2003 Yamaha F115TLRB Won't Reach Max RPM

huntnfishguy

Cadet
Joined
Aug 10, 2014
Messages
8
I will try to keep this as short as possible. Issue started about month ago. I have checked the gas and no water. Added Sea Foam just to be safe. I have always ran ethanol free gas for last 4 years. Changed the plugs and fuel filter. Checked the screen on fuel pickup tube. Motor had a intermittingly miss at idle but always started right up and trolled all day at about 600 rpm. What it does when you put the hammer down it jumps to 2500 rpms and then as you trim it up it slowly climbs to 4500 rpms with just myself in the boat. Add a 2nd person and I can only get to around 3500 rpms. Use to top out around 5800 rpms. Had it at local repair shop Coil to #2 & #3 cyl was weak and intermittingly. They changed coil and checked the electrical components. Good spark. All OK. They tested the cyl compression. 120# or better on all 4. 45 # of fuel pressure at the injectors. Everything seems fine except on top end. Motor runs smooth. Local shop has no dino equipment that could read any error codes. He feels stumped. Before I take it to a shop that does have the equipment was looking for any suggestions on anything else to try. Its a ways down the road to nearest Yamaha dealer.
 

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
8,851
120 does not sound high enough for a 4 stroke, but a leak down test would be better test
Injectors and timing would be a good thing to look at
 

Capt Ken

Commander
Joined
Jul 30, 2002
Messages
2,269
The number on the compression doesn't bother me if they were all pretty even. Compression gauges aren't created equal but taking an engine to a shop without the proper equipment is a waste of time and money. I would start with the VST filter then the injector filters. But the shop needs to know how to change the injector filters being not many shops do. Not something in the repair manuals.
 

huntnfishguy

Cadet
Joined
Aug 10, 2014
Messages
8
Thanks for the comments. I am not clear on the vst filter. It would seem that if I have 45# pressure at the injectors then the vst filter should be ok or am I thinking wrong. Either way I have made up my mind to bite the bullet and going to take rig to a yamaha dealer. Its nice to know that there's people like yourself out there willing to share your knowledge. Thanks again.
 

huntnfishguy

Cadet
Joined
Aug 10, 2014
Messages
8
Just got a call from the Yamaha Marine Shop after they ran a diagnostics test on the motor. They tell me that the injectors need to be re-tooled and need to be sent in for repair. I asked what would cause them to go bad and was told it was bad gas. They felt sure this would correct the problem, but would be about 2 weeks to get them back. My question is would the gas cause this to happen or are they just plugged. What would a re-tooling involve? What am I getting for the 500 - 600 total cost they are quoting me. Now I understand that also includes the labor and diagnostic costs. But when I add the 275 from the first shop for a coil and labor this is getting to be an expensive fix. I also will throw out another question. I do a tremendous amount of trolling with that motor. I would guess in the range of 100 to 125 hours per year, all of it at the idle speed of 600 rpms. Would this have any bearing on the injectors. Would I be better to add a kicker to the boat for trolling.
 

pmassey31545

Seaman
Joined
Jun 11, 2005
Messages
52
Not sure I can help much with the problems you are having, but I will tell you this.......I just bought a 60HP Yammi 4 stroke and the first thing I did was buy the diagnostic software and cable. Got mine for $75 on eBay. Just search for 'yamaha diagnostic' and make sure your year and model are listed.

Again, not sure it would help with your issue, but may help you in the future and other issues. It can tell you what the engine computer says the RPM's are. I had a similar issue with my RPM's showing low and it was the gauge...engine and software showed the actual. The software can tell you the total hours and also the number of hours spent at each RPM interval. For example: 0-1000, 1000-2000, and so on. Very handy. You can test injectors, fuel pump, spark/fire and more. Well worth the money.

Sorry I couldn't be more help, but get the software. You will love it. And if you get it, message me if ya need help man. Good luck with your motor.
 
Last edited:

soflayami

Recruit
Joined
Aug 20, 2014
Messages
1
I'm no expert but researching the forums I have found several posts that suggest that your problem could be injectors(dirty),IAC valve or TPS.
That being said I think you;re correct in assuming there's no problem with the HP fuel pump/filter since you have 45 lbs. pressure. I just sent my
injectors to professionally cleaned in So.Florida and the cost was $110.00 which included changing filters and o-rings. I'm not sure what re-tooling
means as far as what your mechanic is telling you. Either way good luck, hope some of this helps and please update us on the outcome.
 
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