F250XCA dies under load

[ntxwatercraft]

I have a 2014 F250XCA that runs great most of the time. After leaving the marina and rev to 3500+ it will die. I pump the bulb and it restarts fine and will run great for a few minutes. If I run below 3000, it will run all the way across the lake.

If I try to pull the tube with the kids on it, the motor will die after 15-30 seconds.

Is this a fuel pressure issue or an air leak? Should I start with replacing fuel filters?

[DennisG01]

Sounds like a supply issue... tank, pickup, lines, filter... really, anything from the tank to the injectors. Try running with the fuel cap off to see if there's a restriction in the vent system. Also, monitor fuel pressure at the rail before/during/after the event - that will help narrow things down. If you don't do some diagnostics, you'll be stuck replacing things "just because", which is not the right way to do it. If you're not comfortable with this stuff, it would probably be worthwhile to have a shop look at it for an hour or two.

[ntxwatercraft]

Thank you, Dennis. I will go run it around this evening with the cap off and post tomorrow.

[DennisG01]

Although fuel quality is very unlikely to be the issue, it wouldn't be a bad idea to dump the contents of the onboard fuel/water separator (filter) into a glass spaghetti jar and observe. Also, drain the VST tank for the same reason. How's the on-engine fuel/water separator look?

Before you run with the cap off, observe the fuel bulb while the issue happens. If it flattens out, then see if removing the fuel cap prevents that from happening.

[Donnie Coulsting]

Had similar issues with my 250. Clogged VST filter. Run the rpms up and when it starts to die pump the priming bulb. If the engine regains power it’s either the primary filter or most likely the VST filter.

[ntxwatercraft]

It turns out it was the fuel. I burned off over half the tank and added 24 gallons of fresh premium. It runs like a top.

Thanks for everyone’s insight.

[99yam40]

something to think about,
adding fresh fuel to bad fuel will get you a lot more bad fuel
I hope your motor ends up OK burning all of that.
I guess these newer 4 stroke are not as bad as the old 2 strokes on that

[DennisG01]

It turns out it was the fuel. I burned off over half the tank and added 24 gallons of fresh premium. It runs like a top.

Thanks for everyone’s insight.

Hopefully that's it. Did you initially dump some of the fuel from the onboard filter to check quality before adding new fuel?

OR... how long did you run the engine after filling up? If it wasn't for very long, then when you opened the fill cap to add fuel that would have eliminated the vacuum created by a clogged vent. It may take a little time for it to build back up. If you ran the engine for a long time, though, hopefully you "fixed" it. In that case, you should also be changing the filter.

[ntxwatercraft]

I thought the problem was fixed, but I was wrong. The outboard still dies under load between 3200-4000 rpm. I assume this is a fuel supply issue or perhaps an electrical issue. I have checked boat side fuel system and replaced separator with Yamaha 90 gph. I dumped the separator and inspected the fuel (ok). I have replaced all fuel filters, including VST filters. I removed the injectors and had them tested and cleaned (ok). The problem persists. I am now focusing on fuel pumps. Could my problem be the low pressure pump or a fuse relating to it?

[fairdeal]

Could my problem be the low pressure pump or a fuse relating to it?

If the problem was the fuse for the low pressure pump,
then once the VST runs empty,
the engine will not start or run.

IF the problem is caused by poor performance of the low pressure pump,
then the engine will run perfectly,
so as long as someone squeezes the primer bulb,
and makes sure the VST is kept full.

Have you tried doing that?

[ntxwatercraft]

I appreciate the suggestion. I will try that.

Yesterday, after changing the VST filters, I left the boat idling at the gas dock while I pulled the trailer out. When I returned, I found that the motor had died. I had to re-pump the bulb in order to restart. This is the first time that the engine died while idling. This new development seems to point to the LP pump. Before ordering a $600 pump, I will try your suggestion.

[fairdeal]

If the pump fails, it usually is a complete failure to run.

However, many things can 'handicap' the performance
of an otherwise functional pump.

- a flow restriction - for several possible reasons -
on the suction side of the pump

(if there is a restriction between the primer bulb and the fuel tank
it will manifest in the primer bulb being 'sucked flat' while running)

- an air leak on the suction side of the pump

- a restriction on the pressure side of the pump

You say you replaced the VST filters -
so the screen at the base of the HP pump,
AND the odd little screen at the inlet to the VST?

Did you remove and examine the pressure control valve
that is 'alongside' the screen at the top of the VST?

[ntxwatercraft]

Those are the two filters(screens) that I replaced. I did not remove/examine the pressure control valve (relief valve) on the top. How do I remove and inspect this valve? On the schematic, there is also a pressure regulator. Could one of these be the culprit?

[ntxwatercraft]

New update. I checked the fuses and found the #4 fuse was blown. This is the 10amp fuse for the fuel feed pump. I replaced it and started the motor. After 30 seconds, I checked and it was blown again. Does this mean I need a new fuel pump? Does this fuse control the exterior LP pump or the internal HP pump?

Thanks in advance for your advice!

[fairdeal]

what I'm seeing,
the lift/feed/low pressure pump fuse is 10 amp
the HP pump is the the 15A

the lift pump only runs when the engine is running
but you should hear the HP pump run for a few seconds
when you first turn the key to on