MERC 3.4L SPARK COMES & GO...

[CARLOS]

MY 3.4L ENGINE START OK, BUT I FELT LOST OF POWER LAST WEEK END RUNNING.<br />AFTER CHECKING, I FOUND SPARK PLUG #1 IS NOT WORKING...I MEAN, THE SPARK IS COMPLETE CLEAN...NO CARBON IN IT.<br />I REMOVE THE SPARK AND START ENGINE AND FOUND SPARK (RED COLOR)...I CLEAN THE CARBURATOR AND THE CYLINDER #1 STILL NOT WORKING.<br />I READ COMPRESSION AND FOUND 112 PSI.<br />MY QUESTIONS:<br />1-MAYBE THE SPARK IS NOT ENOUGH POWER TO GET FIRE INTO THE CYLINDER?<br />2-CAN I INSTALL IGNITION COIL FROM THE 200 MERC, AS A TEST FROM PARTS FROM OTHER ENGINE?<br />3-WHAT ANY OTHER THING I MUST TO CHECK?<br />I´M VERY AMAZING WITH THIS ENGINE...ALL THE WEEK END I WAS RUNNING WITH ONLY 5 CYLINDERS WORKING...FULL OF GASOLINE AND 7 PERSONS...<br />THANKS IN ADVANCE FOR YOUR ANSWERS<br /><br />CARLOS SCHEMEL<br />VENEZUELA

 

[CARLOS]

Re: MERC 3.4L SPARK COMES & GO...

ANY REPLY FOR ME...

 

[crazy charlie]

Re: MERC 3.4L SPARK COMES & GO...

Check my last post it may help you.it is at the bottom of this page or it may have moved to the next page "86 175 merc lost spark" Charlie

 

[CARLOS]

Re: MERC 3.4L SPARK COMES & GO...

THANKS CRAZY CHARLY,<br /><br />I´M WORRIED ABOUT A WEAK SPARK, BECAUSE THE COLOR IS LIGHT RED, NOT BLUE..., AND MAYBE THE SPARK IS NOT ENOUGHT TO FIRE THE MIXTURE.<br />ANYWAY, TONITE, I´LL CHECK THE SPARKS AGAIN IN ORDER TO COMPARE BETWEEN CYLINDERS.<br />THIS KIND OF ENGINE IS DIFFICULT TO TEST THE CYLINDERS BY KILLING ONE BY ONE, BECAUSE IF YOU DISCONECT ONE SPARK PLUG WIRE , THE RPM´S DON´T DROP...EITHER IF YOU DISCONECT 2 WIRES...THE IDLE KEEP AT 1000RPM...ITS CRAZY...ENGINE...<br />TOMORROW I´LL POST RESULTS.<br />THANKS<br />CARLOS

 

[Kenny Bush]

Re: MERC 3.4L SPARK COMES & GO...

Hey Carlos, Yesssssss you can swap that coil out off that 200. I have replaced several of those coils out over all the years. I agree with you about them running just fine on 5 cylinders. It is amazing. Also you said that you were idling at 1000 RPMs. I have got mine to idle down to 550 to 600 rpms. Book says 650 to 750. Also your compression seem a little low. My lowest is 120 pounds (Warmed Up). Are you decarbing that motor regularly?

 

[CARLOS]

Re: MERC 3.4L SPARK COMES & GO...

