Spark loss AGAIN !!!

[Javelin 353]

1991 70 hp Johnson While using boat last was running and rpm died down to 2500, stopped restarted, same thing , stopped disconnected temp sensor restarted same thing, while limping back at 2500 rpm motor took off then slowed down again the took off again and ran fine rest of day<br /><br />Compression 115 all 3<br />Coils and powerpack new 10/05<br />cleaned all battery connections and coil grounds<br />no visible goo coming from under the fly wheel<br />I am postive this is spark because when at 2500 i hit the choke and the motor died<br />new fuel filter and plugs(champion qljc77 .030)<br /><br />Maybe powerpack again???<br />Lost??

 

[tashasdaddy]

Re: Spark loss AGAIN !!!

deleted, miss read post. sorry

 

[DHPMARINE]

Re: Spark loss AGAIN !!!

When the motor cuts back to 2500 RPM,can you slow it down to an idle? (without stalling)? If so you probably are not loosing spark.Most 3 cylinder engines won't run on 2 or less cylinders.<br /><br />DHP

 

[Javelin 353]

Re: Spark loss AGAIN !!!

will idle but, roughly?

 

[Walker]

Re: Spark loss AGAIN !!!

I am postive this is spark because when at 2500 i hit the choke and the motor died<br />new fuel filter and plugs(champion qljc77 .030

You need to do a definitive spark test while its acting up. I'd say you have a fuel problem, most likely one or more cruddy carbs

 

[reeldutch]

Re: Spark loss AGAIN !!!

run the motor till the problem happens again.<br /><br />with motor running pull the plugs till you find the plug that does not affect the motor.<br />this cylinder is not making power.<br />could be no spark or gas related problem.<br /><br />take a good look at the sparkplug and see if its bonedry or soaking wet.<br /><br />bonedry - no fuel<br /><br />soaking wet - no spark<br /><br />check for spark 7/16 jump<br /><br />if there is no fuel be very carefull because you will have no lube either.<br /><br />let us know<br /><br />good luck<br /><br />RD

 

[dc in ms]

Re: Spark loss AGAIN !!!

Consider mid range or top end jets in carb. The carb jet suppling fuel at this particular speed may be causing the problem. stopping up...

 

[Javelin 353]

Re: Spark loss AGAIN !!!

I ran boat today all was fine, lake was very very rough so only went up to 4500 rpm. when do the mid range and top end jets kick in in terms of rpm's. The only time this problem happens is at full throttle???

 

[Javelin 353]

Re: Spark loss AGAIN !!!

Update!!! Out today lost rpms NO SPARK on middle cylinder limped back to ramp engine sped up once for a very short time then slowed still NO SPark on Middle cylinder, maybe PowerPack???

 

[rickdb1boat]

Re: Spark loss AGAIN !!!

Swap coils and see if the problem follows...

 

[Javelin 353]

Re: Spark loss AGAIN !!!

Checked spark today all 3 very strong 1/2 " Blue <br />What now?

 

[rickdb1boat]

Re: Spark loss AGAIN !!!

Try heating the powerpack up with a hair dryer with the motor running on the muffs and see if it loses spark. Something is failing when it gets hot. Might try the coil, too...

 

[Javelin 353]

Re: Spark loss AGAIN !!!

just ordered a new sierra pack $85 shipped OEM pack $150 at dealer I'll see what happens with new sierra to much price differences to get OEM this time.<br /><br />Do you think I need to pull the flywheel and check strator?

 

[Javelin 353]

Re: Spark loss AGAIN !!!

tried hair dryer trick before with no sucess?

 

[Per]

Re: Spark loss AGAIN !!!

This might seem silly... <br />Your motor should be equipped with a feature known as S.L.O.W. mode. The S.L.O.W. mode will bring your RPMs down to 2500 when the engine temp rises above 240 degree F.<br />I'm not saying that your engine is overheating, but it might think so and act up you.<br />I have the test procedure in Swedish but it would take me a day to translate it, maybe some English speaking person with the workshop manual could chime in!?<br /><br />Good luck!<br />Ps: Please don't tell any Merc owners that there is something called S.L.O.W. mode on the OMC engines, they would laugh their ****s off!