1975 Chrysler 75 HP Outboard Quit Running Please Help Don't Know $#!& about boats

awillige4

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So my father in law gave me his 1975 Chrysler Bass Boat with a 1975 75 HP Outboard motor on it last year. Boat had been sitting in his garage since 84. Brought it home cleaned the carbs put new plugs in it. New fuel line and gas tanks. Lower unit grease the whole nine yards. Fired it up in driveway ran great got water running through it. Took it out to the lake fired right up ran like a champ for about 20 mins then died. Started right back up ran great for about 45 mins then died again. Could never get it to fire back up. Got it back to the house everything seems right.... getting fire and fuel but won't start up. Dad thinks it could be the ignition control module????? We checked and bypassed the kill switch but still nothing. Haven't touched it since before winter fixin to start trying back at it. Any Suggestons?????? Service Manual to be downloaded??(free)????
thanks in advance
 

MickLovin

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Re: 1975 Chrysler 75 HP Outboard Quit Running Please Help Don't Know $#!& about boats

Re: 1975 Chrysler 75 HP Outboard Quit Running Please Help Don't Know $#!& about boats

I had 2 of these motors and have a cdi go on me but I could tell as it was only running one 2 cylinders, luckily I had bought a 76 model 75hp and put it on my 80 model it worked fine, your problem though sounds like an intermittent problem, so electrical could be the cuplet.
When you haven't been able to start it, have you checked your spark?
Also I didn't actually have a kill switch on either of my 76 or 80 model 75hp's. Another possbility is the coil breaking down?
Frank Acampora would be able to help you more with this.
 

jerryjerry05

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Re: 1975 Chrysler 75 HP Outboard Quit Running Please Help Don't Know $#!& about boats

Re: 1975 Chrysler 75 HP Outboard Quit Running Please Help Don't Know $#!& about boats

Welcome.
Not Frank but I'll add something.
Do a compression/spark check.
Those ok?
Then check the flywheel key.
The older ones usually didn't have a kill switch?
Check the gas for water?
 

Nordin

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Re: 1975 Chrysler 75 HP Outboard Quit Running Please Help Don't Know $#!& about boats

Re: 1975 Chrysler 75 HP Outboard Quit Running Please Help Don't Know $#!& about boats

Sounds like the flywheelkey is shared.
Set the remotecontrol at neutral and unhook the throttle connector, push the throttle back as far as you can (idle set screw against the block). Pull out all plugs and put a screwdriver in the top hole. Turn flywheel clockwise and stop when the screwdriver starts to move back in to the cyl. This is the TDC and now look at the flywheel. The 0 dgr.mark at flywheel shall point at the 0 mark at the blockpointer or almost .
If it is far away the key is shared.
 

oldboat1

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Re: 1975 Chrysler 75 HP Outboard Quit Running Please Help Don't Know $#!& about boats

Re: 1975 Chrysler 75 HP Outboard Quit Running Please Help Don't Know $#!& about boats

saying you have "fire and fuel" but it still won't start? If you are sure -- at the point you are testing -- you have good spark and that the fuel is fresh (think you said you have new tanks), believe I would check compression. Need a screw-in type tester, and look for even readings between cylinders.
 

jerryjerry05

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Re: 1975 Chrysler 75 HP Outboard Quit Running Please Help Don't Know $#!& about boats

Re: 1975 Chrysler 75 HP Outboard Quit Running Please Help Don't Know $#!& about boats

Fuel and fire??
Still no start?
Flywheel key.
 

oldboat1

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Re: 1975 Chrysler 75 HP Outboard Quit Running Please Help Don't Know $#!& about boats

Re: 1975 Chrysler 75 HP Outboard Quit Running Please Help Don't Know $#!& about boats

hey Jerryjerry -- Can he check for a sheared key by manually rotating flywheel? That is, if completely sheared, the flywheel should probably spin on the shaft with little or no resistance(?) If the key was partially sheared, and the flywheel slipped to another position, the timing would be thrown off I think. Either way, though, still spark? Thanks.
 

Nordin

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Re: 1975 Chrysler 75 HP Outboard Quit Running Please Help Don't Know $#!& about boats

Re: 1975 Chrysler 75 HP Outboard Quit Running Please Help Don't Know $#!& about boats

Oldboat1, the key is for right location of the flywheel to the crankshaft. The taper at the top of the crank is for holding the flywheel in place to the crank. The flywheelnut must be torque to right value, if not........key will share.
If the engine has had a backfire the key can share, BUT the flywheel will still be at the crank by the taper.
If the flywheel just moves a couple of dgr. (5-7 or more) the timing is out. It still will give spark, BUT never start.
 

oldboat1

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Re: 1975 Chrysler 75 HP Outboard Quit Running Please Help Don't Know $#!& about boats

Re: 1975 Chrysler 75 HP Outboard Quit Running Please Help Don't Know $#!& about boats

Thanks, Nordin.
 

MickLovin

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Re: 1975 Chrysler 75 HP Outboard Quit Running Please Help Don't Know $#!& about boats

Re: 1975 Chrysler 75 HP Outboard Quit Running Please Help Don't Know $#!& about boats

Oldboat1, the key is for right location of the flywheel to the crankshaft. The taper at the top of the crank is for holding the flywheel in place to the crank. The flywheelnut must be torque to right value, if not........key will share.
If the engine has had a backfire the key can share, BUT the flywheel will still be at the crank by the taper.
If the flywheel just moves a couple of dgr. (5-7 or more) the timing is out. It still will give spark, BUT never start.
Thanks for that Nordin, I learned something about the flywheel today as well.
 

jerryjerry05

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Re: 1975 Chrysler 75 HP Outboard Quit Running Please Help Don't Know $#!& about boats

Re: 1975 Chrysler 75 HP Outboard Quit Running Please Help Don't Know $#!& about boats

The flywheel nut is tourqed with 95#
It shouldn't spin freely unless the nut's not tight.
 

oldboat1

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Re: 1975 Chrysler 75 HP Outboard Quit Running Please Help Don't Know $#!& about boats

Re: 1975 Chrysler 75 HP Outboard Quit Running Please Help Don't Know $#!& about boats

Problem, though, is that the nut might not be torqued down sufficiently and results in a sheared key -- know from experience, unfortunately, that the flywheel then spins freely. Starter works perfectly, of course, turning just the flywheel -- but that's all that's working. I had a partially sheared key on my old lawnmower last spring, and the mower wouldn't start (kicking back, the whole thing) -- then pulled the flywheel, replaced the key and reset the flywheel, and the mower fired right up on the first pull. (Timing issue because the flywheel had moved, as described above.)

awillinge -- agree that a sheared flywheel key could be the problem. Will change my recommendation to suggest to first check to be sure the flywheel is spinning the engine. If so, do a compression check. If comp check is OK, pull the flywheel to check key and (potentially) reseat flywheel. If still not starting and no apparent cause, think the next step would be recheck the plugs (insure correctly gapped), and then go back into the carb and see what might have been missed. It could still be the CDI unit periodically failing, but thinking AT THE TIME you are getting spark, the engine should start. Trying to come up with the easiest checks to make first.
 

awillige4

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Re: 1975 Chrysler 75 HP Outboard Quit Running Please Help Don't Know $#!& about boats

Re: 1975 Chrysler 75 HP Outboard Quit Running Please Help Don't Know $#!& about boats

Wow awesome to see all the responses and helpful tips. I am planning on getting started next weekend (hopefully) will just get after it and check everything. You can count on me to respond for any fixes as well as ask about any problems I might run into. Again thanks to all who responded.

Happy Boating

Thanks Dusty
 
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