Fuel tank ???

[tommyr904]

I have been having some problem's the last few week's. i took it to the shop and they replaced the low pressure fuel pump,cleaned the high pressure pump,and VST filter.They ran it at 3500 rpm's and said it was good to go.I put it in the water yesterday and about 5 miles out it started the same thing again.It takes off and run's fine for about 5 miles then the RPM drop's to around 2500 and will not go any harder.if i let it idle for a few minute's it run's fine for a minute but get's worse as i try to make it in.I have changed the Racor and it was perfect,the pump's as stated and the fuel look's and smell's fine.I called the Tech this AM and he think's now it is the antisiphon valve.i pulled the fuel tank cover off but i do not see anything removable but the hoses.Any idea's?


05 2520 XL with an F250

 

[HM5]

I believe it is in the "nipple" fitting that screws into the welded tank elbow. It is what the fuel hose to the Racor it clamped to.

You might also try loosening the gas cap when the engine starts breaking up to rule out a plugged vent line.

FWIW I had to replace both of the low pressure pumps on my HPDI as well as the water sensor, VST and mid-pressure filters .

Hope this helps

 

[tommyr904]

seem's everyone is telling me it is the antisiphon valve.mine seem's to be under my baitwell so when it quit's raining i'm gonna take a look

 

[atlanticbeach]

You can remove the fuel line and take a small screwdriver and depress the ball in the anti siphon valve and see if it moves easily. Sometimes they get gunked up and will stick causing problems like you described. It is installed on tanks per the Coast Guard Regs to prevent unknowingly draining gas from the tank should a line rupture somewhere and you are not around. They mostly are a pain in the backside. You can remove it with no problem or just take the valve or nipple off the tank and clean it with carburetor cleaner good and put it back in.

 

[tommyr904]

I pulled it out and it was stuck shut.should i replace or just put it a brass nipple?

 

[HM5]

OH! another subject for debate
From what I have read, they can be successfully cleaned, but I think that I would replace it with a new one. Then throw the old one into the spare items drawer... next to the pair of rebuilt Yammie low pressure fuel pumps.

 

[tommyr904]

well i pulled it out and put a brass nipple in and no change.what next?

 

[tommyr904]

well i pulled it out and put a brass nipple in and no change.what next?

When boat slows down, what happens if you pump bulb?

it pick's up and run's for a minute or 2.i also noticed that just before it start's to die the flow meter start's dropping

 

[HM5]

well i pulled it out and put a brass nipple in and no change.what next?

When boat slows down, what happens if you pump bulb?

What Optimaxfish suggested is important and also you might also try loosening the gas cap when the engine starts breaking up to rule out a plugged vent line.

If the vent line is restricted, a negative pressure is created in the tank and the low pressure diaphram fuel pumps can't overcome it, so they run out of gas

 

[HM5]

it pick's up and run's for a minute or 2.i also noticed that just before it start's to die the flow meter start's dropping

That sounds like what happened to me this fall and I replaced BOTH low pressure pumps

 

[tommyr904]

Does that mean you have either a fuel restriction or a vacuum leak somewhere? Guess the fuel meter's dropping cause less fuel is passing thru. Could there be some crud @ the fuel management sending unit? It's easy to check.

any chance the tank vent is restricted? Some say fuel vapors can condense in low spot and act as a plumbing P-Trap.

i ran it with no gas cap on after it did it the first time and same.

 

[tommyr904]

well i dropped it off at Chelsea Marine today i'm done.thanks for the help.I will let you know what happens

 

[tommyr904]

there is a inline fuel filter between the 2 fuel pump's.can noy believe the first tech missed it.

 

[Megabyte]

there is a inline fuel filter between the 2 fuel pump's.can noy believe the first tech missed it.

So the problem has been corrected with the replacement of the inline filter?

 

[tommyr904]

there is a inline fuel filter between the 2 fuel pump's.can noy believe the first tech missed it.

So the problem has been corrected with the replacement of the inline filter?

yes they ran it and i ran it today for about 15 miles with alot of WOT 5900 and it ran perfect.


when he showed me the filter i could look and see the black crap inside of the filter.the tech said the crap came from the low pressure pump.he did not want to bash any tech's but he said if the other tech cleaned the VST tank like he said he should have seen it.

 

[tommyr904]

If anyone has replaced this filter, maybe could post how-to? I've got a spare and can't quite determine how, or what clamps to use?

IMO, poor Yamaha mech to miss it. I found it very easily in the service manual.

Totally agree and i let him know this also.I have used him several times with great result's but he sure missed this one.I had to tow 400 miles because of his screw up.