15hp 4-stroke Mercury won't start! Need help or ideas!

[jakedg23]

I have a 2003 Mercury 4 stroke that has always run great. No electric start just pull cord. I had it running in the garage before we left for the lake and nothing seemed wrong. I got on the lake and after a while it started chugging and then died while driving about half throttle. Then it wouldn't fire unless I had it on full choke but then it would quickly die again. It woudn't even fire up without choking. The only new thing I've done this year is replace the fuel line and end clips for gas tank and motor. Seems like an obvious fuel problem? Here is what I've done to try and fix:

Gas line seems fine, gas is definitely getting to the carburetor.
Carburetor is as clean as a whistle, has all new gaskets, o rings, float, needle etc.
New gas filter installed. New spark plugs, getting a very good spark on both.

Any clues as to what to look at next?

 

[ONERCBOATER]

Re: 15hp 4-stroke Mercury won't start! Need help or ideas!

fuel pump? reclean carb very very carefully paying close attention to the lil holes (jets)?
do you have spark? it sounds like you would have already checked this but have to ask.

Sean

 

[jakedg23]

Re: 15hp 4-stroke Mercury won't start! Need help or ideas!

Thanks for the reply,
Yes we have good spark and I just maticulously cleaned the carb. When I put everything back together it still won't fire up. I just don't feel there is much more to it, but obviously I'm missing something important. Any thoughts are welcome.

 

[Maxz695]

Re: 15hp 4-stroke Mercury won't start! Need help or ideas!

yea sounds like the fuel pump

 

[rovmike]

Re: 15hp 4-stroke Mercury won't start! Need help or ideas!

Get a sprat bottle fill it with gas. Spay a little in the mouth of the carbs. Crank engine if it tries to run then dies you are not getting gas to the cylinders. From there unplug the fuel line from the backside fuel pump. Crank ingine over and see if you are pumping fuel. If not unplug othe side of fuel pump and squeze bulb. If you can push fuel through bulb easy the fuel pump is bad. If you can't get fuel though the bulb easy you have a bad bulb or a tank restriction. Make sure you did not put the fuel filter in backwards!

 

[dingdongs]

Re: 15hp 4-stroke Mercury won't start! Need help or ideas!

do we assime that you've released the tank valve so you don't have a vaccuum from stopping fuel getting to the carb.

 

[Star]

Re: 15hp 4-stroke Mercury won't start! Need help or ideas!

Dear Petty O,
I own a 05 15hp 4 stroke Mercury. I have forgotten to open the tank vent. It will suck the sides of the tank in an inch and just keep on running! I belive his float needle is stuck. If the prime bulb pumps up hard it is.

 

[jeffersondodson561]

Re: 15hp 4-stroke Mercury won't start! Need help or ideas!

Next time you try to start it, after all of you pulls, pull the spark plugs and see if the electrode is wet. If it is you know gas is getting to the combustion chamber.