Outboard flooding issues

Jaymer

Recruit
Joined
Aug 10, 2023
Messages
5
Hello

1988 Mercury 2 Stroke Oil Injected 3 Cylinder Outboard
SN - B302789

I dont know much about these so ill try to make as much sense as i can in regard to the issue im having.

I seem to be having a flooding issue, and i think its coming from the pulse hose that runs from the face of the fuel pump directly to the crankcase. Is it possible for fuel to reach the crankcase from that line? If i pull the line from the crankcase and pump the primer bulb it spews gas out of the pulse hose and very little seems to get to the fuel filter, then up to the carbs. The primer bulb does not seem to stiffen up very much either if i keep pumping it. If i pinch that line (pulse hose) and run the motor it runs great, and the primer bulb will also get hard in this scenario. The second I let off, the motor stalls out.

I rebuilt the carbs. Tore them down, ran them through an ultrasonic cleaner, checked the float needle and bowl and those are good (air tested them to make sure the float needle was sealing)

I attached a screenshot of the fuel pump diagram and pointed out where the fuel is spewing from if i disconnect it from the crank case and pump the bulb. I cant seem to find any info saying if this is normal or not. From my understanding this is only supposed to be a vacum line that pulses a diaphragm in the pump. I should also mention that gas comes out of that line when i try turning the motor over.

In addition to the flooding, its also just dumping gas like crazy. Last time I ran the boat it dumped 6 gallons in less than an hour run time. I ended up needing a tow off the lake. Gas seemed to have just flooded into the crank case and dumped out of the exhaust. Could barely keep in running that day.

Hope someone is able to clear this up or at least point me in the right direction. My guess is its a bad fuel pump? Thanks for your time!
 

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jimmbo

Supreme Mariner
Joined
May 24, 2004
Messages
13,808
Welcome to iboats

If the Diaphragm is ruptured, gas can end up in the Crankcase, making that cylinder run rich. Hopefully what Fuel was getting to the Crankcase via the Pulse Hose, was already mixed with Oil, if not... Do a compression check
 

Jaymer

Recruit
Joined
Aug 10, 2023
Messages
5
Hello, Jimmbo. Thank you for your reply.

My guess would be that it was not mixed or at least very rich. However, i am getting white smoke which indicates I'm burning oil, right? I will buy a diaphragm kit for the fuel pump and first and see if that does it.

And just so im getting this right. Fuel is NOT supposed to spew from the pulse line into the crank case when priming, correct?
 

Jaymer

Recruit
Joined
Aug 10, 2023
Messages
5
Thank you. I ordered a diaphragm kit and compression tester and it will be here tomorrow. Hope this fixes it!
 

Jaymer

Recruit
Joined
Aug 10, 2023
Messages
5
Boost diaphragm had two tears in it so I replaced those and the gaskets. Hoping this was the issue. I’ll be putting it back on in a few and hopefully down to the lake tomorrow morning.
 
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