1978 Johnson 70hp seahorse help needed

[jwracca]

Hi all, and thanks in advance for your help..

Motor sat for 1yr so i put it in the shop for a carburetor job, and the motor would die out when i put it in the water and gave it gas. The mechanic told me the carb job would fix this issue. Well i picked it up and went to the water, just backed it up in water to test it out.. Starts up perfect, put it in gear and bogs down and dies. Ok so the carb kits didnt help this problem.. So i took it home and after some investigation, i found the sensor was not moving with the spring.. Cleaned it all up and now she ran like a top.. next day i go lauch the boat, and the starter sounded like the battery was dead.. Which i just bought a new marine battery, i was puzzeled. But it started and i ran around for about 30-45 mins. Next day i launch and the starter was barely turning the flywheel. so i pulled the plugs and gas sprayed out of the 3rd constant where as 1st and 2nd did not. The starter gets really hot. I have replaced the battery cables to motor, installed new connectors on each end. If i try and pull start the motor it jerks my arm back really hard, until i blow out the gas from plugs. My question is, why is gas steady coming out of spark plug 3 chamber? and Does this sound like a starter issue?


Thank You

 

[Joe Reeves]

Re: 1978 Johnson 70hp seahorse help needed

STARTER: With good jumper cables and a known good battery, run the cables directly to the starter. If no improvement, the starter needs work. If however the starter operates fine with the jumpers, then you have either a loose connection somewhere or a tight but dirty cable connection somewhere.

FUEL: Remove carburetor face plate. pump the fuel primer bulb up hard. If fuel flows from any carburetor, take the engine back to the mechanic for a free redo. If fuel does not flow from any carburetor, I'd suspect (possibly) that the fuel pump diaphragm is cracked, allowing fuel to flow thru it. Not sure if cylinder 3 is the one that operates the fuel pump though, just don't remember.

Are you sure that cylinder number three is firing along with the other cylinders?

 

[jwracca]

Re: 1978 Johnson 70hp seahorse help needed

Thanks for the awsome response.

Ran jumper straight to starter and performed the same. I have another.

I will check the fuel in a min and update.

Thanks again

 

[jwracca]

Re: 1978 Johnson 70hp seahorse help needed

You hit the nail on the head sir. Took breather cover off, dried all three carbs off. Pumped bulb and a steady stream of gas leakes into carb chamber. And thats a 450$ job i paid for.

 

[Joe Reeves]

Re: 1978 Johnson 70hp seahorse help needed

That job isn't that complicated and that shows the guy didn't double check his work. A service manual, advice from this site, carburetor kits, would have you doing just as good (probably better) and close to $300 cheaper!

Going to take it back and have him do it over?

 

[jwracca]

Re: 1978 Johnson 70hp seahorse help needed

No, i don't belive i am bringing it back. I had originally done the kit myself, but i thought i had not done a good enough job myself due to the motor bogging down after i worked the carbs. After bringing it to the mechanic, the motor did the same. Problem wasn't even the carbs. I think he created the problem.

So, i already took the carbs off and put spare kits i had. And the leaks stopped.

But the starter just barely turns the flywheel with a new battery and new cables. So i am thinking the starter is out. Yes, i bypassed cylinoid and starter has same issue.

Thanks Mr Reeves

 

[fireman57]

Re: 1978 Johnson 70hp seahorse help needed

Spray a light coating of WD40 on the starter shaft. If it spins freely after that then you just need a light coating of light grade oil on it like sewing machine oil. If that doesn't work then try it with the spark plugs out. If it doesn't turn easily then you might have overheated the engine. Probably not but could have.

 

[Joe Reeves]

Re: 1978 Johnson 70hp seahorse help needed

But the starter just barely turns the flywheel with a new battery and new cables. So i am thinking the starter is out. Yes, i bypassed cylinoid and starter has same issue.

Yes, a good fully charged battery, and known good jumper cables run directly to the starter should have really whirled that engine over. The fact that the starter still turned slow and got very hot sort of tells the tale (bad starter).

However, as Fireman57 suggests, remove the spark plugs for a double check.... even a failing starter should crank the engine over a little faster. You can tell if the engine is binding by having the s/plugs removed and turning the flywheel by hand also.

 

[jwracca]

Re: 1978 Johnson 70hp seahorse help needed

I should have been more specific, sorry i am not good at explaining things. A few unanswered questions

1. spark plugs out (3) the flywheel spins fast, which is how i noticed fuel was spraying out of carb 3
2. yes, spark plug 3 is firing fine. Tested with spark plug tester.
3. "Not sure if cylinder 3 is the one that operates the fuel pump though, just don't remember." The fuel pump is on cylinder 2.

Thanks for the response fireman, Mr. Reeves

 

[jwracca]

Re: 1978 Johnson 70hp seahorse help needed

Well, i thought i had a spare starter. But i couldn't locate it, so a new starter will be here tomorrow.

I took the starter apart and the brushes and center shaft all looks good. But one of the magnets was broken inside. I pulled out the broken magnet and the flywheel will spin until i choke it, then it just has not enough power to spin it any further.

PS: i can pull start this motor fairly easy.

