Help - f60tlr stalling infrequently

[DGEXPLORATION]

Hello,

Wondering if anyone out there had any suggestions to try and remedy my engine problem?
I have a 2006 Yamaha F60 TLR motor that I use highly on my bass boat down near Houston Texas.
For the past year, I have been having trouble with the engine stalling infrequently during a day of fishing. Some days it works fine, others it will stall out. I took it into the repair shop twice, and their diagnosis was "probably gum or residue clogging up the jets". Maybe so, but all of the treatments I have run through have not solved the problem. Last time I took it in they cleaned out the fuel system and ran powertune thru the VST, and it ran for 3 hrs. without stalling out, so they didn't replicate my problem.
I have always either bought Biobore EB (ethanol buster and other additives), or added Stabil (blue) to non treated gas. Recently I have also tried Mercury Quickcare, and last two trips some STP. Still stalling out on me. I have also replaced the hoses, and primer ball from the fuel tank, and added a water separator filter. In addition, I have ran the motor on a few trips with an external tank and a third new hose and primer ball to to the motor, and I still get the occasional stalling.
Now here is a synopsis of what happens when the engine stalls. I can cold start the motor every time, and idle away from the marina (2 minutes at idle), go full throttle to 5200 rpm, and run like hell... no problem. I can run around the lake at high speed from spot to spot and don't seem to have a problem. Now, if I decide to idle for a while, 5 minutes or more, the engine may die at idle, or it will die out when I try to throttle up after idling. If I just want to see it die, I can let it sit at idle in Neutral and after about 15-45 minutes, it will die out.
After the motor dies, I have two options, one I can have someone pump the primer ball when I am trying to start the motor, and it will start. I also need them to prime it a few times when I am throttling up to plane, and then it will run fine. Otherwise, I can wait a half hour or more, and it will start again cold. Immediately after it stalls, priming the ball without turning the starter accomplishes nothing. I must be cranking on the engine.
In my very uneducated opinion about this, it seems that priming the ball while cranking and throttling up supplies the extra fuel pressure that has been lost while idling. I have my suspicions about residue or something clogging the fuel system, as it cold starts and runs fine every time. One would think, it should still be "gummed up", if that were the case. For some reason, it seems the idling process is eventually starving the engine of fuel, and I really don't know why that would be. I hate to take it in to the repair shop a third time, and add to the $500 in labor I have already been charged, so I am throwing this out there to see if anyone has any good ideas as to what could be the problem.
Thanks very much if you see a solution worth sharing.

Regards,

DG

[99yam40]

check to see if it has a fuel cooler,
then make sure there is proper cooling water flow threw that cooler while idling

[rodbolt17]

that engine does have a fuel cooler.
if it does not work the fuel will overheat and boil with extended low speed operation.

OR
you have a weak fuel pump or an airleak on the suction side and it allows the VST to simply run out of gas.

[DGEXPLORATION]

Yes - I can check the fuel cooler.
I have my suspicions about the fuel pump, although the repair shop said it pressure tested good the first time I took it in.

Thanks guys

[rodbolt17]

remember that engine has two fuel pumps.
one is a low pressure lift pump that simply keeps the VST full .
the other is the high pressure pump in the VST.
if by refilling the VST manually works then the lift pump,or an air leak, is suspect.

[DGEXPLORATION]

I think you guys might be onto something with the cooler, because my initial complaint was it seems the engine dies when it gets "hot"....For example, my typical fishing routine of running and idling spot to spot did not result in a stall on Friday when we were wearing jackets and overcast, but it did yesterday when we were getting sunburnt.
Forgive me for asking without doing some more research, but I assume that the water supply for the fuel cooler is provided by the suction from the water intake , and part of that water flow is directed through the fuel cooler(by some sort of diverter or pump?). Just by looking at the service manual it seems the cooler is likely a (aluminum?) housing of some sort that accepts that water in a chamber(s) that is adjacent to the fuel in another chamber, so it would be hard for the cooler itself to be bad (unless it cracks and leaks), but more likely the water flow is restricted somehow. So, if I take the water outflow hose off, and I see good flow at idle, and maybe higher throttle for comparison, then I can't suspect that any hoses, fittings, etc.. are clogged, or leaking....

[rodbolt17]

water supply is from the engine tell tale water.
look under the fwd stbd corner of the VST,undo the water line to the cooler blow air through it.

I am not leaning towards the cooler though. if by MANUALLY filling the VST(using the primer bulb) makes the issue go away I would suspect a lack of fuel in the VST.

[DGEXPLORATION]

fuel cooler was clogged, excellent diagnosis.
Thanks guys very much for your input

[kaliann1]

I just cured my F60 of this problem. Bump the idle speed up a little.

[99yam40]

I just cured my F60 of this problem. Bump the idle speed up a little.

his motor was fixed years back from what he wrote.
why would you come along now and tell him to jack with the idle speed on an injected motor.
that is not the right answer to anything.
fix it right or find someone that can