Mercury 90HP 4 Strok EFI 2011 (90ELPT 4s Ser # 1B897873) - Fuel in Oil

[ShawnQ]

Good afternoon,

After doing some google searching I stumbled upon your site. I'm looking for help diagnosing an over-fueling situation on a 2011 90hp ELPT 4S Merc.

All fuel lines are brand new. It has a fuel/water separator, and had a fuel primer bulb mounted between the FWS and the outboard. I replaced it with a new one when I did the fuel lines, as well as a new fuel/water separator. I've read mixed reviews on whether or not the primer bulb is required, but since it was already there I put a new one on it.
Plugs and Pencil Coils are all new.
Compression was around 190psi on all cylinders, albeit cold
I didn't do a leak down.

When I fire it up, it runs rough, spits raw fuel out of the exhaust, and is diluting the oil. I have only run it on the water hose as it is in no condition to be on the lake/bay.
The air filter housing drips fuel when the key is turned on and the engine is primed. Low Pressure pump cycles on for a few seconds, and then shuts off, presumably when the float switch signals it to cycle off.
The bottom cylinder (#4?) has a wet plug and it runs rough on the water hose (haven't put it in the water yet).
The engine is clearly getting too much fuel.

I removed the FSM (which has been rigged at some point, evident by the broken screw mounting holes and rtv sealant in lieu of a gasket/seal). I tested the float switch, and it appears to be functioning correctly (continuity tested).
I noticed that both fuel pumps are new (aftermarket, but correctly cross-referenced, and they both run).

I noticed that the 'seal' on the bottom of the high-pressure fuel pump was not installed. What symptom(s) would this cause?
I noticed that the fuel pressure regulator hose 'nipple' that is part of the FSM cover was broken off, and a new hose was installed over the remaining stub which fits loosely and was held on with a zip tie. This was likely not air or fluid tight. The hose was also a little bit loose on the fuel pressure regulator, held on with a zip tie - again, not air tight. This hose itself was not cracked.

I'm wondering if I should just bite the bullet and buy a whole new FSM to rule out any of the potential issues in my existing one?
Could the lack of the seal on the bottom of the HP pump cause my symptoms? I'm not sure exactly what that seal is sealing from.
What about the poor seal on the fuel pressure regulator hose?
What about a sticking injector?

Any other areas to look on the engine would be helpful. I have not put a fuel pressure gauge on it as I really don't want to run it any more than I have to with the amount of fuel that is being mixed with the oil and coming out of the exhaust.

Thanks in advance for any advice.

[larryhyco]

I have the same engine on my pontoon. I do not believe you are suppose to have a primer bulb on that engine. I know mine runs without one. I also had to replace my float (which was bad) I also replaced the high and low pressure pumps while I had it apart.

[ShawnQ]

I pulled the injectors and having them checked to make sure none are sticking open.
I will remove the primer bulb, as well.

The pumps appear new, and the float is functional.

Now i'm worried about the fuel pressure regulator, and what a bad seal at the bottom of the high pressure pump would cause.

[SPORTMOD25]

I noticed that the fuel pressure regulator hose 'nipple' that is part of the FSM cover was broken off, and a new hose was installed over the remaining stub which fits loosely and was held on with a zip tie. This was likely not air or fluid tight. The hose was also a little bit loose on the fuel pressure regulator, held on with a zip tie - again, not air tight. This hose itself was not cracked.

The hose you are referring to is the fuel pressure reference hose and if damaged will cause the engine to run rich. also check your thermostat to verify it is working correctly, if it is stuck open it will cause the engine to run at too low of a operating temp causing the engine to "make oil"

[EuropeanAM]

Problem is in the FSM. Correct the broken/missing components, or replace the assembly so that you can enjoy the engine.

If pressure regulator reference hose is not AIR TIGHT, it's not FLUID TIGHT EITHER. And since it's hooked straight to the intake manifold, it's under VACUUM much of the time, literally sucking fuel up the tube and into the intake (unmetered fuel source).

Also note that there should be NO primer bulb on this model.

[ShawnQ]

Problem is in the FSM. Correct the broken/missing components, or replace the assembly so that you can enjoy the engine.

If pressure regulator reference hose is not AIR TIGHT, it's not FLUID TIGHT EITHER. And since it's hooked straight to the intake manifold, it's under VACUUM much of the time, literally sucking fuel up the tube and into the intake (unmetered fuel source).

Also note that there should be NO primer bulb on this model.

EuropeanAM,

Replaced the FSM cover (with the broken hose bib for the regulator reference).
Replaced the FSM housing (due to cracked lid attachment holes).

Fired it up, and it seems to be running smooth and normal. I haven't put it in the water yet, but it definitely sounds healthier, more smooth, and what most outboards sound like.

Question - with the fuel pump on these engines - will it run the pump every time you turn the key?
If I turn the key, I hear two pumps running. One shuts off, and then the other. Maybe 7 sec and 10 sec. If I turn the key off, and immediately back on, they both run the full time again. Is this normal? I checked the float, and it was functioning correctly per the voltmeter.

Thanks for your help. Hopefully I can water-test it soon!

[EuropeanAM]

PCM strategies and exact time-outs vary from one calibration to another. It does sound as though yours is functioning as-designed now.