2014 F300 bogs down and quits.

[Mytoolguy]

Was out and running at cruise and all of a sudden it actually felt lie we hit something but turned out the port side just quit.

Started right back up and away we went. Seemed fine rest of the day but on the ay home every time I got the motor over 3K rpm it would do the same, bog down and quit.

No issues with it starting right back up and running as long as it was under 3K.

primer bulb was getting soft and would get hard when squeezed with the engine running but not get hard if the motor was off?

Everything is basically new ( fuel line, primer bulbs, racor's ) as these were installed this past August/ September

Fuel tank new a few years ago with 2 separate pick up

Just trying to get some ideas before I get into it.

Thought's?

[99yam40]

sounds like lack of fuel to VST.
monitor the rail pressure and pressure to VST to verify what is happening.
possible sucking in air, restriction on intake, or recirculation valve sticking open

[Mytoolguy]

Can this be done accurately at idle?
I did rev it up in neutral seem to be jumpy around 2.7 to 3K rpm but smoothed out after.

Just wondering if i have to test with a load on it.


And would lack of fuel to the vst create the primer not getting hard?

[99yam40]

testing needs to be done when the problem shows up.
did you pump the bulb to see if that helped when the motor was bogging down.
reving with no load tells you nothing.
motor needs more fuel when loaded

[Mytoolguy]

We did not try to prime when the problem happened.
the primer only got hard when the motor was running.
Changed out the bulb no difference. Swapped port and stbd fuel lines on the racors and got a soft bulb on the port side still.

changed the on the motor filter and the housing came off remarkably easy, was able to unscrew it by hand.
I heard they were a issue to do and deal with but it was only hand tight (actually both motors were the same)

made sure everything was right and tight and the primer seemed to hold pressure now?

gonna run it see what happens and if not fixed Ill pull the VST at that point I guess.
just hoping it's not a HP pump.

[99yam40]

the pump in the VST uses fuel to cool and lube the pump(flows thru it),
so if the VST runs too low on fuel the pump cannot pump fuel that is not there so it can be damaged.
I hope your problem was just sucking air at a loose connection at the filter and did not harm the pump.
let us know how it goes

[Mytoolguy]

So took it for a test run.
Seem much better at 1st ran well for a few minutes then Im guessing once it was getting warmer it bogged and quit again about 3.8K rpm.
but this time the primer bulb was easily back to hard in 2-3 pumps even with the motor off.

Will be getting into the VST next.
Luckily I have a complete spare here if needed.

Also something else which is really strange
At 3400 RPM I would get about 22kts and burn 1.8GPH

Today at 3200 RPM about 19kts and burning 1.3 to 1.4GPH

So now with this condition happening I am burning more fuel?

[99yam40]

to me it Looks like lower RPM, lower speed, and lower fuel use from what you wrote.

still need to know if rail pressure and pump pressure to VST are staying inspec or not

[Mytoolguy]

to me it Looks like lower RPM, lower speed, and lower fuel use from what you wrote.

still need to know if rail pressure and pump pressure to VST are staying inspec or not

Ordered a fuel pressure tester Ill have tomorrow.
If I get the 40 psi on the rail does that typically mean that the HP Pump is fine but the filters need to be changed/cleaned?


My speed matched what I normally do at cruise the 3200 rpm it was just a typo. getting lower GPH @ the same speed and rpm now.

[99yam40]

if the rail pressure stays in spec, then you know the pump is working properly and that it has enough fuel to pump.
if it does not stay in spec then you need to find out why.
VST running too low on fuel is one reason

[Mytoolguy]

Well I took apart the VST and HP filter was dirty.
I actually had an extra clean set with my VST so I swapped them both out and will take for a test run in the next couple days

[oldmako69]

My 225's did this all the time. Motor runs fine till 'X' RPM and then the restriction prevents enough gas. It got to the point where I was having to clean my HP fuel pump intake screen every ten hours or so. There is no need to replace them, just shoot em with carb cleaner.

Are you running ethanol? In my case the e10 was corroding the fuel line internally and the excess fuel in the fuel loop was delivering that crap back to the VST. I ended up replacing the fuel lines on the engine (from the VST to the injectors and then back to the VST). I am not yet familiar with the set up on the 300, so I may be FOS. I'll likely know more this season since I just bought a set.

Let us know what you found.

[Mytoolguy]

So when taking apart the VST I may or may not have found a small piece of flaked off fuel line (or so it appeared to be). When I dumped the VST I thought I heard it hit the coffee can I was dumping the fuel in but can't say for sure if it was already in the can. i am hoping it was in there because that would also make sense that the piece was small enough and just the right shape to cover the HP filter.

I am lucky that I have plenty of access to non-ethanol fuel, but these motors came from Texas and not sure what they run there. I keep forgetting that these came from another state and I need to keep in mind the issues with ethanol fuel. When I did install the motors I installed all new everything fuel related. I appreciate all the feedback. Once i get a good weather window Ill be going for a test run and report back.

[Mytoolguy]

Well decided I didn't want to wait so took it to the bay for a couple hot laps.
Started out well then about 3700 rpm it cut out, but as usual started right back up.
Went for another lap had it up to 4K rpm no issues then bumped to 4500 then to 5K for about a 1.5 minute's and seemed to hold no issues.

Going with air still in the system for the 1st and only cut off during the test runs.

Hope this helps with others that may be facing the same issue.

Also just on another note, This was the 1st time I have taken off and apart a VST.
After watching a quick video the entire job took me about 3 hours with some breaks for pictures and referencing diagrams to make sure I was putting all the hoses back where they belong.

Was a relatively easy job and seemed more intimidating then it actually turned out to be.

[99yam40]

I hate to say it, but I do not see how air could get into the VST unless it was being sucked in from the lift pump side