Chanpionman, Rudetech1 or Seahorse

[Dub3]

OK I'm still trying to track down the elusive weak- no spark as a possible cause for my poor idle. The latest thing I've done is replaced all the plugs with Champion QL78YC gapped to .030. Started the engine and ran it at idle up to 2000 RPM only.
Cycled the trim full range at idle (per Championman)

Results: 1. Still rough idle under load. 2. trimmed out or level, no load, runs smoother, trimmed all the way in runs rougher and exhaust has noticablely more smoke. Trim out again it smooths out and less exhaust smoke.

Shut engine off and next day pulled the new plugs. Noticed that plugs 1, 5 and 6 were white and little if any moisture. Plugs 2, 3 and 4 were light brown with noticable fuel moisture on them.

Rechecked the spark output and discovered it to be very erractic on all but cyclinder 5. Switched spark plug wires and got some improvement but never a regular 7/16 inch spark. ( not even 1/4 inch spark) tried removing plug wires and testing spark output at the coil. Did not get good results from spark tester, however I did notice that on several coils the spark was jumping to the exhaust manifold!! This leads me to believe my tester is faulty and at least on those cyclinders ( 4 and 6) the output is good.

I have decided to buy new plug wires and see if that helps I also plan to check the recirculating system for problems there. Any other suggestions?

I'm still puzzled at the differance in plug color and suggestions? Would be great if I had a peak reading voltmeter

[ChampioNman]

Are you sure on your cylinder numbers? Port side is 2,4,6 STBD is 1,3,5. Also on top of the block at the power pack on the starbord side there is a black wire with yellow trace that comes up from the shift linkage. Unplug that connector and retest.

[SEAHORSE]

Make sure the motor can turn at least 300 rpm while cranking with the plugs installed while checking 7/16" spark gap.

remove each coil and sand the ground straps and mounting boss to remove any oxidation.

check resistance of each plug wire, there should be none to speak of. The inner spring terminals or wires can get corroded or wallowed out.

Look for any melted plastic under the black coils on the stator under the flywheel. Also inspect each magnet for movement or chips or cracks.


what are compression numbers?

who adjusted the carbs and sync'd the linkages and throttle plates?

how many turns out on each carb adjustment?

what temperature is each cylinderhead after a 5 minute idle in the water, not on a hose?

What is top rpm with a normal load?

when was the motor last decarboned using Evinrude Engine Tuner?

Remove the drain screws from each carb and see if they are a clean shiny brass or have a dark colored deposit on the very ends of the threads.

[Dub3]

Some of the information you requested I have:

compression 95-102 across all cylinders,

spark test was done with all plugs out will have to check RPM.

no noticable resistance in plug wires,

the drain plug in the carbs are clean( looks like they have a coat of pale yellow/gold coating but very clean looking),

don't know who adjusted the carbs last. I was going to try, however the idle mixture screw doesn't have a slotted head. Don't know what it takes to make the adjustment.

Don't know turns out on each carb as I can't tell what type of tool makes the adjustment.

I sync'd the throttle linkage myself and believe it to be correct. All carbs fully closed at idle and the cam follower matches up with the index mark.

Top RPM is 5300 with 62 MPH, 14.5 X 24 Raker and 20 Sprint fish/ ski boat one person full tank of gas.

I decarbonated with Evinrude Tuner last year about 50 hrs. ago and then again with sea foam last week. Hve been running 32 oz Sea Foam in gas past 2 weeks (1/2 tank of gas)

I will check blak coils in stator and clean the ground straps on each coil.

[Dub3]

Championman

Yes I know where you are going with the cylinder numbering (possible kill switch problem) However the only cylinder that has a consistant spark is lower starboard cylinder #6. My manual show that #1 is the highest cylinder with #2, next #3, next and etc. until #6 is the lowest. I will unplug the black wire with yellow trace and re test

[ChampioNman]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by Dub3 &raquo;</td></tr><tr><td class="quote">Championman

Yes I know where you are going with the cylinder numbering (possible kill switch problem) However the only cylinder that has a consistant spark is lower starboard cylinder #6. My manual show that #1 is the highest cylinder with #2, next #3, next and etc. until #6 is the lowest. I will unplug the black wire with yellow trace and re test</td></tr></table>

Not even close, shift interruptor switch on the shift linkage may be sticking. The swicth cuts off 3 cylinders to assist in shifting. If it is sticking it may be knocking out 3 cylinders spark. After market Power packs can vary on which 3 plugs cut out in the firing order. That junk in the bottom of your carb bowls is the beginning of varnish.

[SEAHORSE]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by Dub3 &raquo;</td></tr><tr><td class="quote">Some of the information you requested I have:

compression 95-102 across all cylinders, OK

spark test was done with all plugs out will have to check RPM. test rpm with plugs in

no noticable resistance in plug wires,

the drain plug in the carbs are clean( looks like they have a coat of pale yellow/gold coating but very clean looking), is it a coating that you can scrape off, or normal color of the whole brass screw?

don't know who adjusted the carbs last. I was going to try, however the idle mixture screw doesn't have a slotted head. Don't know what it takes to make the adjustment. 9/64" allen head - use a ball-type


Don't know turns out on each carb as I can't tell what type of tool makes the adjustment. 9/64" allen head - use a ball-type

I sync'd the throttle linkage myself and believe it to be correct. All carbs fully closed at idle and the cam follower matches up with the index mark.

Top RPM is 5300 with 62 MPH, 14.5 X 24 Raker and 20 Sprint fish/ ski boat one person full tank of gas. too low - get about 5500-6000

I decarbonated with Evinrude Tuner last year about 50 hrs. ago and then again with sea foam last week. Hve been running 32 oz Sea Foam in gas past 2 weeks (1/2 tank of gas)

I will check blak coils in stator and clean the ground straps on each coil.</td></tr></table>

[Dub3]

Wow, how- are- can it be elliminated or checked out? I assume that would only be at low speed when you are shifting.

[ChampioNman]

Unplug the connector!!

[THE WITCHDOCTOR]

[rudetech1]

If the spark plugs are discolored from 1 bank to the next, I'd be checkn the stator voltage too. Left bank and compare it to the right bank. Still could be the carb adjustments.