2003 F115 Yamaha

[jay00f4]

I recently got it back from service for bad gas. They cleaned all the injectors and the vapor tank. The shop is now out of business so I am hoping to get some help here.

Went out Sunday and it the boat idles fine but wouldn't turn up more then 1600 RPM's under load. I checked the brand new water fuel sepreator and the fuel filter cannister on the back of the motor. All the fuel was good and clean. I then pressed the valve on the top of the fuel rail to see if there was pressure or air. I did that several times and now it will turn up to 4000 rpms under load and run perfect in nuetral.

Could this be the fuel pressure regulator or the mechanical fuel pump?

Thanks in advance

 

[Casco Bay Outrage]

Re: 2003 F115 Yamaha

They probably did not bleed the rail???

What is WOT and does she get there? If not what are the symptoms?

If the shop that did the work is out of business, I would bring the boat to a certified Yamaha mechanic.

 

[sunbird 18]

Re: 2003 F115 Yamaha

Fuel rails are self bleeding. The only way to tell what is going on is to put a gauge on the fuel rail and check the pressure. You can get a gauge at Harbor Freight or a similar place.

 

[jay00f4]

Re: 2003 F115 Yamaha

I went ahead and bought a new diapraghm for the mechanical pump. I will put that in and then test pressure on the rail. Does anyone know how much pressure it should have?

 

[rodbolt]

Re: 2003 F115 Yamaha

all the mechanical pump does is supply fuel to the VST, your going to find either a clogged VST filter or a stopped up injector.
dont rev it in nuetral cause its simply useless and not a good idea.
that motor MUST be capeable of 5800-6000 RPM at wot with its normal load or bad things normally happen.
rail pressure should be steady at about 35 PSI.
the injectors can be sent out to a place like flagship marine for testing and injector filter replacement.

 

[jay00f4]

Re: 2003 F115 Yamaha

The vapor tank, vst filter and injectors all just got back from being cleaned. This is the first time trying to use the boat after having all that work done and draining the tank to start over with fresh fuel.

Any other options?

 

[rodbolt]

Re: 2003 F115 Yamaha

nope
your describing the classic symptoms of either a VST restriction or an injector screen restriction.
I really dont care if all were clean this morning, if trash/debris was still in the system and gets into the VST or an injector screen at lunch you will have it apart again at dinner.
you can test fuel system vacum at the mechanical pump inlet, low pressure fuel at the pump outlet and rail pressure.
if all are good hunt for injectors.
since the introduction of E10 in our area fuel issues are a nightmare.

 

[Casco Bay Outrage]

Re: 2003 F115 Yamaha

Jay -

Rodbolt is a certified master Yamaha mechanic. Your getting the best advice there is.

 

[rodbolt]

Re: 2003 F115 Yamaha

dunno about the best.
yes yamaha gave me a shirt and a hat that look pretty cool.
I do this for a living and have done so for about 30 years, maybe a tad longer.
all I can do is tell someone what I think based on the symptom description I see on my monitor.
dang, I just looked at my post count.
I gotta get a life.

 

[jay00f4]

Re: 2003 F115 Yamaha

I appreciate the help and I am not doubting what he says. It just pisses me off that the solution he is providing is exactly what I just paid $600 to fix. It was a local Yamaha dealer with a Master Technician. That place has fallen a victim of the economy and are out of business.

Then first time in the water trying to get to RPM I have this issue. So I was hoping it was something different or something they didn't do like bleed the fuel rail or something. I am not excited about taking it somewhere else for another $600 bill.

 

[rodbolt]

Re: 2003 F115 Yamaha

its not hard and doesnt require much in the way of special tooling.
remove the intake manifold assy with the VST attached and take it inside to open it up.
other than a fuel rail test guage,rentable at a lot of automotive stores the rest is basic hand tools.
takes about 2 hours to clean the VST on the F115.
if the intake gasket isnt bent or damaged it can be reused.

 

[jay00f4]

Re: 2003 F115 Yamaha

Did this over the weekend. The VST tank was nasty and full of a rust like powder. Put it all together and it ran worse. Decided to pull the fuel rail and clean the injectors. Soaked the injectors in a Quicksilver Carb and choke cleaner for a couple hours. Put them back in took the boat out and it ran better then ever.

Thanks for all the help.