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Charles, Marine Mechanic
Category: Boat
Satisfied Customers: 3399
Experience:  US Navy (Ret) Certified Mercury Marine Tech with over a decade of repair experience.
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I have a 2007 efi 4 stroke 90 hp outboard. bottom cylinder

Customer Question

i have a 2007 efi 4 stroke 90 hp outboard. bottom cylinder keeps filling with fuel, wonder if it could just be a spark plug issue. i have pulled them and they seem to look ok, just trying to figure this out. injectors are working corectly.
Submitted: 8 months ago.
Category: Boat
Customer: replied 8 months ago.
mercury serial number 1B523321
Customer: replied 8 months ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  Jason replied 8 months ago.

Hello my name is ***** ***** am I speaking with?

When you say it's filling with fuel, is the engine actually locking up due to a hydrolocked cylinder that is full of fuel?

Customer: replied 8 months ago.
my name is ***** ***** no its not hydro locking, it would eventually if i kept cranking. when i pull the plugs and crank it. it sprays a bunch of fuel out of the bottom cylinder and some excess out of the 2nd from bottom. i unplug the injectors for this aswell. i pulled the fuel rail yesterday and zip tied the injectors in it and cranked the engine to watch the injectors cycle and they all appear to be functioning the same. got it to fire up yesterday after leaving the plugs out over night allowing the cylinders to air dry. ive ordered plugs as no autoparts store carries them.
Customer: replied 8 months ago.
just trying to understand why it is all accumulating in the bottom cylinders. im not use to working on boats. im sure there is an explanation, i just dont get it.
Customer: replied 8 months ago.
please give me a call at(###) ###-#### ***** back outside to pull the plugs again.
Expert:  Jason replied 8 months ago.

Hi Blake,

Is there a story to this engine? When did it last start correctly? Have you ever personally seen it start correctly?

Customer: replied 8 months ago.
it sat for 2 years, i bought it from a friend who said it ran fine before hand. when it started yesterday it ran great but i just had earmuffs on it so i only let it run for like 3 minutes. upon trying to start it again before heading to the lake today it was flooded. pulled the plugs to confirm and sure enough it was overloaded with fuel on the bottom 2.
Expert:  Jason replied 8 months ago.

Is there a primer bulb installed anyplace on the boat between the fuel tank and engine?

Expert:  Jason replied 8 months ago.

Also, I did try to accept your request for phone service. The system says your payment did not go through to authorize the phone call. Did you want to get that squared away with customer service, or did you want to stay online?

Expert:  Jason replied 8 months ago.

Are you still with me Blake?

Customer: replied 8 months ago.
installed all new fuel lines and there is a bulb which is tight. it keeps overloading on fuel. really dont get it. one of the injectors must be getting stuck open, i mixed up to injectors to see if the fuel overload switches cylinders.
Expert:  Jason replied 8 months ago.

There is not supposed to be a bulb on that engine, and that might be causing the issue. Remote it and retest, and let me know if you stop getting fuel in the cylinders.

Customer: replied 8 months ago.
still doing the same thing.
Customer: replied 8 months ago.
i moved the fuel injectors and the the spark plugs around this time to see if the problem switched cylinders it did not. another thing i notice, there is some fuel driping out of the exhaust/prop shortly after cranking. just dont understand why or how it ran yesterday. now all of the sudden it is flooding out. headed into downtown to pick up a set of plugs. found some.
Expert:  Jason replied 8 months ago.

There is a vacuum line that runs between the fuel supply module and the intake manifold. Remove that line, cycle the key from OFF to RUN a few times. Is there any fuel coming out of that line or is it dry?

Customer: replied 8 months ago.
they are dry but i dont have the air cleaner on it right now which i see now one of the lines that hooks up to air cleaner looks similar to a fuel presure regulator, could that be the issue?
Expert:  Jason replied 8 months ago.

No that wouldn't be it. The next step is to do a compression test and see if the cylinders have any compression or not. Do that next and let me know what you get for results.

Customer: replied 8 months ago.
compression is good.
Expert:  Jason replied 8 months ago.

What are the actual numbers?

Customer: replied 8 months ago.
my gauge is messed up but they all showed right around 85 which is around 120 or so on my jacked up guage.
for some reason it is overloading with fuel. it has nothing to do with the rotating assembly. has to be somthing with the fuel system or spark.
Expert:  Charles replied 8 months ago.

Hello, my name is***** will assist you.

Do you still require assistance on the engine?

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