'03 F200txrb stalling near idle

[gazman51]

I'm a captain and USCGAUX coxswain in SW Florida, new to this forum and impressed by many of the replies to various threads and recommendations. Now to my problem....I have been running an '03 Grady with twin F200txrb series engines (525 hours each) for about one year. I live in SW Florida where temps can exceed 90 degrees for several months. Both engines ran troublefree for about six months after I purchased the boat (last september). In June the port side engine started to stall out at low rpms (after running for 1/2-1hour or longer). The problem became more frequent as the summer progressed and the starboard side engine began doing the same thing about one month ago. All of my fuel is from the same source (<10% ethanol and always filled from the same vendor). Both engines, feeding from the same fuel tank with separate pick ups, went through a complete 100 hour maintenance schedule last month. This was done by a local certified and experienced Yamaha mechanic. The problems persisted after maintenance and all fuel, fuel lines plus filters were checked and/or replaced. A Yam "master mechanic" and the service manager from the local dealership have now spent 8 hours troubleshooting+my$$ and they now want to spend more time+$$ running the boat on separate fuel tanks which I already did with the other mechanic. After all this, the primary recommendation that they are making is to install the Yam "canister modification kit" #90891-40430-00 on both engines. Unfortunately Yam no longer sells this kit which was priced around $350. Priced out separately, these parts now cost more than $700 per engine...ouch! Is there any other approach to resolve what seems to be a fuel vapor recovery (or release) problem cause by high operating/environmental temps?? Yamaha will not provide any form of financial or technical support to me or the dealer. I now have a $50k boat that can only be (safely) used in colder weather. It is apparent that Yamaha made this modification (or retrofit) later engines beginning in 2004 after they realized that this engine design had a warm weather operating problem. Please help.

[rodbolt17]

if your tell tale is working your fuel cooler is clear.
that kit wont help at all.
now on to the issue.
carefully test the relief valve at the top of the airbox on the port side.
that is the VST vent.
if it leaks fumes(vapor) can drawn into the airbox under certain conditions.
then on to the main culprit of low RPM stalling.
carefully check the 10 PSI relief valve between the VST inlet and the lift pump inlet.
if it leaks the VST gets lower and lower on fuel until it runs out and the only way to restart it is pumping the fuel primers.
will do it if you have ANY airleaks in the system.
last on I did it was corrosion on the water separator housing where the filter gasket bonds.
leaked just enough to stall it at low speeds but above 1200 RPM all was good.
the reason you ask????

below 1200 RPM the lift pump cycles, 10 seconds on 20 seconds off.
you can watch it by simply observing the fuel cup on the engine.

[TownsendsFJR1300]

If you cannot get it straightened out, bring down the boat to Walker Marine, south of Ft Myers Beach.

They have an excellent Master Mechainic that has worked on my engine and knows his stuff. Very fair on prices and all they work on is Yamaha's About a 30 minute run past the Sanibel Bridge by water. By trailer, 3/4 the way down Estero Blvd on the left.

Yamaha Dealer Locator, FL||

[boscoe99]

carefully check the 10 PSI relief valve between the VST inlet and the lift pump inlet.
if it leaks the VST gets lower and lower on fuel until it runs out and the only way to restart it is pumping the fuel primers.

Rodbolt, have you ever come across a relief valve that was failed closed? If so, what were the symptoms?

Did it result in the lift pump flooding the VST, did it shorten the life of the pump, does it cause excessive current flow through the pump and maybe blow a fuse, or ???

There have been lots of comments about a relief valve failing open, or maybe getting weak and not maintaining sufficient pressue, but I don't recall hearing of one that was over pressurizing the line to the VST.

And, did you test a relief valve to come up with the 10psi number? I have not seen an actual number stated in any Yamaha document.

[rodbolt17]

never saw one fail closed.
probably would not hurt much other than increase pump wear.
typically the corrode inside.
the valve body is AL and E fuels eat on it.
there is an actual spec but I tested a new out of the bag valve.
why there is a relief valve on the VST vent I am not sure.
but if it sticks open vapors can be drawn into the air box.
if it sticks shut repriming the VST is all but impossible.

typical symptom of the lift pump relief valve leaking is a customer complaint of stalling at low speeds and having to pump the primer for a restart.

you can watch the fuel level rise and fall in the engine filter cup.
after about 10 min you will note the cup is lower and lower on fuel after each cycle.
typically means either you have a minor air leak in the system, filter heads are NOTED for corroding at the gasket surface yet no one bothers to check them, or that relief valve is leaking.

[gazman51]

Thanks for the feedback and recommendations. I will check the relief valve on the VST and filter heads. I may have picked up 1/2 tank of E10 fuel and was wondering if the ethanol content would contribute to the vaporization problem?

