76 Johnson 85 hp V4 runs on 3 cylinders

[hyflyer]

Engine starts and runs on 3 cylinders, 4th one kicks in now and then with lots of power for few seconds and drops back to 3 cyls. Carbs have been cleaned and rebuilt, new fuel in tank, new power pack, find oil on top two sparks plugs, gasie smell when running,fuel pump ok. black carbon on outside of #1spark plug just at end of plug wire cover. Shop put in wrong rectifier, burned wire and tack quit, replacement tack does not work, Won't come up to speed.

 

[Bosunsmate]

check spark jumps 7/16 gap

 

[jimmbo]

An Engine with a dead cylinder isn't going to rev up well, except when running on a Hose

When you say "oil on top two spark plugs"... Oil on electrodes and insulator, or on the outside of the plug?

Cylinders 1 and 2 are fed from one 2 bbl carb, that shares a Float and Fuel bowl, if one cylinder is rich at speeds above idle, the other should also be as well, unless there is an air leak in the induction system on the other one.
Plug #1 might have a cracked Insulator.

 

[Bosunsmate]

run at night, check no shorting on that carbon tracing

 

[racerone]

Run with a timing light on # 1 to confirm it is the issue cylinder.----Then swap # 1 and 2 coils to see if issue follows that coil.-----Some simple trouble shooting will solve this.

 

[hyflyer]

I ran cyls 1 and 3 on spark tester, did ok, turned on light in tester. Cyls 2 and 4 would not turn on light in tester. ignition coils ohm test ok. Is this a stator problem.
Thanks,

 

[hyflyer]

An Engine with a dead cylinder isn't going to rev up well, except when running on a Hose

When you say "oil on top two spark plugs"... Oil on electrodes and insulator, or on the outside of the plug?

Cylinders 1 and 2 are fed from one 2 bbl carb, that shares a Float and Fuel bowl, if one cylinder is rich at speeds above idle, the other should also be as well, unless there is an air leak in the induction system on the other one.
Plug #1 might have a cracked Insulator.

Yes it has cracked insulator on #1. Oil is on threads and around the spark plug seal. It is worse on two top cylinders. Oil and exhaust gunk drains out around prop when sitting after running.
Thanks

 

[racerone]

Does spark jump a gap of 7/16" on all leads, yes or no.----Post the compression numbers on this 40 year old motor.

 

[jimmbo]

Try a new plug on #1

 

[hyflyer]

Does spark jump a gap of 7/16" on all leads, yes or no.----Post the compression numbers on this 40 year old motor.

Spark jumps gap on 1 and 3, won't jump gap on 2 and 4. Three cylinders had compression of 125 and the other one was 120. Coils on cylinders 1 and 4 do not pass ohm test even though cylinder 1 was ok on spark jump test. Will replace spark plug on cyl one. Am confused about cyl one. I have new coils ordered.

 

[hyflyer]

Replaced coil on cyl #4 with NOS OEM coil. It passes ohm test but won't pass spark tester test. It does fire the spark plug. Cyl #2 does the same thing. Put in new spark plugs, no changes.
Does this lead to the stator being the problem for cels. #2 and #4

 

[jimmbo]

What condition is the Wiring in prior to the Coils? You might have a bad CD unit

Maybe you have already seen this, but here a wiring diagram for your engine



On a side note. There is a flaw in the diagram as I think there should be a jumper between #6 and #7 on the Terminal Block, otherwise the charging system won't work

 

[racerone]

Test sensor coils.

 

[racerone]

Test sensor coils.---Test charge coils.

 

[hyflyer]

I have tested both the sensor and charge coils with the dvom, according to service manual. Test ok. Replaced ignition coil on cyl #4 which tested bad. New coil tests 1264 secondary high ohm setting and .2 ohm primary low ohm setting. The book calls for 1300 +- 200 so that seems ok. Book calls for .1 +- .05 on primary. Is reading of .2 ohm excessive. Switched ignition coil from #1 which tests ok to #4, Cyl #4 still will not fire spark tester using the good coil off of #1. Cyls 2 and 4 still will not pass spark test with spark tester, even though ignition coils 2 and 4 both test ok. Cyls 1 and 3 pass spark test. Tested rectifier, tests ok. Power Pack replaced 2 years ago and has maybe 3 hours running time on it. Now I am baffled.
Thanks for your input






3

 

[Bosunsmate]

Hows the stator testing out?

 

[hyflyer]

The stator tested ok with the ohms readings but is still on the engine. Should I take off the flywheel and bench test it.

 

[Bosunsmate]

The stator tested ok with the ohms readings but is still on the engine. Should I take off the flywheel and bench test it.

Id test it on the engine, see what Volts you are getting

 

[faulk9]

power pack is bad on that side switch them and see if the problem doesnt switch to the other side

 

[racerone]

faulk9----Why did you post that ??---I believe that motor only has 1 powerpack !