'75 Chrysler Force 75 bad CDI?

[rayeckel]

My '75 Chrysler 75 outboard starts fine when cold, runs great for about 15-20 mins then dies like the key was turned off. Let it sit for about 2 minutes, and it will start right up and run for 8-10 minutes then shut off again, wait a little longer, and it'll run for a shorter period, and so on.

The boat sat for three years until I bought it last February, and since I have had it, this is what I have done:

New battery. New gas tank, fuel lines, primer bulb, and fuel pump diaphram. I removed, dissasembled, and cleaned all three carbs and re-tuned them after putting them back on. New head gasket. New plugs. Removed thermostat, new water pump impeller.

I have had 2 stroke motorcycles do this to me in the past and it was always a bad coil, so I replaced the coil last week. No help.

Could it be the CDI unit going out? Don't those things completely die when they go, or can they become intermittent? It's a pricey part (and it comes with the coil, doh!). Is there something worth pulling the flywheel off to check? (stator, condenser, etc.) The CD box on it now is a CDI 115-3301, and the sticker on it reports a manufacture date of Oct. 2003.

Thanks in advance!

EDIT:

Also, I have bypassed the quick-connect on the gas tank and lightly squeezed the primer bulb while it was running and it still shut off. So I'm confident it's not a fuel starvation issue.

 

[Frank Acampora]

Re: '75 Chrysler Force 75 bad CDI?

Look under the rear of the flywheel where the Cd wires run over the block. Sometimes a wire or two will bounce up against the flywheel and short out, killing the engine. You wait a couple of minutes and the circuit breaker resets. You can then start and run the engine normally until the wires again bounce up into the spinning flywheel.

If this is the problem, re-insulate the wires and put a plate over them secured to one of the CD mounting bolts and the top exhaust cover bolt.

 

[rayeckel]

Re: '75 Chrysler Force 75 bad CDI?

Look under the rear of the flywheel where the Cd wires run over the block. Sometimes a wire or two will bounce up against the flywheel and short out, killing the engine. You wait a couple of minutes and the circuit breaker resets. You can then start and run the engine normally until the wires again bounce up into the spinning flywheel.

If this is the problem, re-insulate the wires and put a plate over them secured to one of the CD mounting bolts and the top exhaust cover bolt.

Thanks Frank! I will try that. I have jiggled the wires leading up underneath the flywheel from the voltage regulator while the engine is running (and all other wires too) and have not experienced it die or notice a short. that said, I did not look to see if those wires would/could 'bounce up against the flywheel".

Also I should mention that I was testing voltage at the circuit breaker when the engine died, and voltage there was good, also I bypassed it completely to rule it out and the problem persisted. Thoughts?

I love that pic you have as your avatar! Where could I see a larger pic of your motor? I have an affinity for vintage vehicles (I drive a '72 Chevy C10 and own a '65 Harley Sportster along with this boat)

 

[Frank Acampora]

Re: '75 Chrysler Force 75 bad CDI?



There ya go! Click on the photos to enlarge them.

The boat is a '71 Glastron V153. The engine is late '70s,probably around 1978. The lower unit is a later dual exhaust from the early to mid '90s but I change lower units more than most people change underwear.

 

[rayeckel]

Re: '75 Chrysler Force 75 bad CDI?

View attachment 215766View attachment 215767View attachment 215768View attachment 215769View attachment 215770

There ya go! Click on the photos to enlarge them.

The boat is a '71 Glastron V153. The engine is late '70s,probably around 1978. The lower unit is a later dual exhaust from the early to mid '90s but I change lower units more than most people change underwear.

Nice! thanks for the pics. I'll bet that little Glastron really gets moving!

What are your thoughts about CDI's going bad? do they just die completely, or can they get hot and fail?

Thanks.

 

[Frank Acampora]

Re: '75 Chrysler Force 75 bad CDI?

If you want to see it running: Youtube Chrysler 125 with a 120 crankshaft. It gets close to 50.

The usual mode of failure for the Motorola CD box is a complete loss of spark and failure to start, Occasionally, they will get a failed internal transistor with resultant multiple sparks and again, failure to start. They usually do not fail gradually.

 

[rayeckel]

Re: '75 Chrysler Force 75 bad CDI?

So, here is an update, for the sake of someone who might be reading this because they are experiencing a similar problem. After triple checking all connections and even swapping out the coil, I convinced myself that I had eliminated all possible culprits other than the CD box, so I went to ol' faithful Captain Mac's Marine here in Austin and talked to Mac about my dilemma. He (of course) had several old Chryslers on property, and offered me an original off of a motor that the cowling had been kept on. Skeptical about spending close to $200 on a really old used electronic part, he offered it to me for $170 with 60 days return. So I bit, and I am happy to say that my outboard has been running like a bat-outta-hell ever since!

Captn' Mac didn't have too many good things to say about the after market CD box that was on my motor (it was on it when I bought it a little over a year ago, and the guy I bought it from told me that it was pretty new at the time.)

So, if you are experiencing the issues that I describe above, and you have exhausted all other options, but are on the fence about spending the cash like I was, then it might be worth it if you have one of these:




Try to find yourself an original, which looks like this:



I was even able to use the new after-market coil that I bought with the original CD box. There was an extra black wire coming out of the CD box, and I just ran it to ground.

Here is a pic after her new paint job:

 

[rayeckel]

Re: '75 Chrysler Force 75 bad CDI?

Another:

View attachment 230965

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