Motor troubleshooting

[HATH]

As luck would have it, while test driving my boat with a potential buyer, it decides to run poorly. At home it seemed to run great but the second we got on the lake it would barely start and once you pushed the throttle the motor would bog and die. The only way it would stay running is if I kept using the choke. I'm thinking it's a carb issue, especially since it has sat most of the summer. I went home and changed the plugs and that didn't change anything, and it has a new fuel filter. Any ideas? It's a Mariner 125 horse 2 stroke 4 cylinder outboard. Let me know what you think.
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[wiperhunter2]

Yea, if it ran good the last time you had it out before this problem started it is likely a carb issue. Do you run Sea-Foam or Stabli? I had the same issue on my last boat, it ended up being the carb and I had to have it overhauled. What year is it? Is it an oil injected motor?
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[HATH]

I had it out about a month ago and it ran just fine. I haven't ever ran any additives. It's a 98' motor and it is oil injected. I thought a good carb clean would do the trick (in this case I'll have to clean four single barrel carbs: (
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[DKStroutfitter]

Do as wiperhunter2 has suggested and run some seafoam through the engine. Not at home though. It will take a while to get enough of it through the engine to do any good.
You will also want to make sure that all of your fuel lines are in good repair and that you don't have any air leaks. Check for leaks at all the fuel line fittings.

The last suggestion that I have is to be sure that your fuel is fresh and clean with the proper amount of oil added.
Old fuel can cause a lot of problems.
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[HATH]

I appreciate it. I'll check that stuff out.
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[Kent]

[quote HATH]

As luck would have it, while test driving my boat with a potential buyer, it decides to run poorly.

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I'm sure that potential buyer is understanding and still may be interested (depending upon how much he finds out it will cost to make the interior and cover repairs).[]
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[HATH]

I'll keep the interested parties in the loop[] Here's the link to Penny's that Glen (Pikeman99) referred me to: [url "http://www.pennyseatcovers.com/"]http://www.pennyseatcovers.com/[/url]
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[up2nogood]

If you are having to use the choke sounds like you got some partially clogged jets, not getting enough fuel. Not a very difficult job to take apart ,and clean. That will probably fix your problem. I have done three different engines here lately, and it fixed them all ,no parts were needed. Youtube is a wonderful thing. Two generators ,and a four wheeler .
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[GEEZER]

First thing I'd do is be absolutely sure the fuel hose is good and air tight. If it admits even the slightest amount of air the engine will act as you describe. Next I'd check the fuel pump (s). When they start giving up it'll make the engine act up the same way. If the foregoing prove to be OK, then go after the carbs.
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[HATH]

How do you check for air leaks in the fuel lines? Also, couldn't I pump the priming bulb while the motor is running rough and if the motor smooths out it narrowed down my search to a air leak or fuel pump issue, eliminating the carbs as the issue? But if I pump the bulb and it remains running rough, I'd think the issue is the carb isn't getting the proper amount of fuel because it's plugged up.
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[Kent]

Tom, his bulb was still firm when the engine died, so I doubt that it is an air leak.
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[HATH]

How do you check for air leaks in the fuel lines?
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[wiperhunter2]

I'm not sure what Tom will tell you but one sign is that the carb will not stay primed and therefor you are having to constantly pressurize the system by pumping the bulb. When that happens you can use soapy water and some type of squeeze bottle to get the soapy water on the different line connections. After applying the soapy water look for bubbles, if you see some, that is a leaky connection.
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[HATH]

I tried to keep the motor running by pumping the bulb, but it didn't effect anything, and the bulb was firm when I was pumping it. The only way to keep the motor going is to choke it, but even then I have to feather it, choke it, turn choke off, choke it, turn choke off, etc.

On a side note I did see that there was a little milky color in the carbs, so I thought maybe there was water in the fuel, I put some Heat in it and some new gas, but that didn't effect how it runs.
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[HATH]

Just wanted to update everyone in case someone else has the same problems as me. I rebuilt the fuel pump, put Heet in the tank, checked the fuel sending unit, replaced the fuel filter, took all the carbs off and cleaned them, checked for leaks in the hoses, etc. Long story short the problem was the primer bulb. I replaced that and now we're good as gold. I didn't ever suspect it because I had replaced it a year or two ago, I guess it's something that needs to be replaced annually? Hope this helps someone.
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[wiperhunter2]

Thanks for the update Hath, glad to hear you got it figured out. Just because the primer bulb is the easiest and usually the one of the cheapest to replace, it is always a good place to start. It does not hurt to replace them ever few years but in general buying a good quality bulb is the key. Some times you just never know how long they have been sitting around when you buy one but getting to know you local marine dealer is a good idea because they can usually tell you how long the bulbs they have have been sitting around, where as buying on from say WalMart, you just never know.
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[dtayboyz]

Glad you found the problem, fuel is nasty stuff specially now with ethanol, it eats rubber and such.
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