2003 F200XTRB Low fuel pressure / stalling

[AS350Pilot]

Good afternoon,

I have a 2003 F200TXRB that I purchased approximately 2 months ago with about 638 hrs on it. The engine runs and sounds great at speed; however at lower rpms it sometimes stalls, or tries to. Usually my son can pump the primer ball and it will come to life, so I seems to be a fuel supply issue to me. It will also do it after it has warmed up when I first apply power at or near full power as I attempt to get on plane. Unfortunately, or fortunately (how every you want to look at it) it only does it once in a while. It will stay running if the primer is pumped, and will stall if we can't get to it fast enough.

Can someone point me in the right direction? I see Yamaha fuel pump assemblies are priced wildly at almost $600 so I hope it's not that...

Thank you in advance.

[fairdeal]

[QUOTE=AS350Pilot;105506]Good afternoon,

I have a 2003 F200XTRB ...The engine runs and sounds great at speed; however at lower rpms it sometimes stalls, or tries to. Usually my son can pump the primer ball and it will come to life,

Sounds like a faulty check valve aka "relief valve assy" - a mere $135

It will also do it after it has warmed up when I first apply power at or near full power as I attempt to get on plane.

But I don't know the check valve can cause that.

Well, actual knowledgeable folks should be along shortly to help....

[bajakeith]

running issue

Its late and I not gonna look up your motor right now..check and or just replace your lift pumps and a GOOD new fuel line w/primer complete from Yamaha or serria is a GREAT way to keep these motors running for the season..always give all (4) ends a light shot of oil when installing fuel line...

[rodbolt17]

one more time, this outta be a sticky.

the F200/225 lift pump runs 10 sec on 20 sec off below 1200 RPM.

over time crud/corrosion will cause the relief valve to fail.
this valve is inline between the VST inlet and the lift pump inlet.

its designed to maintain about 10 PSI on the vst inlet,once the VST needle closes excess fuel is simply routed back to the pump intake.

if that valve leaks it wont maintain pressure on the VST inlet and everytime it cycles off more and more air collects in the VST to pump inlet line.
as the fuel aerates when going back through the pump intake it quits pumping fuel and the VST gets low,low enough and the engine quits.
if marginally low and you whack the throttle the injectors immediately go to not only a synchronous fireing but group injection all the while the sense line on the regulators adds abot 5 PSI on the rail.

suddenly finishing off the remaining fuel in the VST.

two easy ways to check.
1 simply watch the fuel in the fuel cup,you will see it go up and down about 10 sec on 20 sec off when idleing.

or use a pair of needle nose and pinch the line between the valve outlet and the pump inlet.
yep, its just about that simple.

[AS350Pilot]

So in summary, this Yamaha 69J-24460-00-00 RELIEF VALVE ASSY is what I need after I verify based on your instructions?

Also since I could be replacing this item is there anything else I should replace at the same time? I was thinking of replacing the fuel filter as well.

[fairdeal]

So in summary, this Yamaha 69J-24460-00-00 RELIEF VALVE ASSY is what I need after I verify based on your instructions?

Also since I could be replacing this item is there anything else I should replace at the same time? I was thinking of replacing the fuel filter as well.

Yes, the part at issue is 69J-24460.

Sure, "while you're there" - it might be prudent to replace "the F-filter"
69J-24501

[AS350Pilot]

Thank you all, I greatly appreciate the assistance.