F225 fuel problem??

[dorado42]

I have a pair of 2002 Yamaha F225 TXRA --- a week ago I was running 3500 rpms and suddenly port motor gradually lost power. I checked the water fuel seperator and all was good. Filled filter back up and reinstalled but could not get primer ball to get hard. Replaced primer ball and seemed to be ok. Ran 50 miles offshore and boat ran great. After fishing for a about 30 minutes went to start boat....would not start and ball would not get hard. Had to keep filling water fuel seperator with gas from a portable can to get the ball hard. Once it started and got on plane would cut out and had to keep pumping ball for a minute or so and then motor ran fine all the way home 50 miles. I replaced antisiphon valve. When I went back out same problem....but now starboard has similar problem...but the primer ball gets hard on that side after only a few squeezes. I am replacing all fuel lines (just because I do not know how old they are, just bought the boat). I was wondering if this sounds like a VST filter problem?? I can hear the low pressure fuel pump run when key is first turned on...so I know it is working. Can the diaphram be bad so even though the pump is running not enough pressure?? any help would be greatly appreciated.

[rodbolt17]

low pressure pump only runs if the engine is running.
no diaphragm pumps on that engine.

[dorado42]

Thanks rodbolt....does this seem to be a VST problem....thought maybe changing VST filter, "F" filter and checking engine fuel element to make sure cup is tight....do you agree??

[dorado42]

Thank you for the reply....i checked the fuel tank, pick ups and racor filter and they are all clean. If it was fuel restriction why would boat run fine at 4200 rpms (cruising speed coming home from offshore 40 miles). The boat has two seperate tanks, lines, filters etc, but same problem with both motors...port is just worst than starboard

[dorado42]

I came home at 4200 because that is my cruising rpm...WOT is about 5700-5800...the boat will run at 4200 rpms all the way home and never skip a beat...problem only seems to happen when first accelerating after motors have been turned off (while either anchored or drift fishing) and both motors seem to do it.....just port is worst than starboard....port primer ball is very hard to get hard, whereas starboard just needs a couple pumps....pulled fuel pick ups the screens were clean with no signs of dirt

[Bilge Rat]

Try remote fuel tank to rule out onboard tank/fuel issues.
Fuel lines will cause issues you describe. Cut the line open lengthwise to inspect condition. If age is unknown replace them.
Check all connections in the lines for air leaks and the filter seals.

Get a fuel pressure gauge and run the motor, look for pressure drop at the problem RPM.

[dorado42]

Ok...still having problem...according to Yamaha the signs are definitetly a "vapor lock" problem.....which is what I thought. Yamaha advised to check the fuel cooler on side of VST tank. They claim that maybe the water circulation side is clogged/restricted and this may be causing a vapor lock....will tackle this in a couple of days.....will post back with results....motors turn 5400 RPMs with 1/4 tank, 3 average sized guys and full trim DOWN---is this the correct RPM range?

[99yam40]

I do not see how vapor lock would keep the primer bulb from firming up when pumping it.

Think the 4 strokes turn 6000.
Owners manual should tell you

YAMAHA MANUAL STORE

[rodbolt17]

have you a clue what vapor lock is?
why to you think its called a VST?
vapor separator tank.

sounds like a clogged filter to me.
or a bad check valve.

[dorado42]

well yes, I do know what vapor lock is -- but maybe you should educate me more --- find it harder to believe that both fuel filters clogged at the exact same time -- I have a better time believing that BOTH fuel coolers may have some restriction than both racors clogging at the same time. Which "check valve" are you referring to --- the ball not getting hard was fixed by replacing the primer ball as well as tightening the new anti-siphon valves (not sure which one actually made the difference) -- but did not cure the main problem

[dorado42]

Hey rodbolt....it iwas filter related, would it not be a problem all the time, not just after the motor gets hot, as well as only when the motor is trying to build power. I would think a filter restriction would cause the problem all the time...but please let me know what you think.

[dorado42]

rodbolt17...sorry I left the 17 off before...but yes I have already pulled the VST tank and the filter was very clean....actually am starting to think VST stands for "very strange thing" or what I wish it was a "very simple thing"...LOL..just have to laugh because this is driving me crazy!!! Thanks for all your guys help....still hope it is the fuel cooler...I gues they are going for a muriatic acid bath....hahaha!!

[rodbolt17]

if the tell tale works the fuel cooler is clear.
vapor lock is when the fuel actually boils.
fuel under pressure has a much higher boiling point than fuel under vacuum.

there is a 10 PSI check valve between the fuel lift pump intake and the fuel inlet to the VST.
if it fails the VST cant stay full especially at low speeds.

[dorado42]

Thanks rodbolt17....another item I will check....it seems as though it might be the first thing I check to avoid taking fuel cooler apart for nothing...can you tell me how to check the check valve....also Yamaha is the one stating it was vapor lock issues....so thAnks for the explanation...will keep u updated tomorrow

[dorado42]

Well the fuel cooler was not too bad....a little corrosion, but no blockage....check valve was good also...so back to square one......so very confused...anymore helpful hints from the experienced...please help