1973 evinrude 115 hp starting problem

[GREE]

Hello, I've posted a starting problem before in the past and I'm still troubleshooting this problem. I changed my battery cable to 2 ga. Copper welding wire, I've had my armature polished new brushes replaced my battery bc it tested bad, and even changed out my starter solinoid. I tested voltage at the starter and starter solinoid today. The battery cable produced 12.7 volts, the yellow wire on top of my starter solinoid produced on avg 9.5 ish, and the wire from the solinoid to the starter produced 10 volts at Max. The yellow wire on the bottom of the solinoid is a ground but it is connected to the nuetral safety switch beside the gear linkage I replaced that wire completely from one side to the other and I'm at a lost not sure if the red and purple wire is giving 12 volts to the key switch and to the yellow wire to give the starter what it needs gonna trouble shoot more tmr but wondering if you all had some ideas. Thank you all for your help.

 

[oldboat1]

Wire voltages aside, did you try to jump start? Regular jumper wired from your truck directly to the starter -- positive to stud on starter, ground to starter bracket. Need to be sure the starter is functioning normally if it gets the voltage (i.e., gear snaps up and engages the flywheel, swiftly cranking the engine).

 

[GREE]

No sir I have not tried that yet I was planning on it tmr. I also see a fuse in the diagrams what size fuse should be on the red and purple wire to the battery for charging?

 

[oldboat1]

20 amp fuse.

 

[GREE]

Thank you. If the starter does as it should bc I had it rebuilt at a starter shop I took it back to them and they said it sounds good with great torque is what they told me. So that's why I'm assuming my starter is good.

 

[oldboat1]

fair assumption. good info. solenoid to starter should be 12V plus when switch activated. Would start by cleaning connections (sandpaper to a bright shine).

 

[Fed]

Put the negative wire of the meter (black) on the starter motor case, put the positive wire of the meter (red) on the starter motor positive terminal, turn the key to start, what Voltage do you read on the meter?

 

[GREE]

Hello again I tried that as you said fed it read 10.1 volts even after I put the negative on the body of the starter. I took out the spark plugs and it was cranking fast. Put a compression tester on it. Going 1-4 it read, 120,90,120,120. I can't think of anything else at all if you all hopefully might think of something thank you all.

 

[interalian]

That 90psi reading is telling. You may wish to remove the bypass cover on that cylinder and inspect the rings. Gasket is cheap.

 

[GREE]

I kinda figured that but was hoping not to hear it lol. Could it be bc of carbon build up?

 

[interalian]

Possibly stuck rings due to carbon. Inspecting them will show it. Could also be a head gasket leak.

Viewed from the rear, cylinder ID:

P---S
2---1
4---3

 

[GREE]

Yup yes sir. Stupid ? Would the rings spin while installed in the motor?

 

[interalian]

There are no stupid questions. Rings are pinned so they don't rotate, otherwise the ring may turn on the piston and a ring end would catch on a port. There's one pin in each piston's ring groove/land, 180 degrees apart. Sometimes the pin can work loose on a motor that's been overheated.

 

[Fed]

So what does the starter motor do or not do when you turn the key to start?

It should work fine at 10 Volts.
Powerhead or gearbox "seizure type" problem would pull the Voltage down below 10 Volts.
Right now I'm suspecting a slipping bendix clutch if you tell me it's not turning the motor over fast enough.

 

[GREE]

Interalian thank you for the info. Fed the starter cog spins around maybe two times half a second later it does the same thing it's hesatant and i don't know if it's due to carbon build up sticking a Piston ring cause I could visually see a bunch of dirty gunk on the Piston head through the spark plug hole. But when all the plugs are out it spins like it should and awesome and keeps 10 volts at the starter even testing from starter body with the negative hooked up to the body.

 

[jbuote]

Pretty new to outboards, but after reading all this, figured I might throw this out there..
​My 71 50hp had issues starting when I first got it. It would do sort of what you described.. Starter would crank slowly, kind of like the battery was no good.
Had the starter looked at, and load tested the battery.. All good.

With plugs out, it'd turn over just fine, but with plugs in, it was very sluggish..
​In my case, I found the flywheel key was sheared. I replaced that, and then it started just fine..

This of course would not address the low compression issue you seem to have on one cylinder....

So, I guess I'm suggesting this as a question to the pro's here..
​Would it be worthwhile at this point to have OP verify flywheel key is good too? :noidea:

Just a thought.. lol

 

[Fed]

Watch the nut above the Bendix, see if it's spinning when the Bendix is stalled.

 

[GREE]

The nut above it does not spin. I asked my dad about the flywheel key and he said usually if you have backfires and I've had a couple I know at least one decent one and a couple small ones

 

[jbuote]

Yup... Had that too on mine...
​Again, NOT a pro here.. Still new, but you're describing almost to a "T" what happened to me..

​Can't say for certain, but sounds like it might be worth taking the flywheel off and checking the key..
​Use proper puller, strap wrench etc.. and make SURE to check tapers on crankshaft and in flywheel while off, and then torque properly when putting flywheel back on.., VERY important to properly torque..

​That's all I had to offer, and may not be your issue, but thought it might be worth checking, if nothing else, to eliminate the possibility...
Still doesn't address the low compression which should be looked at, but...

​Back to the shadows with me... LOL
​Hope it made sense and helps somewhat..

 

[GREE]

Yes sir it does probably the back fire made it go out of sync causing carbon build up plus whoever done the carbs on my boat was way wrong so the motor was getting way too much for cause there was no idle screws in there for the .003 hole in the middle so yeah probably carbon bet and they key and the backfire makes sense to me lol