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2009 BF50 EFI rough idle/ stalling

P

Pointer18

New member
Hello,

Second season with this engine on a used boat I purchased last year. The idle has been getting rough, and it stalls often when shifting into neutral. The engine has 310 hours currently.

To date I have:
  • New racor
  • Checked/ cleaned idle air control valve
  • Inspected fuel system
  • New Plugs

I did run the engine directly off the six gallon tank for a period this spring w/ no Racor. Planning to check/ clean the fuel filter, and possibly do a VST service? May just service fuel system

Any help/ input would be appreciated

Jeff
 
You indicated that the idle is rough......does it run good at higher speeds?

Servicing the fuel system is good. Check the vapor separator vent for blockage.

Also, remove the map sensor and make sure that the hole is not plugged with debris....that is the hole in the sensor and the hole that in the manifold where it is mounted. Gently blow the sensor....do not use strong compressed air....the little compressed air can that you use to clean your computer is good.

If you can, measure the fuel pressure and see what it does as the engine is having issues. If it is, then checking operation of the fuel pressure regulator is in order.

Are you sure all the cylinders are firing? You can do a cylinder drop test a couple of ways. Either pull each spark plug wire off the plug, one at a time, and note is the engine rpms good down. If they don't then you have an issue with that cylinder. Could be fuel, spark, or compression. You could also do the same thing by disconnecting the injectors, one at a time.

Check compression. Should be approx 199 - 142 psi.

You should also check the valve clearances.

Mike
 
Thanks for the input Hondadude... will check some of the items you mentioned

Engine runs fine at all other speeds, and is smooth to WOT. Has really just been the idle getting rougher and stalling a bit if you go to neutral to quickly from forward or reverse speeds above idle. RPM seems very low idle as well
 
Your idle air control valve is right next to the MAP sensor Mike mentioned. Make sure that the mount gaskets and orifices for both components are clean and in good shape. That is IF the cylinder drop test produces no results.

Also, open your throttle and inspect the throttle plate and bore for any sign of dirt or grime. BUT, if you see any, DO NOT jump in and start cleaning. The throttle bore and the edge of the plate are coated with a Teflon like substance that can be easily damaged or wiped off. Most auto parts stores now sell special throttle body cleaner that comes with instructions on how to clean one.

Good luck
 
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