Rough idle....running out of gas in neutral.....Yamaha OX66 EFI...HELP!!!!

[MWeb]

I just changed out the low pressure fuel pumps 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.

Can this be just be a bad fuel Bulb? Vst Filter? Fuel Lines from the tanks??


Any helps would be really appreciated!!

[Stratos21XL]

Two things to try but it will require you to take some along if you go to the lake to test. Have someone pump the bulb while you are running the boat, the other thing is if you haven't already tried it is get another tank with known good fuel and hook it to the motor and see what happens. If it runs fine then it's in the boat (fuel or fuel delivery) if it still runs like crap then its something in the motor itself.

Keep us posted please.

[MWeb]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by Stratos21XL &raquo;</td></tr><tr><td class="quote">Two things to try but it will require you to take some along if you go to the lake to test. Have someone pump the bulb while you are running the boat, the other thing is if you haven't already tried it is get another tank with known good fuel and hook it to the motor and see what happens. If it runs fine then it's in the boat (fuel or fuel delivery) if it still runs like crap then its something in the motor itself.

Keep us posted please.</td></tr></table>

The fuel in the boat is good. Just filled up the other day with startron and ring free. So I am thinking it is either the bulb, fuel lines and or the VST filter.

I am gonna check out the fuel water seperator too and empty it.

[Stratos21XL]

that is the point in using an external tank, it takes all of that out of the equation. If you try the external tank and the motor idles properly then it would be one the things you mentioned like fuel lines, bulb, or the fuel/water separator. If it still runs bad using the external tank then it could be the VST filter or in the fuel delivery system on the motor itself.

Are you using 100% gas or ethanol blend and has the boat been sitting for a while without being used?

[MWeb]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by Stratos21XL &raquo;</td></tr><tr><td class="quote">that is the point in using an external tank, it takes all of that out of the equation. If you try the external tank and the motor idles properly then it would be one the things you mentioned like fuel lines, bulb, or the fuel/water separator. If it still runs bad using the external tank then it could be the VST filter or in the fuel delivery system on the motor itself.

Are you using 100% gas or ethanol blend and has the boat been sitting for a while without being used?</td></tr></table>

Its not the gas, it has happened with every fill......

[MWeb]

Anyone else? I changed the low pressure fuel pumps, bulb, vst filter.......

I am leaning towards the injectors.....?

[MWeb]

Are there Yamaha Techs on this site?

[SkeeterJohn]

Is this only at idle? and how long from startup will it run before it cuts out?

[MWeb]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by SkeeterJohn &raquo;</td></tr><tr><td class="quote">Is this only at idle? and how long from startup will it run before it cuts out?

</td></tr></table>

Only at idle. And it cuts off rarely but usually when it starts running rough I will put some load on and depress the hotfoot a little. After I go for a run it wont do it.

[MWeb]

up.......

[SkeeterJohn]

ok a stupid question but when did you change your plugs and are you 100% sure they're gapped correctly.

[MWeb]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by SkeeterJohn &raquo;</td></tr><tr><td class="quote">ok a stupid question but when did you change your plugs and are you 100% sure they're gapped correctly.

</td></tr></table>

Checked that, that is all proper......

[MWeb]

Anyone else?

[Rich Z]

I’m not saying that this the way it should be but that is very typical of engine “loading up”. Excess fuel puddles up in front of the reeds. Why not just adjusting the idle screw a little and bring up the rpm. Injectors may need cleaning or tps adjustment.

[MWeb]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by Rich Z &raquo;</td></tr><tr><td class="quote">I’m not saying that this the way it should be but that is very typical of engine “loading up”. Excess fuel puddles up in front of the reeds. Why not just adjusting the idle screw a little and bring up the rpm. Injectors may need cleaning or tps adjustment. </td></tr></table>'

I am doing the VST filter tomorrow and cleaning of the injectors then I have a tournament on Saturday and will report back then how everything ran.....

I swapped out the fuel water seperator filter today also for shit and giggles.....there was a tiny bit of water and debris in the fluid. Not sure when the past owner changed that filter last but I did that today also.

[MWeb]

So I finally get the boat out after everything was done. And apon startup and throughout the day everything was amazing and felt like a new engine.

Then towards the end of the day I bump a mud/silt pile and then 5 minutes later the problem comes back......i dont understand anymore......anyone?

[Rich Z]

Behind the ecu there is a exhaust water jacket plate with 25 10mm bolts. Remove and unplug the ecu and hook up a water hose to the flusher. Turn on the water and inspect that there is no water coming out from around these bolts. Had a similar problem where one of these bolts rusted out and water was spraying on connections of the ecu causing a very bad idle and sometimes a miss at wot.
Have you had the injectors cleanned and flow tested?

[MWeb]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by Rich Z &raquo;</td></tr><tr><td class="quote">Behind the ecu there is a exhaust water jacket plate with 25 10mm bolts. Remove and unplug the ecu and hook up a water hose to the flusher. Turn on the water and inspect that there is no water coming out from around these bolts. Had a similar problem where one of these bolts rusted out and water was spraying on connections of the ecu causing a very bad idle and sometimes a miss at wot.
Have you had the injectors cleanned and flow tested?


</td></tr></table>

Injectors are the next step this week.......