F115 losing power after about 3 minutes

[Snyd1437]

We have experienced intermittent loss of power on our 2013 F115 but thought we had solved the problem by replacing the fuel, fuel line, filter and bulb. This week the engine actually stalled while my son was running it at high RPM cruise for about three minutes. When I checked the new blub, it was "deflated" and I couldn't get it to regain its shape. The engine will run again if you restart it and run at lower engine power. The blub is just an Amazon generic, so perhaps that was a mistake, but I'm wondering if I have a clogged vent and the fuel pump is pulling a vacuum that collapses the bulb? The engine runs great otherwise.

[99yam40]

remove the fuel cap to see if that helps.
if not then disconnect the line on the tank side of bulb


that should tell you about where the restriction is

[DennisG01]

Yup, do as mentioned above. When you remove the fuel cap, you bypass the venting system - essentially creating a vent through the fill hose.

Did you replace the fuel line all the way from the tank? Assuming yes, if you still have a problem... clogged pickup tube or anti-siphon valve. Does your boat use an AS valve in the 90* fitting on the tank or does it use an electric valve located in the fuel line?

[Snyd1437]

I only replaced the fuel line to the water separator/filter (approx 24") due to sun exposure. I just tried using the bulb and it eventually filled, but once it filled, it felt like there was some vacuum building up.

That's a good point about a clogged pickup and/or AS. Based on these pictures, does my 90 look like it's an AS built-in (2007 Hurricane)? https://photos.app.goo.gl/j7z5BjHtnE99rodR8

I will say that the last time I used an electric fuel pump to pump the tank, it was really slow. Not positive if it was the pump, or this problem. I did order a new Yamaha bulb just to eliminate that source as well.

[RedwoodInfrared]

Every time I've seen this happen it was an obstruction in the pickup tube. If you have the electric fuel pump handy it might be useful to try reversing direction of the flow with a temporary tube and circulate the fuel back into the tank through the main pickup tube, which should free up the obstruction. I've cleaned up sediment and moisture in more than one tank by doing this with a course filter and fuel water separator in-line and just letting it run for several hours or until both filters stop accumulating anything undesirable.

I only replaced the fuel line to the water separator/filter (approx 24") due to sun exposure. I just tried using the bulb and it eventually filled, but once it filled, it felt like there was some vacuum building up.

That's a good point about a clogged pickup and/or AS. Based on these pictures, does my 90 look like it's an AS built-in (2007 Hurricane)? https://photos.app.goo.gl/j7z5BjHtnE99rodR8

I will say that the last time I used an electric fuel pump to pump the tank, it was really slow. Not positive if it was the pump, or this problem. I did order a new Yamaha bulb just to eliminate that source as well.

[fairdeal]

Based on these pictures, does my 90 look like it's an AS built-in (2007 Hurricane)?

Yes:





If the hose attached to it remains above the level of the top of the tank

until it leaves the boat to go to the engine,

then it serves no purpose anyway;

rather than replace it with a new antisiphon valve,

replace it with an ordinary hose barb.

[Snyd1437]

Thanks everyone for the suggestions. I will try both the AS replacement with barb, and reversing the flow. I’ll report the results.

The tank is not the easiest to access, so the cleanse will be “plan C”

[99yam40]

you have not ruled out the vent being plugged yet,
or the line or bulb

[Snyd1437]

This is true. I did open the gas cap while squeezing the bulb but didn't notice any difference...not the same as a WOT 4-cylinder though. I plan on trying that too. It's hard to see how the vent could be plugged. To me it feels like the most likely causes would be with the fuel pickup (clog) or AS valve (moving parts) as a vent is fairly bullet proof, no?

[99yam40]

so the bulb did not expand back out when you removed the fuel cap?
just saying do the easy things to begin with

[Snyd1437]

I removed the AS ball from the barb and noticed there was around 5 extra feet of fuel line so I shortened it.

Ran the motor for 10 minutes on the hose and the bulb did not get sucked flat and I was able to use the bulb to fill the small reservoir on the motor. On-the-water testing tonight...

fuel-line.png

[Snyd1437]

Huge THANK YOU to everyone, but especially DennisG for suggesting the anti-siphon valve. I think this problem has been dogging me for the last two seasons and just about ruined this last boating season with my oldest son (heading to college). We took the boat out on the Rapphannock (Chesapeake Bay) and ran clear across the river in white caps. The engine has never run better. I could not be more pumped and relieved and the family is quite happy too:

fuel-solution.png

[DennisG01]

Great! I can see the smile on someone's face there!

Just for giggles, split that fuel hose open and/or at least feel for soft spots. There's a possibility that the fuel hose could have been the culprit (failing internally) since you got rid of that at the same time you got rid of the AS valve. I'm just curious to know which it actually was

Just for reference, AS valves can be usually be cleaned out with Brakleen (and/or aren't expensive to replace). And, while it's true (as mentioned above) that they "generally" serve no purpose if the fuel line stays above the height of the tank... if a fuel line should rupture, it could fall below the height of the tank and then siphon fuel out of the tank into the bilge. This could potentially cause an explosion depending on what equipment is in there, but it will most likely start to get pumped overboard by the bilge pump which is not only bad for the environment but could lead to HUGE fines by the EPA.

Now, in reality, if a line ruptures you're going to know it since the engine will stop. The question is, will you figure out the line is the problem quickly enough - and then be able to plug/repair the hose (will there be easy access to the failed area)? Chances are a ruptured fuel line is not something most will think of/check right away so at least a good amount of fuel will get pumped into the bilge.

This said, I'm not saying you SHOULD put an ASV back in there - just trying to prevent both sides of the story so you can make a proper decision.

[Keithbaja]

Electric valve in fuel line ? Not in the scope of small vessels such as on this blog. No such critter . ABYC H-24 mandates along with CFR part 33 anti sipion valve regs along with EPA and CARB all have standards. Home of the Bra, land of the FEE

[DennisG01]

Electric valve in fuel line ? Not in the scope of small vessels such as on this blog. No such critter . ABYC H-24 mandates along with CFR part 33 anti sipion valve regs along with EPA and CARB all have standards. Home of the Bra, land of the FEE

This is incorrect. Small boats CAN use the inline, electric shutoff valve. Besides, we don't know what vessel the OP has - this forum is about engines, which can be used on any size vessel. It's up to the boat manufacturer to decide whether to use an AS valve or an electric valve.