Help diagnose my problem

[RHuff]

 

I have a 2008 Triton that I just bought from a guy I know. His boat has sat for a couple of years with treated (Sta-bil) gas. I haven't gotten the title in yet so I haven't been able to register it yet. I've been trying to service it and tune it up myself before taking it out. My father and I are sharing this boat and we have tried running the motor a few times and here is what is happening. 

The engine is a Mercury 50 HP 2-Stroke. It has a hard time starting (has to be choked) at first. After we get it started it will run in idle for about 20-30 seconds before stalling. If you start it and put it into forward gear it immediately stalls. If you choke it during idle it stalls immediately. It idles and sputters a little for about 20 seconds then it idles down so low that it evenually shuts off. It almost acts like it is running out of gas but the primer bulb is priming up solid. You can smell gas pretty heavy but there is no apparant leaks. 

So far we have done the following:

Changed the lower unit lube.

Changed the batteries

Changed the spark plugs

Syphoned the old gas and filled it with new and added a bottle of seafoam. 

Checked the fuel filter and it is clear.

After each of these things the motor is idling better and smoother and quieter, but still stalls out after 30-45 seconds. I'm not really sure what else to do. My father thinks it may be a float in a carb but we are too afraid to attempt to take the carbs out to inspect them for fear of not being able to re-install them correctly. 

Anybody have any suggestions on what I need to do? The boat looks brand new and everything seems in great shape except for this one issue.

 

 

 

[Way2slow]

Sounds like the carbs need to be pulled and cleaned, but having sat for a couple of years,  there are several other things that probably should be done as well.  The whole fuel system needs to be gone through, probably needs new fuel lines also.  That's an eight year old motor, and with the gas we have now, fuel lines should be replaced after about five years.   If you are not familiar with rebuilding carbs and synchronizing  the linkages, even with a service manual, you might get in over your head.   Cleaning them takes being familiar with how they work and all the passages that need to be cleaned.  Might be better off paying the big bucks for a shop to do them. 

If you had taken the boat for a test drive before you bought it, you would have found this before it became yours and you could have had him get it running properly or reduce the price several hundred dollars to help offset what it's going to cost you. 

[RHuff]

I know I probably should have, but the boat was a steal for the price I paid, even with maybe having to have the carbs cleaned. It seems to me that its getting the needed fuel on start up. It starts at barely turning the key, its just like it starves itself out for gasoline after 30 seconds or so. If we manually work the throttle right next to the carbs it runs without stalling. It only stalls during idle and when using the shifter.

[webertime]

Get some Mercury Quicksilver Power Tune and give it a shot and see if that helps the carbs before tearing them out.

[Way2slow]

Not needing to take it for a test run because I got it at a steal is something I can say.  That's not a very wise decision for a novice that doesn't know them like the back of their hand.  By the time you get all the bills from getting everything in proper working order,  At approx. $100 per hour labor and the cost of parts today, after you pay the bills you might be finding out the repair shop got the steal. 

Giving it gas at the carb is not the same as giving it gas with the throttle.  The throttle is primarily just advancing the timing for the first part of it.  With many engines, it's not even moving the carb butterflies for the first 25% or so. 

Most motors that have sat for a couple of years, that were not properly prepped are going to have fuel problems.  Even going through all the right steps does not assure you won't. 

When I buy a used motor, especially one that has sat for a while, the first thing I do is rebuild the carbs and fuel pump (if rebuildable), purge the fuel system, check/replace all fuel lines that are dry/hard or soft and gummy,service the gear case and replace the water pump.   These are done before I even try to start it up. 

