2003 F115 stalling/skipping and would not shut off once

[Sparkieboat]

I have a 2003 F115 fuel injected four stroke. My motor starts and idles perfectly, but will shut off or stutter when you go to throttle up even when not under a load. it gets better after it gets warmed up but still wants to skip some until about 7/8 throttle. then it smooths out completely. Even after being warmed up good it will skip causing the motor to jump intermittently at mid range throttle up to about 5200 RPM. I have new plugs and have tested fuel pressure I have around 46 psi when I turn the switch on and 38 psi when running. I did notice that fuel pressure spikes up about 8 psi when engine tries to stall. Engine usually takes about 2 secs to shut off after I turn key off, yesterday engine would not shut off, even after I pulled the kill switch. After about 2 mins it finally sputtered to a stop. after that it cranked with the kill switch out and then sputtered to a stop after about 8-10 secs. I let it set for a few mins and it started working fine again. I tested key switch and kill switch both seem ok..ground wire in harness OHMed out ok. I am starting to suspect my ECM..is there any way to test it without taking it to a dealer?? If I do take it to a dealer will it have trouble codes stored that will indicate my problem?? I think the stalling and the no shut off problems are coming from the same place, but I could be wrong. compression is 160 psi and appears to be good spark on all cylinders.
Thanks Sparkie

[99yam40]

I forgot to tell you Rodbolt17 said he was going to a training thing for a week or more so hang in there and maybe he will log on in the evenings or maybe not till he gets home.
But there are others here that may help

[Sparkieboat]

here is an update..engine now takes about 1 minuet to shut off after turning key to off position..and will crank with kill switch pulled but will run rough and then sputter off after about 10-15 secs. when I turn the key switch off engine does not skip or sputter but turns off normally after about 1 min. and thanks for all of your help 99

[99yam40]

I see Rodbolt posted some this morning, but did not get to yours. I PM ed him to look at this thread

[Sparkieboat]

thanks a lot 99..and good morning, I hope you have a great day. I have to go get some paintball supplies for our Church Youth event this weekend. I will be back this afternoon.

[99yam40]

I was thinking that paint palls would hurt in this cold weather, but with all the clothes and protection needed it is probably a lot better when it is cold, other wise they would be sweating too much.
Some of the not so bright paint baller's around here have been shooting cars,signs,houses, etc.
Light duty drive bys I guess.
I have some residue still on my garage door that did not come off when I scrubbed it a couple of years ago. I thought that they were made of stuff that would not hang around that long

[Sparkieboat]

yes they can hurt in the cold but we keep the paintballs heated until **** time and they stay pretty soft..and yes we pile on the clothing, so it works out. If you do not clean the paintball residue off pretty fast it can stain or be very hard to clean..i found this out the hard way...lol

[rodbolt17]

been busy.
but now we get to do some playing.
you have, most likly, multiple issues.
one is going to be fuel related.
the other expensive.
when the key is turned on the ECU wakes up and then starts the key on sequence to power up and look and various devices.
at key off the ECU gets the key off signal and starts the various shut down sequence.
if the main relay contacts stick you get your symptoms.
at key off start tapping the relay lightly with a screwdriver handle.
if it does not change.
do the same with the ECU.
when the ECU gets a stop signal it starts turning off IGN,FUEL,INJECTORS and then it resets the ISC valve for the next start cycle THEN shuts off the main relay.
ECU is kinda pricy.
check ALL connectors and pins on the ECU.

[Sparkieboat]

Thanks a lot for the reply Rod. I have done a fairly good check on the ECM connections, and ground wire..all ground connections are bright and tight. all connections seem good. I will do the "tap" test on the relay tomorrow. By fuel related, I assume this is addressing the stalling/skipping issue, It will stall out even when on the muffs and out of gear when I go to throttle up it will just shut off..it does get better after it gets warmed up but still stutters when taking off, but will clear up past 7/8 throttle. I was thinking of cleaning the screen on the bottom of the high pressure pump, but it looks like a big deal to get to. Do you think it would be worth the trouble??

[rodbolt17]

takes about 1.5 hours for me to clean/replace that VST screen
yes its a pain and yes the intake comes off the head.
its also a maint item.
but it wont affect engine shutdown.
thats typically a relay or ECU failure.

[Sparkieboat]

Yes I figured the VST filter may be my skipping/stalling issue?? This is my first fuel injected engine. maybe if i fix the relay/ECU problem all will be solved. I will do that first. If I do clean the VST what gaskets/seals should I replace and not reuse?

[Sparkieboat]

Ok I was testing the relays and found that my engine not shutting off problem is in my key switch..it tested out ok when I checked it but now if I wiggle it firmly into the off position engine will shut down..whew I thought I was looking at $1K ECU. I made a video of the stall maybe this will help. YouTube - 2003 Yamaha F115 stalling

[Sparkieboat]

Hey Rod and 99 did you get a chance to view the video?? and do you still think that the stalling/skipping is fuel related?? I noticed the other day when I removed my plugs that the #3 plug was wet, all others were dry and engine was cold and had not been run that day.I also meant to mention that when I turn the key to the on position the fuel pressure goes to around 46 PSI but drops pretty fast to below 40 and holds at around 38, but I havent check it for more than about 10 secs..maybe a bad injector?? I still have not cleaned the VST screen/filter. I will have to order some gaskets before I can. Thanks again for all of your valuable help. Sparkie

[99yam40]

I would monitor the fuel pressure while the problem is happening to see what it is doing.
You said it was spiking back to full 46 psi when it tries to stall?
As a wild guess ,I would think that for it to spike like that, it is loosing key on signal and then regaining it maybe putting full voltage back on the pump for a few seconds like on start up. Doen't know if it is loosing the pressure causing the stall or maybe high pressure flooding cylinders.
Rodbolt17 will have to way in on that.


It does not make sense that the kill switch would not shut down the motor even if the key switch had a problem. So you may still have some other issues.
Remember what Rodbolt17 said the filter will not cause the motor to stall out

[rodbolt17]

the filter CAN cause a stall.
it CANNOT cause a failure to shut off.
key words.
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.
if the key switch is failing to either ground thge white wire OR taking 12V off the yellow wire the ECU goes batty.
its looking for both at the same time to start the ECU shut down sequence.
the F115 takes about 10 seconds to power down the ECU after engine shut down, the F350 takes about 20 seconds.