Motor stalls - Fuel line

[Begynol]

Been having a problem with the motor.

It is a new Merc 9.9 outboard that comes with the Merc fuel line and tank.

This one here:
http://www.mercurymarine.com/parts-and-accessories/product-overview/portable-fuel-system/

My routine:
1. Open the vent on top of the cap. Been hot so a fair amount gas leaks out. Keep vent open.
2. Prime bulb
3. Half choke
4. Start engine - Usually 1-2 pulls starts and runs fine
5. Choke pushed to off


I will motor out of mooring field, then sail for a while.

When I want to return I restart motor, which starts with no problem.

After a period of time, usually minutes the motor stalls and wont restart.

I find the bulb has no fuel in it. It takes several minutes for the motor to restart.

I feel like I am following the instructions properly, but the motor seems to fail after about the same period of total time running since the first start of the day.

Of course this usually happens at the worst times - Coming up against swift current onto my mooring.

I am thinking fuel pressure. Maybe I shouldn't vent it?

Any thoughts?


Tom

 

[Tim R.]

This may sound ridiculous but I have seen a very similar issue when the hose is installed backwards. Make sure the arrow on the bulb points towards the engine.

 

[JK_Boston_Catalina310]

Something does seem off. Do you have the fuel demand valve in-line and on the tank (i.e. new mercury style tank with a vent on the cap?) If there is a vent on the tank and an in-line fuel demand valve that you linked to, that could be the problem. They could be working against each other and you are running on the initial prime until it runs our of fuel. Outboards can run on that initial prime for a longer time then you would think.

Other than the issue with loosing the prime at the bulb, it sounds like a carburetor issue. Or maybe a small hole/crack in the fuel line that is letting in air?

 

[RichH]

In addition to Tim's post, sometimes the 'quick connect' hoses will 'back off' their attachment nozzles after their initial connection. Just a little 'back off' of the quick connect will shut down the fuel flow. Next time this happens, tug onto either end of the hose to see if you still have complete contact of the connector(s); usually the faulty connection is at the remote tank connection.

add/edit - If this turns out to be the case, the solution is to use MUCH MORE force when attaching the connectors and 'aggressively' force them on once you pull the outer part of the connector back. Especially on the hose to tank connection once you FORCE the connection, simply pull on the hose to make sure you have a 'firm' connection; if the o-ring inside the quick connect is not firmly against the 'seat' of the tank nipple, it can easily allow air to enter the hose.

 

[Chris Patterson]

If it has a fuel pump, I would want to have a look at that.

 

[Winkfish]

Sounds like a leak somewhere between the tank and the motor. Check your fuel line connections, including, as Rich said, checking the quick-releases are on securely. Also, sometimes primer bulbs go bad, even new ones can be faulty.

 

[kloudie1]

No fuel in bulb, means bulb is collapsed or bulb is full of air?
Collapsed would mean tank is not venting or a restriction in the fuel pickup in the tank or the check valve not opening. (as in RichH's post) If the bulb is full of air, then there is an air leak between the inlet side of the bulb and the inlet tube. This could be the connector backing off enough to unseat the o-ring or the tank adapter fitting leaking at the threaded connection.. These notes assume a good fuel pump and fuel pump screen and good hoses inside the engine cowling. I have had a lot of trouble over the years with leaking quick connects on the fuel hoses, either at the tank, or the engine side.

 

[Begynol]

Thank you for all your replies, this was a big help.

The engine is really new - Like 2-4 hours on it.

The bulb is empty but not collapsed, so I am suspecting an air leak.

I am going to carefully inspect the line for proper connections, that the valve is in right directions. Will take all the connections off and re-seat them firmly.

Thank you

Tom

 

[JK_Boston_Catalina310]

Thank you for all your replies, this was a big help.

The engine is really new - Like 2-4 hours on it.

The bulb is empty but not collapsed, so I am suspecting an air leak.

I am going to carefully inspect the line for proper connections, that the valve is in right directions. Will take all the connections off and re-seat them firmly.

Thank you

Tom

A friend just had an issue where there were no hose clamps on the fittings. They felt tight but were letting in air. Adding a couple of small hose clamps solved his problem.