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Dominick
Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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2008 50 hp 2 stroke outboard. the motor seems to loose prime

Customer Question

2008 50 hp 2 stroke outboard. the motor seems to loose prime if it is turned off for more that 5 minutes. It will start but takes about 10 minutes of constant restarting before it will throttle up without stalling if you put it in gear gear. As soon as you throttle up in gear at all it will stall. I have changed gas lines, fittings, and that pump in the gas line. I use premium gas ,have new spark plugs in it. Only thing I can see that may be part of the problem is the connector on the gas line to the motor doesn't seem to fit real tight. Any help would appreciated.
Submitted: 11 months ago.
Category: Boat
Expert:  Charles replied 11 months ago.

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

Would you please post the serial number of the engine?

Does the connector to the engine leak fuel?

Has the engine been siting?

Customer: replied 11 months ago.
it is a 2007 Mercury 50hp outboard 2 cycle model 50ELPTO 5500Can't see any leakage at all. the engine sits inside my garage each winter but this has been going on now a couple of summers.
Expert:  Charles replied 11 months ago.

So really you are having a hard time starting when the engine is warm?

Customer: replied 11 months ago.
it will start fairly easy if it is warm but wont stay running if you put it in gear until it has been running maybe 10 minutes or longer.
Customer: replied 11 months ago.
it acts like it looses prime until it has been running a few minutes.
Expert:  Charles replied 11 months ago.

Ok, when you last changed the plugs, how did the tops look.

I tried to accept your request, but the system would not let it go through.

Customer: replied 11 months ago.
plugs looked fine but I put in new ones anyway. fuel is always premium grade and no alcohol gas.
Customer: replied 11 months ago.
I gave my new credit card number to this site a few minutes ago. old credit card account got changed when my car got broke into last year.
Expert:  Charles replied 11 months ago.

Sorry to hear about that.

Have you changed the fuel filter, and what brand is the primer bulb?

When you replaced the old fuel line, was the inside of it falling apart?

Customer: replied 11 months ago.
from a cold start when first on the water ,after it warms up a couple of minutes I can idle out fine and throttle up fine and run at all different speeds fine. If I turn it off and sit to fish, of something for over 10 minutes, it takes about 10 minutes of continual restarting before it will throttle up once in gear.
Customer: replied 11 months ago.
I looked at the fuel line and couldn't see any problems and I now use high pressure fuel line I buy at NAPA instead of the generic fuel lines but this has not solved the problem.
Customer: replied 11 months ago.
primer bulb I just bought at a sporting goods place. no idea what brand it is.
Expert:  Charles replied 11 months ago.

Have you opened and inspected the main fuel pump on the engine?

Customer: replied 11 months ago.
no.
Customer: replied 11 months ago.
just got the serial number 1B527228
Expert:  Charles replied 11 months ago.

This is the diagram of the fuel pump. 2 of the bolts hold it to the block, the other two hold it together. Can you open it and isnpect the diaphragms and the check valves?

http://www.boats.net/parts/search/Merc2/Mercury/50%20%283%20CYL.%29/0T980000%20THRU%200T999999/Fuel%20Pump%28Electric%29/parts.html

Customer: replied 11 months ago.
you your saying the problem is probably the fuel pump ?
Expert:  Charles replied 11 months ago.

It is possibly the fuel pump leaking back or a sticking or hung check valve. We don't know until you eliminate it.

Customer: replied 11 months ago.
wont be able to get to the boat until tomorrow but I have rebuilt tractor carbs, /fuel pumps etc. shouldn't be much worse than that. is there anything else left besides the fuel pump that might be a cause? I understand the fuel pump possibility.
Expert:  Charles replied 11 months ago.

While you are there, do a compression test as well. Any less that 90 PSI, the engine will have all sorts of issues.

Customer: replied 11 months ago.
ok, if it gets rather complicated, I'll buy a new 4cycle motor and be done with it. I don't have 100 hours on the motor as it is.I'm leaning toward it being something simple. like the fuel pump. I just haven't gone that deep. It runs excellent once it gets going at any rpm.
Expert:  Charles replied 11 months ago.

There is not much too complex on this engine. I can guide through anything on it.

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