have to prime to keep motor running

[lanezupkov]

O.K. I Have a 86 mercury 115 hp mercury outboard. I put a brand new tempo 12 gal tank in the boat. I prime the bulb until it's hard the motor runs real good. Then it runs out of gas and stalls. I prime the bulb until it's hard and the same thing happens again. I did this for an hour and a half. I have kept the vent closed on the tank the entire time. Is this correct? Is the fuel pump bad? Is the tank bad? I installed a brass fitting on the tempo tank, should the fitting be one of mercury's? I have read some of the other post but now I'm really confused.

 

[Motor Boater Bill]

Re: have to prime to keep motor running

Open the tank vent.

 

[lanezupkov]

Re: have to prime to keep motor running

Should I open the tank vent before priming and starting or after it's running

 

[timmathis]

Re: have to prime to keep motor running

Vent must be open at all times. Starting, priming and running. You close it only when it is in storage.

 

[lanezupkov]

Re: have to prime to keep motor running

Would that cause the problem of the motor stalling and needing to be primed again? I will take it down to the lake in the morning and try it with the vent open. Thanks.

 

[tashasdaddy]

Re: have to prime to keep motor running

yes, fuel starvation, can't suck gas out of tank, with vent closed.

 

[Motor Boater Bill]

Re: have to prime to keep motor running

The primer bulb and your fist produce much more pumping power than the fuel pump on your motor, so when you "prime again" you are overcoming the vacuum you have created in the fule tank by leaving the vent closed. Please let us know if this solves your problem. Leaving the vent closed is like leaving the plug out when you launch. Everybody gets to learn it the hard way, hopefully just once!

 

[lanezupkov]

Re: have to prime to keep motor running

Well leaving the vent open let the motor run a little longer but it still runs out of gas. There is a half a tank of gas. I'm thinking the fuel pump is bad. To bad there is no parts stores open this sunday.

 

[timmathis]

Re: have to prime to keep motor running

You are right. It looks like you have a fuel pump problem. It should be a simple fix for you.<br />Cool looks like you will be ready for next weekend. Good luck, Tim

 

[nos1013]

Re: have to prime to keep motor running

Did you install a new quick disconnect on the new tank? I've also heard the cheap aftermarket disconnects can be a headache.

 

[Chunder06]

Re: have to prime to keep motor running

I'll put my money on no parts required, just crap holding the check valves open.

 

[tashasdaddy]

Re: have to prime to keep motor running

how old is the gas you are using.

 

[Snipe]

Re: have to prime to keep motor running

Had this same problem, couldn't put my finger on it. I noticed that the primer bulb check valve was rattling around in the bulb. Replaced the bulb, problem solved.<br />Snipe

 

[lanezupkov]

Re: have to prime to keep motor running

It's new gas, new bulb, new gas line to the motor, and new quick disconnects on the motor and tank. I did get the rebuild kit for the fuel pump, and the rebuild kit for the middle carb. The float was stuck open. Thanks for all the input. I should be able to try it out on saturday.

 

[lanezupkov]

Re: have to prime to keep motor running

Thanks for all the help!!! It was the fuel pump. The diaphram had a crack in it, from dry wrought. The check valves could of had dirt in them or they too suffered from dry wrought. I'm sure i'll be back with more questions. This was the first day on the water in my boat.

 

[timmathis]

Re: have to prime to keep motor running

Ge her done!!!