit 6K RPMs @35 MPH with some throttle still left. Runs so good I almost want to keep it now. If it were the right shaft size i probably would.
I want to thank Rodbolt, 99, and boatmangc, for all of your valuable help. You guys are the best. If you are ever passing Savannah GA..PM me and I will buy you a steak lunch, or seafood.

[99yam40]

Good to hear it ran ok.
Did you find a problem with the thermostats and did you do anything on readjusting?

Did you ever find out if you have low 5V reference voltage?