HELLO BUSHCAT, THANKS FOR YOUR REPLY,<br /><br />YESTERDAY AT NIGHT, I WAS CHECKING FOR THE CYLINDER #1 IGNITION COIL, AND FOUND A LOT OF GREASE (BEARING GREASE) BETWEEN THE SPARK CABLE AND THE COIL...(MAYBE MECHANIC INTRODUCE GREASE INSIDE IN ORDER TO PREVENT CORROSION...)<br />SO AFTER CLEANING I STARTED THE ENGINE WITH OUT SPARK PLUG AND DID SEE THE SPARK FOR FEW SECONDS...MAYBE I FIXED BUT NOW I HAVE TO TEST RUNNING...YOU NOW, IT IS DIFFICULT TO CONFIRM AT IDLE SPEED IF ALL CYLINDERS ARE WORKING PROPERLY.<br />NEXT TEST IS TO SEE IF THE TEMP GAUGE IS INCREASING TEMP...AS YOU KNOW, THE TEMP SENSOR IS CLOSER TO THE CYLINDER #1(TOP LEFT, LOOKING FROM THE FRT OF THE BOAT)<br />REGARDING YOUR QUESTION FOR DECARB, I NEVER PERFORMED, MAYBE BECAUSE IN VENEZUELA IT IS DIFFICULT TO FIND THE DECARB PRODUCT...THE DIFFICULT ECONOMICAL IN OUR COUNTRY DO NOT ALLOW US TO BRING IMPORTED PRODUCTS FROM OTHER COUNTRIES...ANYWAY, MY ENGINE HAS LESS THAN 150 HRS OF USE SINCE REBUILT...SOON I WILL TRY TO ASK IN OTHER SHOPS FOR DECARB PRODUCT...<br />IF ANY OTHER COMMENT, PLEASE DO NOT HESITATE TO REPLY ME<br />THANKS AGAIN<br /><br />CARLOS

 

[CARLOS]

Re: MERC 3.4L SPARK COMES & GO...

AFTER SOME TESTS, THE PROBLEM STILL HAPPEN IN ENGINE.THE CYLINDER #1 IS NOT WORKING...SPARK PLUG IS COMPLETELLY CLEAN....LIKE NEW...<br />TODAY, I REMOVED THE IGNITION COIL (#1 & #2 CYLINDER TOGETHER)AND FOUND A LITTLE OF WATER (SMALL DROPS) BETWEEN THE INSIDE CONTACT OF THE COIL, A (TO NEGATIVE).<br />AFTER CLEANING, I STARTED THE ENGINE AGAIN WITH THE SPARK PLUG OUTSIDE OF HEAD, AND SEE THE SPARK LIKE COMING-GOING, I MIND, SPARKING FOR SOME SECONDS AND THEN DISSAPPEAR FOR 2 SECONDS AND THEN APPEAR AGAIN...ALSO AFTER THE FIRST 3-4 SECONDS OF ENGINE STARTED THE SPARK BEGUN TO BE WEAK...IT IS SOME ABNORMAL CONDITION...<br />CAN IT BE THE IGNITION COIL DEFECTIVE?<br />DOES ANYBODY HAS THE RESISTANCE VALUE OF IGNITION COIL? IN VENEZUELA IT´S DIFFICULT TO FIND THE SHOP MANUAL.<br />CAN IT BE THE SWITCH BOX DEFECTIVE? HOW CAN I TEST THE SWITCH BOX...<br />OF COURSE I´M SURE THAT CARBURATOR IS COMPLETELLY CLEAN...<br />SOME HELP WILL BE APPRECIATED.<br />BUSHCAT, PLEASE REPLY ME AGAIN....<br /><br />THANKS IN ADVANCE<br /><br />CARLOS

 

[Kenny Bush]

Re: MERC 3.4L SPARK COMES & GO...

Yes Carlos it sounds like your coil is dropping. I will look in my Merc manual and see what the specs are for ohming out a coil. Did you swap that coil out off a smaller V6? They are the same. I had the same problem several years ago and I was pretty sure it was the coil. I ended up changing trigger plate and stator too. I do not know if they were the problem, but I have fixed that problem by just changing out the coil.

 

[CARLOS]

Re: MERC 3.4L SPARK COMES & GO...

THANKS BUSHCAT,<br /><br />FINALY I REPLACED THE IGNITION COIL AND THE PROBLEM WAS SOLVED. FOR YOUR REFERENCE, I INSTALLED THE SAME IGNITION COIL FROM A 50 HP MERCURY...IS EXACTLY THE SAME...<br />MY IMPRESION, THE MERCURY´S IGNITION COIL IS VERY DELICATED...MAYBE OMC´S HAS BETTER DESIGN AND PROTECTION...<br />THANKS AGAIN<br /><br />BUSHCAT: HAVE YOU ANY E-MAIL ADDRESS...<br />MINE IS: carlos.schemel@mmcautomotriz.com<br />I CAN SEND SOME PICTURES FROM MY ENGINE&BOAT IN VENEZUELA.<br />REGARDS