[gazman51]

Thanks for the recommendation. I'm working with the "master mechanic" and service manager at Fishtale Service. I just hope that they can correct the stalling problems before I run out of money.

[rodbolt17]

get the stupid vapor thing out of your head.
fugggitt abooot it.
IF it makes you feel bettaaa simply REMOVE the VST vent line from the airbox and retest.
if it still stalls it aint the vapors.
like I say, there are TWO relief valves.
one is for vapor control and VST venting.
the other is to maintain about 10 psi to the VST fuel inlet.
its NOT covered in any Yamaha class and most techs have no clue why or what they do.

[gazman51]

'03 F200 Engines - Running Better

Just a follow up note to let you know that I ran the boat for over an hour this afternoon from idle speed up to WOT and then back down to idle speed returning to the dock. Bay water temp was 90 and air temp was 93 so fuel had ample time to warm up. Both engines performed well and did not stall out. The only significant change was the addition of 90 gallons of (supposedly) ethanol free fuel which should have brought the total tank ethanol content below 5%. All other engine conditions remained the same. I'm now wondering if the "head pressure" of a full fuel tank reduced vacuum in the fuel lines which enabled the low pressure pumps to do a better job of filling the VST tank? The marina mechanic claims that they checked all valves and venting. I'll only be convinced after running the boat with a full crew/load next weekend.

Many thanks for the recommendations and help.

[rodbolt17]

there is only ONE lift pump.
at speeds below 1200 RPM that lift pump runs in cycles.
10 seconds on 20 seconds off.

[TownsendsFJR1300]

Just a follow up note to let you know that I ran the boat for over an hour this afternoon from idle speed up to WOT and then back down to idle speed returning to the dock. Bay water temp was 90 and air temp was 93 so fuel had ample time to warm up. Both engines performed well and did not stall out. The only significant change was the addition of 90 gallons of (supposedly) ethanol free fuel which should have brought the total tank ethanol content below 5%. All other engine conditions remained the same. I'm now wondering if the "head pressure" of a full fuel tank reduced vacuum in the fuel lines which enabled the low pressure pumps to do a better job of filling the VST tank? The marina mechanic claims that they checked all valves and venting. I'll only be convinced after running the boat with a full crew/load next weekend.

Many thanks for the recommendations and help.

Do you know what they ended up doing to the engines specifically?

Please post how your final, test run works out...

[gazman51]

The "sea trial" yesterday demonstrated that the engines are now performing normally again, e.g. they are not stalling at or near idle speeds as before. I've asked the marina for details of what specifically they did to both engines and asked for documentation with the yard bill since I'm being charged $100/hour. When I have the detail, I will post it on this forum. They did not replace any check valves or other parts on either engine. Thankfully, I made the decision not to order (or install) the "canister modification kits" on either engine. Clearly, the '03 F200 engines are more sensitive to running in hot climate conditions but I am still unable to determine why they were stalling for the past two months.

[TownsendsFJR1300]

Thanks.. See you out on the water!

[TownsendsFJR1300]

Just as a side note, when my F150 was still under warranty, I had the same issue, stalling coming into dock, 600 RPM and lower. (should be 700+/- 50 or so in neutral)

Brought it to the dealer in Cape Coral, (7th terr) they replaced the entire TB assemblies!!

I know it didn't need it, then they tried to charge me +$1,000. Ding, ding, its under warranty, don't think so.

It did work ok after that but eventually dropped again.

Stopped back in there to get the idle bumped up, watched them tune a terrible vibration into the engine (the engine actually walked itself to one side from the vibration) it was that bad. They said that vibration is normal and left it..

That's when I went to Walker Marine and their Master tech was able to get rid of the vib's and its idled correctly (better than new) ever since. They treated me good, I know they didn't charge me fully for the time the tech had into it. I think it was a combo of the TPS, the sync and ??

I know they didn't replace the idle control valve..

[gazman51]

Scott - Thanks for the info on Walkers Marine. Sounds like they have an excellent mechanic and glad to hear that he fixed your 150. Prior to my present Grady, I had a World Cat with twin Yam 150 OX66 (2stroke) engines. They were very reliable except for some electrical problems which is to be expected with engines approaching 12 years old.

FYI and for other readers on this forum, the mechanic who worked on my engines checked the following items (before recommending a different source of fuel):
checked fuel lines/system for leaks and/or restrictions
vacuum tested fuel lines (before and after lift pump)
checked anti-syphon/check valves
checked fuel cooler
checked fuel pressures (all within spec)

Today, I ran the boat from Big Carlos Pass to Wiggins Pass at 4000-5500 rps and then through several no wake zones back to my slip. Thankfully, then engines never stalled out and I believe that the new "zero ethanol" fuel is a must for my engines. Happy boating!

Captain John