1978 75hp Chrysler No Start 757H8D

["EYE" DOCTOR]

The motor is currently a no start. I launched at the lake and it started fine. I drove a few big circles at wide open and various positions on the throttle. I came down to idle in the no wake and it idled for about 30 seconds and then died. I waited about an hour to get a tow. I tried cranking at about 5 minute intervals but got no start. Once back on the dock the engine backfired and then started and idled for about 10 minutes. I turned it off and then restarted a few times. The last time it restarted it quit about 30 seconds after idleing.

I seem to be getting fuel. The plugs are wet. I don't have spark to the plugs. I have power via the test light on the blue ignition wire at the distibutor. I have no power after that.

 

[Frank Acampora]

Re: 1978 75hp Chrysler No Start 757H8D

You should have an electronic distributor. This distributor has a blue and a white wire terminated on the front of it. Inside there is an electric eye that uses a plastic shutter to signal the CD box to dump power into the coil.

Unfortunately there is no known way to test an electric eye.

However, your no spark condition is most likely due to either a defective CD box or a defective electric eye. Could be a bad coil too though.

Before you get into checking, look at the CD box wires where they pass under the flywheel. Often, they bounce up and contact the flywheel. This causes an AGGRAVATING no spark, intermittant spark condition. So if the insulation is worn off, repair it.

To perform the following tests, be sure the engine has no gas in it and disconnect and ground the unused plug wires. This prevents the engine from starting in your hand.

SO: if you have 12 volts at the blue wire as it enters the distributor, then while cranking the engine by hand with the ignition on, see if there is voltage at the white wire as the distributor comes past the firing point (this signals the CD box). For ease, use the top cylinder since this is #1. If the white wire has voltage ONLY while cranking, then we must assume for the time being that the electric eye is good. NOW, while cranking by hand, check the power from the CD box to the coil. It should only discharge once for each firing point. If there is power only while it comes past the firing point, then we must assume it is good. IF it fires multiple times or continuously, then the CD box is bad.

If all is good to this point, then it is time to check the coil itself. Use an ohmmeter to check for continuity. Check all grounds for broken or disconnected wires.

 

["EYE" DOCTOR]

Re: 1978 75hp Chrysler No Start 757H8D

Before you get into checking, look at the CD box wires where they pass under the flywheel. Often, they bounce up and contact the flywheel. This causes an AGGRAVATING no spark, intermittant spark condition. So if the insulation is worn off, repair it.

I checked this first. I read about it in one of your other posts while searching. The wires are good. Thanks for the correct starting procedure as well.

SO: if you have 12 volts at the blue wire as it enters the distributor, then while cranking the engine by hand with the ignition on, see if there is voltage at the white wire as the distributor comes past the firing point (this signals the CD box). For ease, use the top cylinder since this is #1. If the white wire has voltage ONLY while cranking, then we must assume for the time being that the electric eye is good. NOW, while cranking by hand, check the power from the CD box to the coil. It should only discharge once for each firing point. If there is power only while it comes past the firing point, then we must assume it is good. IF it fires multiple times or continuously, then the CD box is bad.

I don't know what a cd box is but I will find it. The rest sounds just like testing the points in a non electronic ignition. Thanks for the help. I'll try it out tomorrow.

Where would one find these parts if they are bad and what about cost?

 

[Frank Acampora]

Re: 1978 75hp Chrysler No Start 757H8D

I checked this first. I read about it in one of your other posts while searching. The wires are good. Thanks for the correct starting procedure as well.



I don't know what a cd box is but I will find it. The rest sounds just like testing the points in a non electronic ignition. Thanks for the help. I'll try it out tomorrow.

Where would one find these parts if they are bad and what about cost?

The CD (Capacitor Discharge) box will probably be a Motorola CD ignition. It will be a black, finned , aluminum box, about 5 X 6 inches, with the coil attached, mounted on the distributor side of the engine. If by some chance it is a Delta ignition, then the CD box will look different but will be mounted the same place.

You can try for new or used ones at The Chrysler Crew, or specifically, franzmarine@aol.com. Used CD boxes will probably cost around 125. I have heard that they can be rebuilt but it costs the same as buying a new one. I don't know what a new electric eye costs but they are expensive. You can retrofit the distributor to points if the eye is bad. It involves changing the wiring a biy though.

 

["EYE" DOCTOR]

Re: 1978 75hp Chrysler No Start 757H8D

Did some more troubleshooting. I still have power to the blue wire on the distributer. No power on the white. I have no power after the distributer while cranking. I have not tried to crank by hand yet but I will try that next if I need to.

It did start this morning and idled for about 10 minutes. It turned off and restarted several times. I put it in forward gear and let it idle. I put it back into neutral and it idled for a while and then quit. Now it won't start again.

Is there any way to check the cd box with a meter?

 

["EYE" DOCTOR]

Re: 1978 75hp Chrysler No Start 757H8D

Just checked it by hand. I rolled it to tdc and had power to the white wire. The test light lit up on each cylinder. Put the plugs back in and it started. It then stalled. I once again have no power to the white wire and it won't start.

 

[Frank Acampora]

Re: 1978 75hp Chrysler No Start 757H8D

Remove the distributor for ease of working. Remove the cap and check the inside for corrosion at the wire terminals AND the ground for the electric eye. If all these are good, then you must assume that the electric eye is not functioning properly.

Blue wire sends power to the light emitting diode in the electric eye, As the shutter clears the eye sensor, the diode sends light to the receiver and the receiver generates an electrical pulse which signals the transistor in the CD box to dump the capacitor charge into the coil. If the eye ground is corroded or not good, the LED will not send light to the receiver.

SO: if you have intermittent power on the white wire from the distributor to the CD box, then the only thing you can think is that the electric eye is not working for whatever reason.

When you replace the distributor, set the top cylinder to TDC. Set the pulley on the distributor so that the straight line points to the flywheel and the curved line matches the curve of the flywheel.

SNUG the drive belt so that a .010 feeler gauge pointed like a finger at the center of the belt deflects it about 1/8 to 3/16 inch. DO NOT overtighten the belt. To do so will bind the distributor and the engine will either stick in gear or will shift into gear very difficultly

 

["EYE" DOCTOR]

Re: 1978 75hp Chrysler No Start 757H8D

Thanks again Frank. I will try this in the morning. I brought the boat home from the dock today so I can troubleshoot it in the yard. I have been looking for parts online but my cd box is white and I can't find the electric eye on any listing. I'll keep looking it's got be out there somewhere.

On the other hand the dock time is pretty expensive and I've already lost 3 weeks. I may get a Merc from the marina and part out the Chrysler.