Problems with my 1978 Johnson 70HP outboard! Please help...

[Flyinjrc74]

I am new as of tonight and have some questions...

My real name is Jason Nicodemus from Niles, MI and I am new to boat ownership. I am very mechanically inclined but now I am really baffled!

I bought a 1978 Ebko tri-hull runabout with this 1978 70HP Johnson bolted to the back of it. The boat has sat a couple years and the genious that owned it prior had tried starting it with a screwdriver/shorted out the switch/messed up linkages and the control box would not shift into reverse.

I messed with it for a bit and could not figure the control box out, I put in a new switch but could not get power to engine!

I took the whole shi-bang to a marina in S.B. IN They were able to troubleshoot the problem to one of the cables and the adjustment was off. They got it to the point that it would turn over with the new key switch and cable but the CD3 Coil pack was bad. I found the same year engine in Saginaw,MI and drove up this weekend and bought the whole thing just for parts! I robbed the ignition off of it and installed it on the motor on my boat and within seconds it fired up but the idle was high so I immediately shut it down. I tried again and again without it in water or with muffs on it. Same thing, started and ran fast(It sounded very mean and in time)! I shut it down and used a saws-all to cut my trash container and filled it with water submerging it like it were in the lake!

I again tried to start it again and it would not start up and is now backfiring and smoking alot??? I tried several times to get it to run using the choke and trying to open and close the butterflies for the actual throttle. All we could get was backfiring and smoke!

We have checked the spark(all plugs are sparking brite white), tried starting with fuel line attached and also unplugged? It is getting fuel/it is getting good spark so I am puzzled why it is now not firing in the water.

Then- I moved the throttle forward and back to reverse and now I am back to square one as the throttle control is going back to center and will not go back far enough to go into reverse or center to allow the key to start the engine???

One more thing! The impeller seems to be not operating? When I was turning it over and also when it started there was no water coming out of the exit just below the engine cover on the right side? I will check tomorrow to see if mud daubers may have nested there or possibly a large brown recluse is inside(hopefully not the recluse)?

I appreciate any experience or answers in solving my problems with this engine. I have a whole engine at my disposal to rob parts from if necessary! The only thing wrong with the parts motor is no compression in the center cylinder!

Thank you very much!

 

[jonesg]

Re: Problems with my 1978 Johnson 70HP outboard! Please help...

oi vey, maybe you toasted the pump impellor running it without water.
Depends how long/fast it ran, they can tolerate a few seconds at idle.
You might also not be in the water deep enough to pump.

If it runs on the hose but will not run in the water , thats probably due to backpressure. Weak spark is what I'd look for.

Go to the auto store and get a $12 adjustable spark tester, set it to 3/8th inch gap and see what kind of spark you get.

If the spark is bright blue the carbs probably need rebuilding.
iBoats should have the carb kits.

Did you check the gear oil for water yet?
remove prop and check for monofilament (cuts the prop seal if left)?

I would go through the motor from top to bottom, read the FAQ files link is below in my signature and consider buying the shop manual, not seloc, link is also below for service manual.
Use new seals on drain screws (iBoats sells them).
Change the oil.
Re-lube prop shaft, replace prop.

 

[Flyinjrc74]

Re: Problems with my 1978 Johnson 70HP outboard! Please help...

Thank you for the info. I tested it in water with my modified garbage can on wheels, I am now getting water through the drain hole and I only ran it for about three seconds dry prior to submerging the lower end for further troubleshooting and here is what I come up with...


I don't want to get too big-headed but yesterday I decided to ACT like I was a Johnson certified tech. I started in the morning and by noon had the whole throttle command center figured out and working correctly again!

Now to the engine!!! I figured out it was out of time because I was getting spark/fuel/air and it would not even hick-up with a quick shot of starting fluid! Lots of smoke but no fire. I decided to reverse the #2 and #3 spark plug and it fired up but was still out of time but surprisingly it was very close.

