2003 F115 stalling/skipping and would not shut off once

[Sparkieboat]

99 you are right, the kill switch should have still worked even if the key switch was messed up. so maybe I do still have an issue with that. Rod said I need to make sure that key switch is grounding white wire and that there is no voltage on the yellow wire..I will test tomorrow..I am really feeling intimidated about removing the intake manifold is why I haven't already cleaned the VST..guess I should just do it and rule out the VST filter. Thanks again for both of your very valuable help, I really do appreciate you taking time to help me out with this. I will post my progress.

[99yam40]

Sorry I miss read and stated your post Rodbolt about the filter.
What do you think about the kill switch not killing the motor?
So do you think the filter is his main problem? It seems that if he gets it past the off idle RPM fast enough it will run at higher RPM without a problem, but I have no idea if it will in the water loaded.
And like you said it is a maintenance item that needs to be done anyway

Sparkie
I see you where posting same time as I was, so let me add That is with the key in the off position that the white is suppose to be grounded and the yellow drops the 12 V

[Sparkieboat]

yes i will go ahead and order the gaskets needed for a VST cleaning...

motor does same thing out on the water under a load..I can rev it up to about half throttle fast and it will take off..but it will have some intermittent skipping/misses until about 7/8 throttle. from 7/8 throttle to WOT it will NOT miss or skip at all, not even once. the skipping/missing decreases when the motor is warmed up, and it does not shut off when I go from idle slowly up as much either after warmed up.

I may make another video after I clean the VST and do a wire check, if it is still doing it. I hope the video helped.

Rgr on the key switch being in the off postion for wire test...
gaskets ordered..I ordered a intake manifold gasket and the VST cover seal.

[Sparkieboat]

ok I put the key switch and kill switch through a tough series of test..they both passed without any flaw..the key switch powered up the yellow wire and ungrounded the white wire when turned on every time, then grounded the white wire and stopped 12v on yellow wire when turned off, even with wiggling I could not get it to fail even for a split second. the kill switch also passed multiple test and opens and closes the circuit like it should every time. so maybe the ECU is acting up. any way to test it?? Is it possible that the ECU could be the culprit for the skipping/stalling issue?? I know Rod seemed pretty sure it was a fuel issue.

By the way..I do not know if it means anything but the alarm does not give the beep (I did test alarm, tested ok) when you turn the key on like it does with my other boats. maybe it is not supposed to, I do not know.

I have the gaskets on the way and will go ahead and clean the VST out good, I will let you know the results. Thanks again for all of your help.
Sparkie

[Sparkieboat]

VST cleaned

ok..I got it all apart..sure do wish it had a 2 piece bottom..2 of the bolts were kinda hard to get out. who ever the genius was that put phillips screws holding the VST together needs to be shot..almost stripped out 2 of them..I am headed to store now to get allen head screws to replace them all with. here is a pic of the VST filter before cleaning. waiting on mail lady to bring new VST seal and intake gasket..

[rodbolt17]

and ya really really wonder why it runs like crappola?
your not big on maint are ya?
VST filter cleaning needs to be done once a year, yes its a pain but never the less its gotta be done.
you may look into adding a 10 micron pre filter between the fuel pump and VST inlet. the 07 and later engines had this.
as nasty as that filter is I would remove the injectors,flush the lines and the rail and spray out the injector screens as well.
also are you running a 10 micron water seperator in the hull?
usually if not bent ill reuse the intake gasket.
that engine will actually run with rail pressures as low as about 25 PSI, however it runs nasty.
need about 45 PSI at ALL rpm and load to run correctly.

[Sparkieboat]

fuel pressure on the rail was holding around 36, if I remember right..and I just purchased this boat 4 weeks ago from a guy in Myrtle Beach and no he was not a maintenance type person, I have been repairing all kinds of little things on this boat since I got it, including toggle switches and several of the little breakers that goes under them, a fuel tank sending unit as well as motor stuff like fresh oil and filter and gear oil, spark plugs. The 24v rip tide *****ing motor needed both boards replaced, he was running it on just one 12v battery..and here is a kicker, The motor is a 25" shaft on a 20" transom, I did not even think to check for that when I picked up the boat, I assumed it was a factory set-up, So I got it on a manual jack plate jacked all the way up and still could go up 2 more inches..so I may sell this one anyway and buy a 20" shaft and a hydrolic jack plate and a set of trim tabs.
and yes a yamaha high performance 10 micron filter (a big one) is in the hull and yes I just replaced it, there is a fuel filter also under the cowl where the fuel line comes into from the bulb..but not one between the fuel pump and the VST..

have you got a part number for that filter?? I will buy one immediately and install it.

since the VST cleaning it does seem to be running better, I will know after a river test tomorrow.

