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Merc 2002 XR6 150, 2 and 5 cylinders fouling plugs

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procrafter

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I have a 2002 merc XR6 150, the 2 and 5 cylinders are fouling those plugs. it seems like this happen more when the motor has warmed up, here are things I have checked already, compression is good, fuel and oil pumps have been rebuilt, all new hoses, recirculate valves on those cylinders are good, coils are good, replaced plugs. Any suggestions on fixing this problem will be greatly appreciated.
Thanks
Ken
 
The only thing in common with those cylinders are the recirc lines and trigger. Index the flywheel and check timing on those 2 cylinders as trigger could be acting goofy or if it has the stabilizer/spark module disconnect it and retest.
 
Just something else to cross of the list, check the exhaust tuner hasnt fallen off.
Very common on the 2001 to 2008 2.5 motors and causes it to run rich and foul plugs in the low to midrange.
 
Just something else to cross of the list, check the exhaust tuner hasnt fallen off.
Very common on the 2001 to 2008 2.5 motors and causes it to run rich and foul plugs in the low to midrange.
Click to expand...
I have fixed several that have fell off but customers never complained or engine showed signs of running rich, just some loss of hole shot torque and some top end rpm..
 
Thank you both for your input. I'm taking it in to my mech. on wed. 1 other thing that I thought of, the motor seems to run better after I've stopped if I keep the motor up like to as far as you could bring it up when your running, it also seems to smoke less when starting also. any thoughts on that ? Thanks again
 
Does sound like blocked recirculation lines. But don't rule out the dropped tuner, mine fouled plugs continuously before we found it. Now I change plugs once a year / 100hrs with no problems. Might be different with the EFI compared to the carbed motor. (mines EFI)
 
Thanks Mag, I didn't ck the lines themselves, but ck. the valves and they are working as they should. I don't know how to go about ck. the tuner, but going into my mech. on wed. I bought this boat and motor new, and have changed the plugs every yr. with no exception.
 
I went to the lake today, and ran the heck out of it and it seemed to run good after a bit. I'm thinking that I may have blown out most of what was causing the problem, it's still not right though. I will relay the info to my mech. when I bring it in to him on Wed. Thanks
 
My money is on the dropped exhaust tuner. Mine would run ok if I ran it hard for the first few minutes. If I tried to plane off slow the plugs would foul most the time.
 
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