[WRB]

Change the gas line prime bulb, sounds like it may be your problem"

Tom

[JayKumar]

Read this, it may help:

 

[fishnkamp]

The poster above me has the right idea.  Before you do a lot remove the line going from your fuel tank to the primer ball.  Get a couple of gallons of fresh fuel. Add a 1/2 of a can of SeaFoam liquid (also comes in a spray can) fuel treatment to the gas can. run your water hose up to the engine with ear muffs and start the engine while running from the gas can.  Your engine is like my 75hp 2 stroke. I always need to go into fast idle and choke it a bit.  For my  throttle control box I push in the center of my throttle lever push up on the handle lever and push if forwards. other control boxes have a lever you pull up on to advance the idle up. Do not rev the engine high as it can hurt the motor while running on a garden hose.  i advance it till it runs about 1500 although you may need to push it a bit while the motor coughs and smokes.  Run a good bit of the fuel out of the can. Shut ti down and pour the rest into the gas tank. Add  the rest of the SeaFoam to the tank in fact I would run a second can also. There are some good videos on Youtube about this. Now the fuel lines should be replaced as the ethanol fuel is damaging the old style lines. Get the new line from your nearest dealer. I would also replace the fuel ball due to age. I would replace it with either a Merc of Johnson factory model. Some aftermarket ones are not working out well. I would do that first since you will need to disconnect the line anyway.

[Scott F]

After the motor stalls after 30 seconds, does it start right back up? What's the longest you've let it run? My older Mercury doesn't like to stay running after it has set for several months over the winter. It usually takes a few minutes for it to keep running without having to choke it. 

[Molay1292]

Probably not something you are not already doing, but those two stroke motors like to be ran in a level position, otherwise it can cause you some problems.

 

 

[BrianSnat]

If you think it might be the float in the carb, an old automobile trick was to tap the carb with a hammer while it is running. Good, hard taps, but not so hard as to break the thing. That can sometimes loosen up the float.

[RHuff]

3 hours ago, Scott F said:

After the motor stalls after 30 seconds, does it start right back up? What's the longest you've let it run? My older Mercury doesn't like to stay running after it has set for several months over the winter. It usually takes a few minutes for it to keep running without having to choke it. 

It will immediately start back up without choking it. It will idle with a slight sputter for about 20 or so seconds then slowly time down to the point that it stalls out. The bulb pumps firm and it appears and smells to be getting plenty of gas. I talked to a guy that lives in town that is an expert mechanic. He said he thinks its 99% a carb problem. He is going to stop by the house tomorrow to take a look to see what the deal is. He agreed that for the price I paid for the boat, that you probably couldn't get the motor. He said he will take the bowls out of the carbs and check the float and jets and that if it needs cleaned he will clean them real good and reassemble them for me. I'll keep the post updated on how it goes and what we figure out.

[crazyjoeclemens]

I'd say its definitely a carb problem.  Either you have a stuck float that's not allowing enough fuel through or you have a bad seal somewhere that's letting it suck some air.

[RHuff]

Update: My friend stopped by and took off the carberators. Not a trace of buildup on any internal part of any of the 3. The jets and floats look like they came out of the box. We took apart the fuel lines, still brand new. He assembled everything and had me start it. It popped and stalled again. He said "lemme try something." He reached in and grabbed a lever and cranked the RPM up to about 3500. It popped and cracked and smoked and leveled out just as smooth as silk. He said he burned all of the bad fluids out of the motor.

It ran smooth as could be and kicked in and out of gear perfectly without stalling. He said it's good to go.

He said the motor needs to be re-broke in and will improve the more its ran.

 

 

 

[fishnkamp]

That is great news.  As you run some new fuel through it always run StarTron to avoid fuel water issues. Also I would replace the fuel lines to the new ethanol resistant lines. I ddi not have a problem but replaced all the way from the tank to the fuel lift pump on my boat just to avoid a problem. Also I found Lowe failed to tighten a clamp at the fuel tank. Nice QC there. Glad I found it , it could have it to suck air or worse leak fuel into the bilge! Since it was behind aluminum panels I would have never seen it.

[RHuff]

Yeah that was a great find. I'm glad I have the piece of mind now knowing everything is in good shape. Still waiting on the titles to come in so I can register it asap.