Mercury V6 200 Cough & sputter

[Mohsali]

Hi,my engine runs fine at full trottle for 10 minutes and it start to cough and sputtre and I reduce to 3000rpm still it occur. I cannot trottle up again as the engine would dies.Pls help.Its a Mercury V6 200HP 1985.

 

[schaiss]

Re: Mercury V6 200 Cough & sputter

Have you had the carberators off that engine for a cleaning? After buying a boat last year, I had the same problem with my V-6. I pulled the carbs off the engine and found 2 of the fuel jets (located at the bottom of each carb) completely plugged, and the other 4 main jets were very dirty. My V-6 is humming now!

 

[Mohsali]

Re: Mercury V6 200 Cough & sputter

Thanks for the reply. I've clean the cab, new spark plug, clean the tank, etc except new coil. More or less everthing is new. It run fine for about 10 minute or so, then the cough comes. When this happen,I try to trottle-up, it boggs down wanting to die.So I do about 3000rpm with the cough. Sometime the cough would die down and I could trottle-up to about 4500rpm. Maybe this will give a better picture of the problem

 

[gss036]

Re: Mercury V6 200 Cough & sputter

Do you have a fuel/water seperation filter? Should look like an oil filter or see thru type. It sounds like you have water in the filter or water in you fuel tank.

 

[Mohsali]

Re: Mercury V6 200 Cough & sputter

I 've empty the tank and put in new fuel. I went out this morning and about 10 minute at rpm 3500 it started to cough. But as I was not driving, it happen after a funny sound like the engine was klinking and the cough start. Put the trottle up to 4500rpm its ok for a while.My friend says it could be the electricial problem.Before the cough,funny sound something like the current short happen.He said try to change the coil and the cable.Any other ideas pls.

 

[randycc58]

Re: Mercury V6 200 Cough & sputter

posssible coil suspect. sounds like it may breaking down after heating up. I'd check spark after the engine starts to act up. any fouling of plugs?

 

[gss036]

Re: Mercury V6 200 Cough & sputter

Sounds like you are sitting at the dock with the motor running. You want to be careful running it up to high RPMs in nuetral, you need a load on the motor or you might blow the powerhead. I have always heard about 2000 RPM in nuetral.

 

[Mohsali]

Re: Mercury V6 200 Cough & sputter

Thanks for the reply. First the coil,how do I know that there is problem. I check the plug, seem ok (brown colour)How do I check the coil? When I pull the plug cable, it seem that one the the cable the connecting pin is damage. Maybe that's the cause.<br />Secondly about the rpm. Idle/nuetral the rpm is about 800rpm, so no problem there. It happen only after the engine has travel 10minute or so. Any ideas?

 

[KCLOST]

Re: Mercury V6 200 Cough & sputter

If it coughs/sputters, I would check the spark on every cylinder to see if you are losing spark on any... If you are, it's probably not fuel related....<br /><br />Get a spark gap tester, and check each by connecting it from the boot to the plug... Set the gap at 3/8" -1/2" and run the motor in neutral. Check one at a time, and always have each lead grounded that you are not testing. Determine which cylinder is loosing spark and then you can backtrack the problem, through the coils, switchbox, triggers etc.<br /><br />Let us know. A spark gap tester can be found at any auto parts store for around $10-$15...

 

[TwoBallScrewBall]

Re: Mercury V6 200 Cough & sputter

Had a smiliar problem on a 90 200, it was of all things the check ball in the fuel primer bulb. Bypass it or install a new one and see what happens. Apparently the check ball was sticking sometimes and would restrict the fuel flow.

 

[Mohsali]

Re: Mercury V6 200 Cough & sputter

Thank guys, When it first happen, I bypass the fuel primer bulb. Still no change to the problem. I'll try the spark gap testing which was recommended by KCLOST and back track the problem. Will tell you guys on the development later.