 

[jwracca]

Re: 1978 Johnson 70hp seahorse help needed

Looks like i will need more of your expertise please. My new starter came in today, so excited i ran out and mounted that puppy on. I couldn't wait to hit that key.. and and rrrrrurrrur urrururrrrr the same thing. flywheel barely turns and starter gets hot.

hmmm

pulled all 3 plugs out and man that flywheel spins like a top...

Compression check was 1. 124 2. 128 3. 130

with one plug it will spin decent, with 2 plugs it just sounds like a dead battery where the flywheel is just barely turning.

I am at a loss here.. i ran jumper cables from my battery in my truck, with the truck running and grounded to the engine and hit starter. still performs the same.

 

[nwcove]

Re: 1978 Johnson 70hp seahorse help needed

is the new starter also connected to boat wiring when you boost it? if so, try unplugging/disconnecting all wiring, then try booster cables.

 

[Joe Reeves]

Re: 1978 Johnson 70hp seahorse help needed

STARTER: With good jumper cables and a known good battery, run the cables directly to the starter. If no improvement, the starter needs work. If however the starter operates fine with the jumpers, then you have either a loose connection somewhere or a tight but dirty cable connection somewhere.

The above is a copy/paste clip from my previous post above. If that new starter is good, and you're running known good cables directly from a good 12 volt battery to the starter... you're overlooking something. Possibly the jumper cables are damaged, corroded somewhat internally? If so, some portion of the cable will get extremely hot.

And a bad cable will result in a voltage drop which will also make the starter get hot.

It's always possible to get a faulty new starter also... happened to me a couple times. Obviously your original starter is bad so there's no loss or wasted effort there.

You say that you bought a new marine battery..... was it... is it fully charged?

 

[jwracca]

Re: 1978 Johnson 70hp seahorse help needed

I will go double check everything.

Yes, new marine battery fully charged.

Also disconnected and used jumper cables straight to starter. Starter works fine as long as the plugs are out.

i will try a new pair of jumper cables, and update.

Thanks Mr. Reeves

Update: Put new jumper cables on my running truck battery, and ran to starter and grounded on motor. Same problem. So i put a rope on the flywheel to see just how hard it was to spin. Cranked on 3rd easy pull.

Both starters i have act like there trying to turn a 1000lbs. When i can spin the flywheel with ease.

I have a repair manual, i will start reading to see if i can come up with something. I sure hope i didnt get a bad starter in the mail..

 

[Joe Reeves]

Re: 1978 Johnson 70hp seahorse help needed

If that starter is a brand new, never before used starter directly from a dealer or distributorship, whoever... that's a starter that you shouldn't have a problem with..... BUT if it's a rebuilt starter, having one act like that is a common problem. Best to avoid the rebuilt ones.

Running the cables directly to the starter..... just to be sure we're on the same page here..... you are running the positive cable directly to the electric starter threaded terminal and the negative cable directly to the powerhead somewhere to ground it aren't you?

Where are you located (roughly)?

 

[jwracca]

Re: 1978 Johnson 70hp seahorse help needed

It looks to be a new starter. But the welds that hold the flat metal brackets are welded horrible.. I think my 3 yr old could weld better than that.

And yes, i am running a positive cable directly to the electric starter threaded terminal and the negative cable directly to the powerhead.

I am in Lake Charles, Louisiana

I took the new and old starter to Advanced Auto to test them, and they said the model number of the starter is not in thier system and they can not perform a true test on them.

So i get back home, and put the OLD starter back on and just tried it.. And it spun it nice and fast and started up.

I am gonna bring it out to the water tomorrow, less than a mile from my house lol... and try it out.. I am really puzzled why the old nor the new starter would not spin that flywheel.. and now all of a sudden it spins..

I scrapped every connecter, tightened every screw, bolt and everything else. But i am afraid i am gonna be out fishing, try and start it and it will do the same thing. i do keep a pull rope with me in case.. and usually i can just pull start it if needed..

Thanks,
Joey

 

[Daviet]

Re: 1978 Johnson 70hp seahorse help needed

Maybe you had a poor ground between the starter and the engine block. When you removed it a couple of times you got a better ground.

 

[jwracca]

Re: 1978 Johnson 70hp seahorse help needed

Maybe so Daviet, but i went outside around 9am. this morning and hit the key to see what it would do.. and its acting the same way.. So i am gonna take the starter off, and all connections and have some 1 on 1 time with some sandpaper and a wire brush. O how i love hunting for problems that wont present themselves. lol

 

[Joe Reeves]

Re: 1978 Johnson 70hp seahorse help needed

I am in Lake Charles, Louisiana. So i get back home, and put the OLD starter back on and just tried it.. And it spun it nice and fast and started up.

That really sounds like the starter was not grounded properly to the powerhead..... too much paint on the powerhead or grounding surfaces of the starter (it happens).

 

[jwracca]

Re: 1978 Johnson 70hp seahorse help needed

Hope you dont mind all the updates, just trying my best.

I took the starter off, softly grinded the flat mount plate around bolt holes to bare metal. Mounted it up and acted the same.

So, i took the starter off and opened it up. First thing i noticed was that the brushes are bottomed out stuck. In other words the springs are not pushing the brushes up.

Second thing i noticed is 3 of the 4 magnets came out with the middle copper section.

I am in the process of making a solid starter out of both.

You know i will update you soon

Thanks for your expertise...