1978 70 HP Johnson, Wont Start, Need help

[fsutim]

One week ago I purchased a boat with a 1978 70HP Johnson. The man said it has been sitting for about 2 years and he rebuilt the engine aproximately 3 years ago. When I purchased it from the guy it fired right up with a charger on the battery and the guy informed me that I would need to purchase a new battery. I Did. Every time I try and start it even after the new battery is in it turns really slow with a pause inbetween each crank, after trying it a few more times or coming back to it a few minutes later it seems to do the same thing and then out of no where it will turn real fast and the engine would start. Today I took it out and it started up like it normally does slowly, but once I got to my first fishing spot it left me stranded, it did the same thing, a bunch of slow cranks and no start. I checked the carb and it was getting fuel. Any sugestions would be Great. Thanks, Tim

 

[Hooty]

Re: 1978 70 HP Johnson, Wont Start, Need help

I'd start by cleaning all the large cable connectors. Start at the battery, remove the cable from the battery post, clean the cable and post and work out from there. <br /><br />c/6<br />Hooty

 

[rickdb1boat]

Re: 1978 70 HP Johnson, Wont Start, Need help

Check and clean all the battery connections from the battery to the starter selonoid and then from the selonoid to the starter. This includes the negative terminals. You are mixing a 50:1 oil/fuel ratio, correct? Had to ask.

 

[fsutim]

Re: 1978 70 HP Johnson, Wont Start, Need help

I have been using a 50:1 ratio. I will try the cleaning method tommorow and post the results, thanks for the ideas, Tim.

 

[fsutim]

Re: 1978 70 HP Johnson, Wont Start, Need help

I cleaned the battery and terminals and went to the solenoid and starter including the ground wires. I went to try and turn it over and it is still doing the same thing. It is only turning about 1 rotation every second, with a short pause after each rotation.

 

[K Hultgre]

Re: 1978 70 HP Johnson, Wont Start, Need help

Sounds to me like the brushes inside the starter are not making contact, they could have rust inside their holder preventing the spring from pushing them against the armature. Also is the pause after a complete 360 deg rotation of the flywheel or the starter bendix (gear)?

 

[fsutim]

Re: 1978 70 HP Johnson, Wont Start, Need help

The bendix turns about 1 rotation and the fly-wheel turns 1/3 of the way.

 

[rickdb1boat]

Re: 1978 70 HP Johnson, Wont Start, Need help

Have you tried jumping straight to the starter with jumper cables and bypassing the selonoid? That would be your last shot before rebuilding or buying a new starter. I also am betting the brushes and innerds are rusting and sticking, including the brushes in the holders. You have the option to dismantle it at this point with nothing really to lose. Might be able to clean it up and install new brushes and viola, off you go. Many automobile starter rebuiders will rebuild a outboard starter for $40.00 or so if you have one near you. You can get a used one from the link below for about $100.00 if nessesary.<br /><br /> web page<br /><br />Might try here also:<br />$85.00 and 90 day warranty<br /> web page

 

[fsutim]

Re: 1978 70 HP Johnson, Wont Start, Need help

could you please tell me how I would jump to my starter? Do I jump right off my car battery?

 

[K Hultgre]

Re: 1978 70 HP Johnson, Wont Start, Need help

First, do this in a open area. Make sure you do not have gas vapors or liquid gas laying around inside the engine area.<br />Hook one end of the negative jumper cable to the starting battery then find a sutiable ground on the engine block to hook the other end.<br />Protect the positive cable end that will be touching starter from shorting against anything.<br />Hook other end of the positive lead to the Battery (not in enclosed area).<br /><br /> Do not hook positive end to starter. Sparking at the battery is not a good idea, I have had one (battery) explode, not a pretty site.<br /><br /> Now with negative hooked up and one end of positive on the battery. Touch the free positive end of jumper cable to starter Brass nut (should have red battery cable attached to it). <br /> <br /> It will scare you at first. Dont do this too many times because it will leave slag on the threads or burn them off completely and make disassembly difficult.<br /> If the starter spins as you described earlier then you have starter problems. If the starter spins full speed with out hesitation you most likely have solenoid problems.<br /><br />After you pull apart the starter check brushes and holders as posted earlier and the armature (part the brushes ride on) for one of the pads to be corroded or lower than the others. If it is not too bad you might be able to use a file and clean it up. If you know how to use a Ohm meter, ohm each leg of the armature and make sure they are about the same, I will guess nothing more than 10 ohms each. If you get 0.00 ohms you are either touching the wrong spot or you have a "dead" starter and time for a rebuild Sometimes bringing your starter to a rebuild shop is more time consuming but costs the same as buying used and you get a better warranty.<br /><br />Good luck.

 

[ledgefinder]

Re: 1978 70 HP Johnson, Wont Start, Need help

Ditto on jumping the solenoid, I've definitely had a couple OMC solenoids go bad & behave exactly as you're describing.<br /><br />Couple notes. One, I have to get REAL good connections before the starter will work well; bolt three of them, then put the fourth on solidly. That's on the V4s, the 3 cylinders may be easier on their starters. Two, if you replace the solenoid, don't use a generic automotive solenoid as they are wired differently.

 

[fsutim]

Re: 1978 70 HP Johnson, Wont Start, Need help

I used jumper cables and jumped the starter to see if it would turn differently. It did the same thing. So I took apart the starter and cleaned inside real good. I didnt replace the brushes but cleaned them and noticed one of them was pretty wore down. Some where in this process I managed to lose a spring that props up the brush, so I used a spring out of a mechanical pencil, It is a little shorter and not as heavy duty but it still seems to hold it up, I'm not sure if this made any difference.I then hooked it back up to the engine and tried to start it, this time it spun probably twice as fast as it has been, but it still isn't close to normal speed. Should I try a brush kit, or is it probably dead? Or any other suggestions before I have to replace the thing. Thanks, Tim

 

[Chinewalker]

Re: 1978 70 HP Johnson, Wont Start, Need help

Definitely rebuild the starter with new brushes. Also, make sure the armature where the brushes ride is clean. Compressed air helps get the metal dust out of it.<br /><br />The only other thing I can think of would be a complete change of direction. Are you seeing any excess fuel on the water? Had a motor once do what you were describing and it turned out the carbs were flooding out the motor enough that I was trying to compress liquid gasoline in the cylinder chambers - liquids don't compress very well at all! The tank had been sitting in the sun and the gas expanded, forcing it's way through the fuel system. The motor was dumping puddles of fuel on the water. Once I got the carbs rebuilt it was fine...<br /><br />- Scott<br /><br />- Scott

 

[fsutim]

Re: 1978 70 HP Johnson, Wont Start, Need help

Thanks for the help everyone, I'll try and find a brush kit around town today.