Merc 4.3 problem

[bago]

I have a problem with the engine of my boat that is a Mercruiser 4.3 with an EFI the serial # is OM 341529.When I reach over 2000 rpm the engine starts to run erraticly and after a while it stalls.When not in gear it reaches over 4400,but then again it stalls .On the other hand it idles perfectly .A friend of mine checked and didn`t like the spark- sad that it was too yellow.Meanwhile I put a new set of sparkplugs.Can someone point me in the direction that I must follow troubleshooting ?The engine has 130 hours and has been operated in salt water.Thank you!

 

[cooter2506]

Re: Merc 4.3 problem

have you changed your water seperator lately? When was the last time you did a complete tune up?

 

[bago]

Re: Merc 4.3 problem

Yes I did about 20 engine hours ago!

 

[Reel Poor]

Re: Merc 4.3 problem

It sounds like a fuel supply problem. Are both of your fuel pumps running? You may need to do a fuel pressure test to see if the fuel pumps are pumping like they should. With a vaccum gauge you can also check the suction side of the low pressure pump. Click here to see how to check the suction side of your fuel system.

 

[bago]

Re: Merc 4.3 problem

Thank you for the response.I`ll follow your directions tomorow.There is a chance to get a hold on a testing computer ,so I`m full of hope!