[rodbolt17]

the one from yamaha is about 70 dollars.
run to napa and buy the marine rated under hood inline fuel filter with 5/16ths nipples.
cut it in.
sounds like you may have a good time straightening out the previous flying monky's issues.
long before I blamed any ECU issues I would correct and catch up on maint issues.

[Sparkieboat]

I will...He said he had it serviced back in 2008..I am not sure what that means but the timing belt looks to be in good shape, and I will do the water impeller soon..I have already done oil and gear oil and all new filter new plugs, i will pick up a inline filter tomorrow, I have used the glass one from NAPA before they are good filters.....anything else that I should do to it???

by the way..my tach was acting funny today..it quit working for a little while then went to working, then bounced around for a few secs, then went to working perfectly....

[rodbolt17]

glass in line filters are NOT USCG approved under the hood.
ONLY use USCG approved stuff.

[Sparkieboat]

ok on the no glass filter thingy...

I took it to the river today..I now have smoother acceleration..but seem to have lost some HP somewhere..motor is boggy and doesnt have the jump it had..wound out to around 5700 RPMs ..it was going just over 6K..I know I need to reprop and keep the RPMs below 5800..but thats another issue.

engine also made a metalic knock sound several times at WOT..never did this before, could have been like a spark knock only happened at WOT and trimming up past 5500 RPMs..fuel pressure only came up maybe 2 psi after VST cleaning and is holding around 39 pretty steady at all RPMs..I am going to take to a dealer Monday or Tuesday, and get a computer diagnostic. I am pretty sure the ECU is messing up..after shutting engine down, which took several minuets because it is still not shutting off like it should..some times it works perfect then other times it does not..I restarted engine and it seemed a little more peppy and did not make the clank noise again..but i did not run it much more..just took it out and will get a diagnostic before running it again.

Tach is also freaking out..it comes and goes and sometimes just jumps around while engine is idling smooth. engine cranks and idles perfectly.

I am going to try Custom Marine in Statesboro GA..they are supposed to have a master Mechanic..they are about 25 mins from my house.

[99yam40]

Good luck at the Yamaha place hope they can find something, metallic noises are never good.

I wonder if your pressure gauge is off some, as Rodbolt said it should be around 45

Looks like you were the the last one to post 2 days ago, so like you said you may have been the one who broke it.

But I am glad to see it back up and running again

[Sparkieboat]

glad they fixed it...just send me the bill, every one else does...LOL
Still waiting to hear from dealer. the metallic sound was disturbing,..but It was the first time I have heard anything like it and I am thinking it was some type of spark knock it did it several times on my first run. It did not do it again. I am sure that something has started messing up with the motor since the last time I ran it..because the ECU seems to be acting batty with the no shut off thing and the RPM gauge thing. So I am hoping for a report today. It is possible that my fuel pressure gauge is wrong, it is a cheapo, but it is new. possibly some other clog issue, Rod said that he would have done a thorough flush of the entire fuel system including the injectors..I will wait and see how it does after I get the electronics fixed.

[Sparkieboat]

I wanted to update this thread. I had to go get my boat back from a local yamaha dealership, after 2 weeks and a string of broken promises, I have absolutely no confidence in anything they tell me. I just choose not to deal with someone I can not trust.

I took the fuel rail off and flushed it, although it looked clean. I also sprayed out the injector screens, if that means to spray carb cleaner into the back of the injectors while holding them upside down. I also sprayed carb cleaner into the fuel pressure regulator.

I will need to replace the red orings because all of them were damaged. I will use this as a good reason to go check out the next Yamaha service center..If anyone knows a good one near Savannah GA please let me know.

also I will mention that the motor seems to have some skipping issues now...it seems to come and go..for instance I was testing the boat a few weeks ago and it was not running right then I shut the motor down which took a minuet, then it started running pretty good.

[99yam40]

Sorry if I sounded harsh about not putting your info in your thread instead of his, but the info will be lost to someone that is looking at yours and confusing when multiple motors and problems are being talked about in a thread.

You may want to test your pressure gauge to make sure it is reading correctly and think about sending the injectors off to have them serviced, as they should give you a readout on as found and as left to make sure all that is good and if there was a problem with them to start with. They will collect trash just like the filter you found.
I wounder if the pump has a internal filter in it also, or was that just the HPDI motors.
any way you need to find out why you are not reading 45psi as Rod mentioned