06 F60TLR possible vapor lock ???

[Fred Pittman]

Yeah, seems that way to me too. Always thought fuel delivery, BUT Yamaha did put a fuel cooler on the engine for a reason, I even read that Merc used 2. If the engine is overheating then the fuel cooler loses it's ability to function properly??? Going to water test it Wed. I'll carry tools to remove the thermostat and carry infrared gun to take temps on the water. Thanks, Guys... Will let you know Fred

[Fred Pittman]

UPDATE: Took it to the lake today and all started off great. It fired right up (as always) and I headed out from the ramp. Dropped RPM's down to 900, took the cowling off and it ran like a champ for 2 hours...no stall, no sputter. I put cowling back on and headed down the lake running it at different speeds from 2000 to 5500 and it ran great. After maybe 15 to 20 minutes of cruising, I throttled back down to an idle, settled in at around 1000RPM's and ran great for maybe 20 minutes, then sputtered, RPM's dropped to 300 for a second or two, then it died. I used the infrared thermometer on the motor and it's NOT overheating. Fuel cooler never exceeded 128 degrees. Squeezed the primer bulb a few times and it fired right up and idled for maybe 5 minutes before it started stumbling again. A few pumps on the primer smoothed it out and it idled another ten minutes or so before it did a repeat. After the third stumble, it smoothed out and idled for maybe 30 minutes before I headed in. Now I know it's most likely NOT heat related.

[pstephens46]

I think your heat issues were the muffs. Use two hoses next time. Interested to see what the pros say about this.

[erniefish]

Thanks for the updates , although i Do not have that motor , one of my friends may have one, any learning on this forum is priceless , thanks ,good luck

[Fred Pittman]

Here's the whole story on the motor: ( maybe there is a hidden clue here somewhere)
I bought the motor last spring from the original owner. It was on a boat that he used to take his kids up the Biloxi river (salt, brackish) and he only ran it sparingly. He told me that it was routinely serviced by the Yammy dealer on the coast. He advertised the boat for sale and he hadn't cranked it in several years. ( I asked him about fuel additives or non-ethanol gas and he told me he just put pump gas in it.) A man came and bought it but couldn't get the motor to start so he returned the boat. That's when I came in and bought it for a reduced price. I brought it home and found no fuel pressure at the rail. I removed the vst and found a burned terminal on the fuel pump. I ( cheap guy I am) couldn't at the time afford a yammy pump so I ordered an aftermarket pump from Ebay. I cleaned the gunk out of the vst, installed the new pump, but I bent the float when reassembling the vst. I straightened it out , checked settings, installed it on the motor. New fuel line with primer, new gas tank, new filters,everything flushed out (fuel related). Put it on muffs, and cranked it right up. Ran like a new one so I put it on my pontoon boat. First trip out it ran great for maybe 15 minutes, then started to stall. Primed it up and restarted it, but after a few minutes it stalled again.
I'm thinking sticking needle and seat so I ordered a new one along with a new float. Since then I have installed a new OEM high pressure pump but the stalling issue continues. Sine the i've replaced the low pressure lift pump with new OEM. It only happens when motor has been running for awhile. It's exactly the same issue it's had all along. I never know when it's gonna start. Just a totally random thing.I have never been able to duplicate it either in a barrel or on muffs here in the yard. It's almost always when in gear just idling but once it happened as I left it in neutral at the ramp as I went to get my trailer. (that''s about it, guys....an't think of anything vital to add)
Thanks, Fred

[99yam40]

need to monitor fuel pressures to see what is going on. apparently the VST is running out of fuel if you have to pump the primer bulb to get fuel into it.

making sure the pumps are getting power when they should be may help also.
if pressure drops but you still have +&- to pumps should give good info

burnt terminal on HP pump may mean bad connection

[Fred Pittman]

My problem is that it never messes up in the yard, either on muffs ( i have dual muffs now) or in the barrel. The motor sits back on the pontoon boat and is not easily accessable on the water. As of now I plan on connecting a vacuum gauge to the inlet side of the lift pump and using a remote start button to jump the solenoid so motor will turn over and not start. I'll get a vac. reading there, but should I drain the fuel line on the pressure side of this pump and leave it disconnected to get vac. reading?
Next I'll install a tee into the pressure side of the line and crank the motor up and let it idle and check pressure there. Then I'll have to cut my high pressure fuel line between the vst and the rail and install my pressure gauge there to get a reading. ( my motor doesn't have a schrader valve to hook into to check pressure)
Then I guess I'll just have to let it run and HOPE that it eventually will stumble and die. Then I can drain the VST and measure the amount of fuel in the tank after checking the rail fuel pressure after it stalls.
Does all this sound about right? Have I missed anything? Thanks, Fred

[99yam40]

I would not think you would have to cut the HP fuel line to check pressure.
Maybe someone that knows that motor can give you info on where to measure rail pressure.

without measuring all of these things while problem shows up I do not think it will do much good.
you need to see what changes from when it works properly to when it messes up

[boscoe99]

I would not think you would have to cut the HP fuel line to check pressure.
Maybe someone that knows that motor can give you info on where to measure rail pressure.

without measuring all of these things while problem shows up I do not think it will do much good.
you need to see what changes from when it works properly to when it messes up

Correct. There is a tool that is provided by Yamaha so that a pressure gauge can be installed to monitor pressure in the fuel rail.

It saved Yamaha 25 cents not having to install a Schrader valve while shifting the costs of the special tool to the dealer and of course higher labor costs to the customer since the test procedure will take longer.

[99yam40]

looks like teeing in a gauge with the Yamaha tool (or just rigging it up yourself) with a long hose would allow you to monitor rail pressure while on the water.

doing the same for the lift pump would give you info if that one runs when it should also

vacuum gauge could be hooked up in line to tank in different places if you wanted to monitor that also while running

[Fred Pittman]

***...$142.00 for the adapter...too rich for me. What about this? Total cost with clamps $ .42

[Fred Pittman]

Maybe my brain has slowed down in my old age, but it seems to me that if I have NO restriction in the gas line from the tank to the lift pump is a vacuum gauge in this line gonna show much of anything?

[boscoe99]

Maybe my brain has slowed down in my old age, but it seems to me that if I have NO restriction in the gas line from the tank to the lift pump is a vacuum gauge in this line gonna show much of anything?

There will always be some restriction to fuel flow which can be seen on an absolute pressure gauge. Too little pressure drop generally indicates an air leak. Too much pressure drop indicates something abnormal that is overly restricting the flow of fuel.

The measurement needs to be taken at WOT for maximum fuel flow.

Most 0 ~ 30" Hg gauges won't have the fidelity needed to see small pressure values. What is needed is a mechanical gauge with a 0 ~ 8" Hg reading or better still an electronic digital gauge.

[99yam40]

***...$142.00 for the adapter...too rich for me. What about this? Total cost with clamps $ .42

looks like a good set up where did you find it?
or did you make it yourself?

[Fred Pittman]

It was part of a fuel pressure test kit from our loan-a-tool at AutoZone where I work. I can order this piece as a replacement part for the test kit from Autozone. Not sure of cost but I assure you it's cheaper than $ 142.00.....lol