power loss on '78 85hp crossflow

[Thumpbass]

I have a '78 85hp johnson V4...I took it out yesterday and experienced the following problem. Started relatively fine...out of gear in the start position it would reach 3500-4000 rpms and idled fine in the warm up section 1000 or so rpms. When I put it in gear it would idle fine in the 600-ish rpm range but as i increased throttle (in gear) it would only get up to 2500 rpms (not even plane out). Initially it would have very short sudden bursts of power but only for a split second. After putting it back on the trailer I pulled the plugs and the starboard plugs were clean and slightly wet but the portside plugs were black and sludgey looking. Also the last few times I have taken the boat out it has flodded really easily (appearently)...if I ran a bit then tuned off and fished a long bank (long enough for the engine to cool off) it would be extremely hard to crank..would have to run the starter hard to eventually get the engine to fire then it would be fine. I noticed this yesterday as well but it was much worse. My guess is that I'm not getting spark on the port side (or have gradualy been losing it) and it's causing the motor to flood and the plugs to foul. Does this sound right or does anyone have any other insight or suggestions? ...plugs, coils, powerpack may be? any thoughts?...I havent checked compression but at the beginning of last season it was over 100psi and equal in each cylinder but i guess it wouldnt hurt to re-check it. thanks

 

[iwombat]

Re: power loss on '78 85hp crossflow

Your hunch about not having spark is probably correct. Compression check and a spark test are in order.

 

[flabum]

Re: power loss on '78 85hp crossflow

check all the ground connections. I had a brand new powerpack break a gound wire last week killing one side...acted just like yours. it could also be a bad pack or stator.

 

[Thumpbass]

Re: power loss on '78 85hp crossflow

so it seems like i have read where you have to re-adjust the max spark advance or timing when you replace a power pack...is this always the case or is it more along the lines of "you might have to re-adjust the timing"...how do you know if the timing needs to be re-adjusted? I haven't done any trouble shooting yet so i don't even know if it's the power pack, just curious.

 

[wavrider]

Re: power loss on '78 85hp crossflow

If you need to set the timing go to faq section and read Joe Reeves timing procedure, simple and straight forward, good advice.

I use a timing light and check the spark on all spark plug wires while the engine is running.
Found and intermittent coil on my 85hp rude using that method.

 

[ezeke]

Re: power loss on '78 85hp crossflow

The best thing you can do for your particular motor is to leave the timing alone unless someone has done something to change it.

Whenever you have a failure to respond properly for no apparent reason, do a compression check and spark test - all plugs out and do it by the book.

If someone has had your flywheel off, you might want to check to be sure that the key is in place and that it is torqued to 105 ft. lbs.

If you want to read a thread that will perhaps help you to understand the significance of the testing, and also emphasizes why an annual de-carbon is so important, read through this: http://forums.iboats.com/showthread.php?t=200395

 

[Thumpbass]

Re: power loss on '78 85hp crossflow

OK compression test was good and I am getting 7/16 spark on my port side but my starboard side is not getting any spark period. I replaced the power pack (with a new one) and still no spark. I have a 79 100hp with a blown cylinder that I use for a parts motor so I pretty much can pull any ignition part from it that I need. I guess I'll replace the coils on the starboard side since I have a spare set of good ones but I'm guessing that my problem lies before the powerpack...could the timer base or rectifier being bad cause a no spark issue in only one side? THANKS!

 

[wavrider]

Re: power loss on '78 85hp crossflow

you have a type II CD ignition.
could be a charge coil, a sensor or even a powerpack not switching.

Hopefully it is just corroded connections and maybe faulty wiring.

Do a resistance check on the charge coil should be around 560 ohms + or - 75ohms

 

[ezeke]

Re: power loss on '78 85hp crossflow

Could also be a bad ground. Be sure to remove and check the ignition coils for good contact because without it you can damage a powerpack.

Also, Be sure to test the rectifier. "http://outboardparts.com/omc/troubleshooting/printguide.htm"

 

[Thumpbass]

Re: power loss on '78 85hp crossflow

wavrider, when you say a powerpack not switching, are you saying that it's possible that the pack on the port side (that has spark) could be causing or contributing to no spark on the starboard side...just wondering because I replaced the starboard pack with a new one with no change. Thanks for all the info guys!

 

[Thumpbass]

Re: power loss on '78 85hp crossflow

well found the culprit...bad rectifier. just did the ohm test per the manual and it was definitely bad. went and pulled the rectifier of my old 79 100hp with a blown power head and zap...we have spark on the starboard side. started up fast and roared in the driveway...I'll be giddy when I'm doin 40 down the river but for now I think I'm in pretty good shape...thanks again for all the info.

 

[wavrider]

Re: power loss on '78 85hp crossflow

Glad you got it going. Thanks for the follow up.