After running to Advance Auto a couple of times to get the correct socket to remove the flywheel I had to make yet another trip to a friends shop to borrow his steering wheel puller to remove the flywheel. I removed the flywheel to confirm my suspicion that the woodruff key was sheared and bingo! Problem solved...

I removed the flywheel from the spare engine and robbed the key from it. After re-assembly it fired right up but still the idle was high and would not trim to low-idle. I had to manually pull the lever inside engine area back to achieve low throttle. It would hold there until I moved the trim on the throttle box up again but would not go to low idle using the trim lever. The screwed the plastic trim adjustment all the way in (towards the rear of the boat) and the problem still remained.

I once again opened up the throttle box. Due to the cable being newly installed and the marina not being able to run it before giving it back because of the bad CD3 pack, I was able to determine that there was an adjustment at that end too. I loosened the set screws (top and bottom) and pushed it through the guide hole another 3/4" and re-tightened the set screws.

Now back to the engine. Within just a few minutes of retracing my steps and some fine tuning I double checked linkages/throttles and all looked good. I fired it up and it was spot on and running excellent!

I need to invest in a Johnson manual for future issues but for now it is time to finish interior upgrades and with a little more luck on my side I will be in the lake this weekend!

I am tickled pink that I was able to figure this engine & controls out and probably just saved myself about $500 or better in marina technician labor and parts!

 

[jtexas]

Re: Problems with my 1978 Johnson 70HP outboard! Please help...

That's no easy puzzle, the control box, good job.

Still a couple things needed before you get it out on the lake. To get you going until your manual arrives, refer to the picture below (it's a later model but the parts are all the same):
Set the idle speed at 1100-1200 on the muffs, make it around 1000 in the barrel, then fine tune it after you get the boat in the water. should be 900-950 in gear, pushing the boat.

The idle set screw should be neither all in or all out, but it does need to be butted up against that throttle lever. If needed, adjust cable length using the black thumbwheel where the cable enters the cowl. The mark on the cam needs to hit the roller dead center (adjust the roller), else she'll fall flat on her face when you try to accelerate. Then make sure the throttle valves are all perfectly horizontal and not beyond at WOT.

Finally, set the WOT timing (this needs to be done any time the flywheel is removed).
First set the TDC pointer:
[note: Rotating the flywheel CCW turns the water pump impeller vanes backwards, so do it as directed for this procedure only, and as little as possible.]

1. rotate the flywheel (clockwise only) until the TDC mark is a few inches from the TDC pointer. Insert a piston stop tool into the #1 hole and rotate the flywheel (CW) until it contacts the stop. With a pencil, mark the edge of the flywheel at the TDC pointer.
2. rotate the flywheel (CW) a few inches past TDC, insert the piston stop tool, and rotate the flywheel back (CCW) until it contacts the stop. Mark the edge of the flywheel again, at the TDC pointer.
3. draw a straight line between your two marks.
4. draw a straight line from the center of, and perpendicular to, the first line to the edge of the flywheel.
5. if your 2nd line hits the 0? TDC mark embossed on the flywheel, you're done.
..........otherwise,
6. rotate the flywheel (clockwise) until the 0? TDC mark aligns with the TDC pointer.
7. loosen the TDC pointer and slide it over to align with your 2nd line.
8. repeat from step 1, until you hit TDC in step 5.

Then follow this procedure very carefully:
http://forums.iboats.com/showthread.php?t=228183
You won't find this in any manual...the manual will tell you it has to be done with motor running full throttle in a tank with a test wheel. Your WOT timing is 19? BTDC.


Note that that running it in a barrel is no indication of how it'll perform under load.

After sitting around unused for a couple years, your high speed jets will be fouled with varnish left behind by evaporating gasoline. Were it mine, I'd rebuild the carbs now. Or if you can't wait for the kits to arrive, at least give 'em a good soak then install the kits next week. Follow the "carb cleaning and rebuilding" thread from the "top secret file" at the top of this forum.