1977 Johnson 70Hp - Dies when placed in gear 70EL77S w/VIDEO

[airbus320]

Greetings,

I recently acquired a new-to-me boat with a 1977 70HP Johnson outboard.

The motor will only start with the warm-up lever at about 50%-75% of its travel (up). Once started it idles, but quickly dies once the warm-up lever is dropped to it's lowest manual position. As you may be aware, the warm-up lever drops to a stop below the lowest manual setting once the motor is shifted into gear. The motor cuts out immediately upon shifting into gear.

I am a licensed aircraft mechanic and have some familiarity with smaller outboard maintenance and repair. However, I have not done any troubleshooting on the issue...yet. The original owner is coming tomorrow to take a look first. He told me that the motor ran great this summer, with no related issues. I also wanted to see if anyone has experienced this issue as well, so I could go to the table with a bit of knowledge.

Hopefully,the attached video will better demonstrate the problem.

Please note:
-The prop spins freely by hand when the control lever is in neutral
-The prop is has resistance in FWD/REV when turned by hand and the flywheel starts to turn. I haven't disconnected the ignition yet, so I didn't move it by hand through a full turn in gear. However, it feels very tight.

Any help or suggestions would be greatly appreciated.

Thank you!

JD

 

[Barnacle_Bill]

Rebuild the carbs then do a link & sync.

 

[flyingscott]

Do a cylinder drop test see if they are all firing also do a compression test.

 

[Michawilden]

I'd also do the drop test. Let the engine run in an low rpm at which it wont die on you. Pull out one plug cap with an insulated pliers. If the rpm drops, Your spark on this plug is good. Do this with the other caps, If you pull one cap and it doesn't have any influence on the rmp, chances are that this cilinder does not contibute.

Maybe you can just solve the problem by increasing your idle rpm screw but if bought the boat and the cables where still in its original place, you should suspect a problem or a lying previous owner. Normally in water, your rpm is even lower so it would certainly die on you when you put it in gear. Can you post a photo of the linkage on the engine with the cold start lever in the lowest position?

I wouldn't worry about your lower unit being faulty, In the video it just looks like the rpm is to low which causes it to die.

 

[airbus320]

Thanks for all the great tips!

I think that a carb rebuild and link & sync is a great suggestion and certainly would take the carbs out of the troubleshooting chain. If a minor adjustment or drop test does not isolate the issue that will be my next and most logical step.

I will post additional pictures as requested sometime today.

Low RPM was my first guess, but not knowing how the engine is supposed to sound or run at idle made this determination difficult. I suspect a dead cylinder with bad plug or wire and will do the drop test to confirm. Nothing has changed in the controls rigging, so I do not put much faith in an idle speed adjustment. My feeling is that it may just mask or further compound the issue.

Any additional suggestions would be appreciated.

Thanks again!

Joe

 

[flyingscott]

Your motor is not running on all three cyl do a drop test or you have an electrical/ compression problem. Your controller works fine the small lever is a warm up lever. When you first start your motor that lever is up set it so it idles about 1500 rpm till it warms up. The cables might be a little tight but worry about that later. A better video would have been the motor running with the hood off. I can hear that you are not running on all cyl.

 

[airbus320]

RE DROP TEST: BTW video is processing in youtube and will be posted shortly...

OK, so this is my first time doing this on a larger engine, but a pretty simple process and VERY TELLING

Disclaimer...PLEASE FORGIVE my impromptu insulated pliers...but they work, until my order from AMAZON arrives

Idled engine with warm up at or above 50% as mentioned in previous replies

Disconnected wire from spark plug wire on LOWER cylinder NO EFFECT!/no RPM drop...put it back on
Disconnected wire from spark plug wire on MIDDLE cylinder NO EFFECT/no RPM drop...put it back on

>>>>>>Disconnected wire from spark plug wire on UPPER cylinder ENGINE DIES!<<<<<

AM I RUNNING ON ONE CYLINDER...OR AM I LOSING MY MIND?!?! :mad-new::mad-new::mad-new::mad-new::mad-new:

 

[airbus320]

RE DROP TEST: BTW video is processing in youtube and will be posted shortly...

 

[1983 ercoa 21']

Do a compression test !

 

[airbus320]

Do a compression test !

Have you viewed my last video? I am only getting spark on two cylinders. Why would I do a compression check (Yet). Shouldn't I figure out my figure out my ignition problem first?

 

[racerone]

Sorry, but a compression test costs no $$$ here.--The next test is to see if you have spark that will jump a gap of 7/16" on all 3 leads.---These are the most important bits of information required by experienced folks to be able to steer you in the right direction.

 

[flyingscott]

You definitely need to do a compression to to determine if the motor is worth fixing if it is good you can go on from there.Then spark test will help you determine if you have any spark. You are running on 1Cyl the top one that's why it died when you pulled the plug wire. The middle one #2 and bottom #3 are doing nothing. If you have spark on 2 cyl and one does nothing compression check.

 

[airbus320]

Thanks for all the suggestions.

Drop test confirmed the problem as coils on the lower two cylinders inoperative, causing all aformentioned symptoms.
Put in new coils and everything works as advertised.

Thanks again for your help!

Joe

 

[airbus320]

I can hear that you are not running on all cyl.

:nod::nod::nod::nod:

 

[1983 ercoa 21']

Have you viewed my last video? I am only getting spark on two cylinders. Why would I do a compression check (Yet). Shouldn't I figure out my figure out my ignition problem first?

Excuse me I didn't watch the video didn't want to burn up data.

 

[David Young]

Yep, your running on one cylinder

 

[Michawilden]

Great to hear that the problem is fixed with new coils. I usually swap the coils arround to see if they work properly. I also clean the coil bases and connections. and I measure the coils resistance. corroded connections can also cause problems. This procedure can potentially safe you money and doesn't cost you a dime. (Or in dutch a stuiver)