F225 fuel problem??

[Kovalchick]

I was having a similar issue with my f225 it ended up being the on way check valve stuck open on the side of the VST and low pressure fuel pump, will drive you nuts when it sticks open. It make the engine starve for fuel and you can pump the bulb and it runs fine.

[dorado42]

Thank you KOVALCHICK....I had been advised to check this by RODBOLT17 and finally got around to replacing it. I am hopefully gonna go run the boat and see if the problem is fixed...have been working on trailer lately...will definitely post back the results.

[dorado42]

Still not fixed

OK...the bad news is the problem STILL exist. I thought the problem was fixed when I replaced the fuel relief valve by the low pressure pump (per RODBOLT) It turned out, not to be the case. The problem seems to be occurring when it is HOT outside. If I go fishing early morning, I do no thave the problem. As soon as it gets HOT, and I anchor the problem shows up. It is definitely something with the VST tank I think. I do not know what else to try!!! I guess I could spend another $250 dollars (2 motors 2 valves) and replace the fuel relief valve on top of the VST??? I spoke to Yamaha and they recommended I put a VAPOR RECOVERY KIT on the motors. The cost of the kit is approximately $800-$1000 and I am hearing the parts are not even available.

[rodbolt17]

some folks have reading comprehension issues.
I NEVER said to replace ANYTHING.
I did say to check some things.
all are easily tested.
if they pass the test why replace them?

ALL that VST is is a gas tank.
same as in every chevy,ford,plymothh ect,ect built since about 1985 with fuel injection.
its a place where the high pressure pump can get a clean bubble free supply of fuel.

google vapor lock

then explain how YOUR system is vapor locking.

it aint.

the VST vents to the air box.

if the VST vent leaks vapors into the airbox it can cause a rich condition cause the stupid ECU doesn't know there is extra fuel(vapors) in the airbox.
easy to test simply remove the vent valve from the airbox.

vapor lock is kinda like the old VRO on the OMC motors.
gets blamed for a lot of things but it actually doesn't happen.

if your stalling condition can be repeated its stupidly simple to check rail pressure when it fails.
if rail pressure is ok quit chasing fuel ghosts.

here on the NC coast out water temps stay in the 80's,our airtemps in the summer stay in the 80's low 90's and I have NEVER seen a vapor lock.

[rolrandy]

Don't know about the four strokes but my 99 200 OX66 has 2 vent like lines on the VST tank .. They got reversed and the tank was getting pressurized from the block instead of venting.
Just throwing it out there

[dorado42]

F225

OK, rodbolt I will CHECK as directed. The problem is not "repeatable." It does seem to be when it is VERY hot outside though. It seems to do fine before 1:00 or so. I will try the technique of "cracking the throttles" when I first start the motors after sitting for awhile. How long do I let the engines run (high idle) with the throttles cracked? I will report back this weekend. THANKS AGAIN!!!

[dorado42]

Rodbolt, I read your post again (I had looked at an old post about "cracking the throttles." You said to remove the "vent valve from the airbox." Is the vent valve the same as the "fuel relief valve" (part number 69J-13490-00-00) seen in the INJECTION PUMP 1 section of the parts for the F225? THANKS AGAIN and AGAIN!! I have had three other people contact me about having the same problem in the last two months....maybe this will help ALL of us!!

[dorado42]

Rodbolt...do I remove the vent valve all together or wait until the problem occurs and then remove it? I just want to make sure I am doing the test correctly.

[rodbolt17]

wont be the first F200/225 I have had in for service that ran 100+ hours with the VST vent dangling cause the last tech forgot to plug it back into the rubber holder.
IF I ran it with it removed I would try to find a way to vent it OUTSIDE the cowl.

but DO google Vapor lock.

fuel under PRESSURE tends NOT to vapor lock.

fuel under vacuum can due to the lower line pressure lowers the boiling point.
that's the WHOLE reason for a VST.

now if your leaking vapors into the airbox the ECU doesn't know it and adds fuel for a normal restart and it may be to rich.

[dorado42]

CaptSolo...thanks for your advice but it is not practical. The problem only occurs when the motors (seems) to exposed to very hot temperatures (heat of the day.) I have had it checked by the TOP mechanics in my area and they have all changed/suggested: 1) new fuel lines/hose clamps
2) new racor bases/filters
3) new low pressure fuel pumps
4) checked VST filter

They can NOT get the motor to act up while they are CHECKING. The problem seems to happen ONLY during the hottest part of the day. I can go offshore and the boat does fine (even after sitting on anchor) until after around 1:00 and then the engines start having problems. If I could find a Yamaha Mechanic who liked to fish for the day, that would be great then he could see the intermittent problem and address, unfortunately the ones in my area charge around $135.00 an hour to be on the boat ($1000.00 for the day). Rodbolt has accomplished more over the internet (legitimate possible problems -- not just replacing parts.) I think I will stay with RODBOLT as long as he does not start avoiding my post....LOL!! Thanks for the help!! The problem is simply that the problem is so sporatic no one can get it to happen on demand.

[dorado42]

Rodbolt....how would I know where this is...VST vent dangling....What does it look like and where is it located? I could remove it and run a hose out the top of the engine cowling (to vent the fumes), to see if it solved the problem. I will be on the water this weekend, so I could try it out!!

[rodbolt17]

the VST vent relief valve is that shiny looking metal cyl that plugs into the top port side of the airbox.

[dorado42]

Thank you rodbolt....i will check it out this weekend and report back. My thought was to plumb the vent relief valve directly out of the top of the cowling so any fumes simply get released to the open air (for testing purposes only...do not want to upset EPA) Do you think it would be best to do this to only one motor. My thought is if I do it to only one motor, then it allows me to see if one motor fails and one does not but it allows me to confirm the motors are still experiencing the problem (since the problem is not repeatable on command). It will be interesting also due to I am doing an overnight trip....so i will be leaving in the late morning and see if problem occurs when its hot, but does not continue when it is cooler (at night).

[dorado42]

Ok well the trip went pretty good. The problem only occurred AGAIN when it was late in the afternoon (hot). I had no problems when it was cool (in the morning). I did try cracking the throttle at restart (when it was hot) but it did not seem to help. Rodbolt is the next step to replumb the hose with the fuel relief valve going directly out of the cowling? Or do you have a different test? Thanks for your help. I now have four other yamaha owners experiencing this same problem that have contacted me, no one can figure it out????

[boscoe99]

Are the latest problematic motor pre modification status or post modification status motors? This post has been going on so long it gets confusing.

Might be better to start a new post and include the specific model identity or better still the engine serial numbers.