PROBLEM- 2004 Yamaha 150hp OX66- idle shake and shutdown

[Bassaddicition]

I just changed out the low pressure fuel pumps, fuel bulb and VST filter on my Yamaha 150hp OX66 Efi....and I am still having the same symptoms.
In neutral while idling or in forward and no pressure on the foot pedal the engine is giving out as if it isnt getting enough fuel and will sometimes stop running and cuts out.

I tried to self diagnose the issue then spoke with my friend and boat mechanic and said the problem would show its face at higher speeds if one of those parts were faulty.

I did the first two replacements with no luck, then did the VST filter and took the boat out on Saturday morning and it started and idled amazing!! thought I had a new motor but it was 40 degrees that morning and abnormally cold. So I think it was the cold weather and not the change of the VST filter.

I wound up fishing a lake where I didnt even really need to run the motor to get around, I ran it once in the morning time and it went well, but it seems once the motor is warmed up and I start it then the shaking of the motor starts and then once in a blue moon it will completely cut out ONLY at idle or in forward with no load on the engine. I hit a mound of mud/silt with the motor and after that, thats when the same issue came back with the motor this day, not sure if hitting the mound sucked something into something? or it was just because it was the second time and it was mid day and hot and the motor had finally warmed up to show the problem again.

So I am starting to think its the injectors? My friend just texted me we are going to drain the tanks, not sure why and never heard back from him. But I have filled up 15 times in the past month or so and it is consistent.

[Tucker]

What'd the filter look like on the bottom of the fuel pump? Any crap in the bottom of the VST. If you had crap there chances are you have it in the injector screens. There are injector guys in Florida and another one in the North East. I think the charge is about $22 per injector. I'm living dirty fuel now and feel your pain...

[Bassaddicition]

What'd the filter look like on the bottom of the fuel pump? Any crap in the bottom of the VST. If you had crap there chances are you have it in the injector screens. There are injector guys in Florida and another one in the North East. I think the charge is about $22 per injector. I'm living dirty fuel now and feel your pain...

The low pressure fuel pumps I didnt look at, I just popped them off and put in the new ones cause I was in a rush to get out on the lake.

The VST filter was fine. My friend said that there was a chance that the VST had air in the line at some point or possibly water.

There was a little water/dirty substance that was in the bottom of my fuel water seperator filter that I replaced that the same day which I didnt list above, but not enough to get worked up over.

My friend and I are gonna drain the tanks, not sure what else he wants to do, he didnt go into detail about it. I think he may try to clean the injectors somehow with a cleaner. If needs be I will get the injectors rebuilt, I spoke to a tech at the local yamaha dealer/service center and mentioned that the place in Florida can do it for me like u said.

[Bassaddicition]

Also the last owner always used Ring Free which was stated by the manual, but NEVER used ethanol treatment because it was supposedly not stated in the manual, could this be one of the reasons why I am having these issues with the fueling?

[Bassaddicition]

Bump for morning answers and suggestions......

[rodbolt17]

myself I would simply monitor fuel rail pressure.
quick easy and eliminates a lot of stuff quickly.
if you suspect injectors the filters are easily removed.
each injector has a filter.
Yamaha does not offer the filter but the 98-2000 mercruiser MPI 7.4L has them for about 3.50 a piece.

[Bassaddicition]

myself I would simply monitor fuel rail pressure.
quick easy and eliminates a lot of stuff quickly.
if you suspect injectors the filters are easily removed.
each injector has a filter.
Yamaha does not offer the filter but the 98-2000 mercruiser MPI 7.4L has them for about 3.50 a piece.

So instead of getting them rebuilt I could just swap the filter in them I am assuming, correct (just double checking)?

Personally I wouldnt know how to monitor the fuel rail pressure but my friend would, I can replace bolt on parts like pumps, bulb, filters....etc. I guess I will learn something new this week. Thanks for the response.

[Bassaddicition]

Do you know a name of a company that does the Injector rebuilds in the northeast? I know there is one in florida and I forget their name. Let me know, thanks.

[Tucker]

Think I read about it on THT. Might want to check there.

[jb123]

first things first, monitor rail pressure

[rodbolt17]

flagship marine in punta gorda FL gets all our injectors.

[Bassaddicition]

Injector-Rehab Fuel Injector Cleaning Services

Here is the place I am looking at. I emailed them and they say they do Yamaha injectors daily and its only 21 dollars an injector.

Flagship marine engine is the place the local Yamaha dealer said they send theres, but wouldnt the service be the same at any reputiable Injector repair place??

[Bassaddicition]

How hard is it to remove the injectors? Anyone have a do it yourself online somewhere?? I am tired of waiting on my friend and I am pretty good with my hands and tools......

[Bassaddicition]

Could the O2 sensor be the route of this cause by chance too??

[rodbolt17]

takes about 10 min to remove the OX66 injectors.
you will remove the airbox, scratch your head on removing the wire clips that hold the connectors to the injectors.
once the connectors are removed remove the 10mm hex head bolts holding the rail to the air valve assy.
then remove the injectors.