2006 F250 Fuel Smell & Leak Key On

[ZooKeeper]

We recently purchased a boat with twin 2006 F250 TUR. Recently one engine starting spitting fuel from the exhaust and would stall at idle. We shut it down and when I came back to check it out, I realized that fuel is leaking from the exhaust port even when the engine is not on, but key is on. Before I start tearing into things, I was hoping to be pointed in the right direction. From what I’ve read so far, I was going to start with the VST and make sure something is not stuck open? I do hear a humming when the key is on, and I would assume that’s a fuel pump. Appreciate any help.

[fairdeal]

The continuous hum with key on is the electronic throttle valve -
that controls the flow of air, not fuel.

If you listen carefully when the key is first turned on,
there will be another faint buzz - but stops after about 3 seconds -
that's the high pressure fuel pump, pressurizing the fuel rail.

I've never heard of fuel 'spitting from the exhaust' -
I assume you mean the 'idle port', in the back just below the cowling ?
are you sure that is fuel coming out ?

The VST can overflow out its vent -
if the needle valve/float mechanism doesn't seal correctly -
but fuel is supplied into the VST only when the engine is running -
so it shouldn't be able to overflow just with 'key on"

I'm leaning more toward an injector stuck open...

[ZooKeeper]

Thanks for the quick reply. I was referring to the idle exhaust port. When it was running, I held my hand in front of it and got fuel spit all over my hand. So I assume just a lot of unburnt fuel getting exhausted? I pulled all the plugs and all are black and sooty, so all cylinders are getting too much fuel somehow. A stuck injector should show one cylinder as the issue I would think? I no longer am getting the fuel from the idle exhaust with only key on, but the boat is on a rack and when I first got here and turned the key on, I was getting fuel dripping from the skeg and I followed up to the idle exhaust port, but it’s possible it was coming out of the cowling. Thanks again for any suggestions.

[rejesterd]

Since all plugs are fouled, I would replace them and then check the pressure regulator. You need to apply vacuum presure to it and see if the fuel pressure changes accordingly (the service manual tells you how to check this). I would also check the VST needle valve for damage/bends and check the float as well. If all that stuff checks out ok, then I would say your injectors need to be cleaned or there's an issue with ignition.

[ZooKeeper]

Some additional info, not sure what might be helpful:

1. I removed both intake manifolds, noted a puddle of fuel under the oil dipstick that must have occurred during today’s work even though I never started the engine? Couldn't find an obvious source, but perhaps this is indicative of something? And this was likely the source of the smell noted in my OP during key on.

2. Ran YDS and got the following codes, engine currently has 708hrs:

72 Cam Pos Sensor Port Int 627h
17 Knock Sensor 698h
24 Cam Pos Sensor Exh 698h
71 Cam Pos Sensor Stbd Int 698h
29 Intake Press Sensor 708h

3. There is a very slight fuel smell to the engine oil, probably to be expected with the other symptoms.

Been searching here and haven’t been able to find any similar symptoms. Is it possibly the T-stats, as I read a few threads where these being stuck can cause fuel issues?

[ZooKeeper]

Since all plugs are fouled, I would replace them and then check the pressure regulator. You need to apply vacuum presure to it and see if the fuel pressure changes accordingly (the service manual tells you how to check this). I would also check the VST needle valve for damage/bends and check the float as well. If all that stuff checks out ok, then I would say your injectors need to be cleaned or there's an issue with ignition.

Thanks, I’ll get to this and report back. A couple of pics of the plugs attached.

[rejesterd]

Some additional info, not sure what might be helpful:

1. I removed both intake manifolds, noted a puddle of fuel under the oil dipstick that must have occurred during today’s work even though I never started the engine? Couldn't find an obvious source, but perhaps this is indicative of something? And this was likely the source of the smell noted in my OP during key on.

2. Ran YDS and got the following codes, engine currently has 708hrs:

72 Cam Pos Sensor Port Int 627h
17 Knock Sensor 698h
24 Cam Pos Sensor Exh 698h
71 Cam Pos Sensor Stbd Int 698h
29 Intake Press Sensor 708h

3. There is a very slight fuel smell to the engine oil, probably to be expected with the other symptoms.

Been searching here and haven’t been able to find any similar symptoms. Is it possibly the T-stats, as I read a few threads where these being stuck can cause fuel issues?

Ok, given those codes, it seems your cam timing is off. That could be due to a stuck oil control valve, a clogged OCV filter, a clogged oil passage, or a stuck VCT. I would get the service manual and check those things, since those are mostly recent codes. Might also want to check the air pressure sensor as well.

[ZooKeeper]

Ok, given those codes, it seems your cam timing is off. That could be due to a stuck oil control valve, a clogged OCV filter, a clogged oil passage, or a stuck VCT. I would get the service manual and check those things, since those are mostly recent codes. Might also want to check the air pressure sensor as well.

Thanks, I am going to run through the svc manual tests for all these.