Won't stay running

[buckstalker3663]

Hey ya'll,
I have a Mercury Thunderbolt 50hp tiller handle that I just bought with a boat about a week ago and the guy I bought it from said he thought it may be a carb issue but I was wondering if I could get some more help. I just put a new gas tank, gas line with bulb on it. Cranked up fairly easily and ran fine for about 3-4 minutes and then it sounded like it was choking out and just died. I checked the bulb and it was a little less then half full so I pumped it back up and got going again but it continued to do the same thing. Any help would be great.

 

[orangeboat]

Re: Won't stay running

Just a thought, this was happening to me this weekend and here is what I figured out for mine. I'm no boat motor mechanic and I really don't know much about them so bear with me. The fuel connector on the motor where you plug in the hose has a pin just like on the tanks, when you plug the hose in the ball bearing inside the connector pushes the pin in on the other and allows the fuel to flow. Mine pin was bent over alittle so the bearing wasn't allowing the valve to open. After a few minutes of cursing I disconnected the hose, saw the bent pin, straightened it out and off I went with no more problems. Sometimes it can be the stupidest little things!

Thought I would add a little: Mine was doing the exact same thing, I thought my choke was sticking, I had all the same symptoms. I wonder how many of these stories are the same problem. The pin has to push the bearing in just like the bearing has to push the pin in. I wonder how many times one of them gets stuck just enough to inhibit fuel flow. Try pushing the pin in and see if it moves freely and the same with the bearing, make sure the pin is straight. If its bent even a little like mine was it would'nt open the bearing or the valve enough.

 

[mercmafia]

Re: Won't stay running

It reallt isnt that common of a problem for the plug to the bent and sounds a little clogged up.
Now with the original post, the engine stalling out like that is definatly a carb problem because we know you are getting fuel. What you need to do is take apart the whole carb and clean each part in it with carb and choke cleaner and a small needle to clean the needle and check all the seats. Also i would order a full gasket set and change those out.
Hope that helps.

 

[Wingedwheel]

Re: Won't stay running

If it ran fine and after it died the bulb was soft there was a flow problem. The reply about the pin in the fuel line connector was very interesting.

 

[buckstalker3663]

Re: Won't stay running

Thanks guys. I went to the auto parts store today and got some b-12 Chem tool to soak the carb in. Also, I noticed my gas tank was swollen because of the heat and I loosened the gas cap to release the pressure and it reminded me of a post I read where someone was having similar problem and all it was was they did not have thier air hole open on their gas tank and it wouldnt allow the engine to pull gas through the hose. Is there a way I can run my motor without having to launch my boat? After I clean the carb, I am gonna want to try it out but I don't want to go all the way to the lake to do this. Again thanks for the help.

 

[Jacket4life]

Re: Won't stay running

Yes. You can go to WalMart and buy a set of "muffs" (they look like earmuffs on a u-shaped piece of plastic or wire) that you can hook to a garden hose and run your motor. Costs about $7. Warning: you should not exceed 2500 RPM while doing this, your water pump will suck air, ruining the impeller and resulting in possible overheating.

I agree with the wheel: if after a short time running, the ball on the fuel line is soft again, you have a supply problem. The parts outside the motor are much more often the culprit than those inside, but a lot of ppl on here jump to the carb issue as soon as an OB starts not running perfectly. I would ensure that the lines, bulb, and tank are all good before I even touched the motor itself. And yes, if you were running with your vent closed, it could cause similar symptoms. That may be your only real problem.

Next issue, while you are at WalMart, buy a couple of quarts of Quicksilver lower unit lube. When you get home, drain the lower unit, then pull it and replace your impeller. The 2nd most common cause of failure in these motors is overheating. You just bought this boat, I know you'd hate to have to buy a motor.

You can do a search on here and get the steps on how to do it, but my reccomendation is to buy the Mercury service manual for your motor. It is well worth the investment. I bought mine off Ebay for $20.

Welcome to iboats, and best of luck!

 

[buckstalker3663]

Re: Won't stay running

Jacket, thanks for you advice. As far as the tank and lines go, they are brand new. here is some back story to help I hope. The guy I bought the boat and motor from is a motor cycle mechanis and did some tuning up on the motor. He said it had been running fine and then it started doing what I described. He said he figured it may be the carb since he had replaced everything else and he hadn't had time to check the carb yet. Well, a couple of days before I picked up the boat, he had taken the tank and fuel lines off of it and put it in his friends boat to go frogging. His friend had not been having any issue with his motor but not long into their trip his motor started doing the same thing. Well they took the tank and lines off and switched back to his friends original tank and lines and everything went to working fine for the rest of the trip. He said he thinks he may have had a cracked gas line or something like that. So I bought a new line and tank. I will try to get some "muffs" but how do I measure the rpms? I don't have any gauges. I will also look into purchasing a manual too.
The guy also put a new lower unit on the motor because the fin on the bottom had been broken off. But I will try to get this done and try it out and let you know. Thanks again for the advice.

 

[asm_]

Re: Won't stay running

Considering my pump bulb does soft after the motor has started, I would say that's not a good indication of problem.

Based on the information you have provided, I would guess it may be the fuel pump. In order to confirm the theory, you can try to give the bulb another squeeze after minute or two. If it stays running, I'll say your motor has lost it's ability to "suck" fuel into the carb.

B

 

[buckstalker3663]

Re: Won't stay running

So I took housing off my motor to look at my carburator to see if it looked fouled up and it looks pretty clean to me, but now I have a new problem. I had to remove the handle on my pull rope to get the top off the motor and when I did, I wasn't thinking and didn't put a knot in it to keep it from winding up which it did. So unbolted the housing from the top so I could get the rope out. Well, in the center of the housing is a bolt with a nut that has a star washer under it that I removed and can not get the nut restarted onto that bolt. The end of the bolt is cut inot a D shape and looks like it has been stripped. I don't know what it is called exactly or where to go to buy a new bolt and nut set. Please help.

 

[buckstalker3663]

Re: Won't stay running

ttt

 

[Wingedwheel]

Re: Won't stay running

Its called a sheave shaft and if you go to http:/www.boats.net they should have your parts.

 

[buckstalker3663]

Re: Won't stay running

Well, I found the nut and washer and got it put back together and took it out on the water yesterday. It toook several pulls to finally get started. It would have to be at full throttle in order to crank. Also, I could not get it to stay running without having to keep pumping the bulb. Then I heard what sounded like a chain or something skip a few times. I decided to turn around and head in when it just quit on me and would not crank anymore. I need some serious help amd I don't know enough about outboards to work on it myself. I am seriously thinking about taking it to the shop and having them give me a good assessment of what is going on. Or i may just sell it and try to find a smaller motor.