Chrysler 1977 135 dies if more than 1/3 throttle

[seattle scott]

Re: Chrysler 1977 135 dies if more than 1/3 throttle

Thanks Nordin. I need to confirm something. When I test the coil lead with the spark gap tester with the motor cranking I geet no spark or just one spark. The diagnostic instructions says " if it fires when you crank the engine over, there is a problem in the distributor . . . ", so a "no fire" is a good result? I would of thought the coil is supposed to fire 4 times ( 4 plugs) for each turn of the flywheel.

Ok I did the white/black wire test,When I did the white/black wire test with the wire connected to the distributor, with key on I got .5 volts and and cranking I got 4 to 5 volts so this is "low" correct? So then I did test with blck/white wire removed and a spark gap tester on the coil and grounded and key on and CDI humming I strike the wire end to ground and get spark each time, indicating the pack is good and I assume the coil also. So I guess I am looking at the preamp - can that be tested?

 

[Nordin]

Re: Chrysler 1977 135 dies if more than 1/3 throttle

Okey, the preamp can not be tested, but when you strike the white/black wire to ground you simulate the preamp (or points if it has ).
SO my thought is the preamp is bad. As I say im my issue with the 75Hp Chrysler. I was a little confused but the preamp can give a lot of issues when it is bad.

BTW measure the voltage at bluewire terminal on the distributer to ground, should be 12VDC. when ign.key is ON all time.
Then measure the white/blackwire terminal and it should goes from 0 to about 12VDC at every cyl. (4 in you case) and 4 times of each revolution at the distributer.
If not..... the preamp is bad.

Maxrules OEM preamp for 100 dollars seems to me a good price.

I do not remember what I paied for my preamp. I bought it from FranzMarine because I bought from him before and had no problem since I am in Sweden Europe and want the shipping and customs go well.

 

[seattle scott]

Re: Chrysler 1977 135 dies if more than 1/3 throttle

Thanks Nordin. I talked to the tech guy at CDI electronics who confirmed that if the black/white wire tapped to ground gets spark, then trigger is bad. I installed a new CDI trigger, got it from Sea Way Marine in Seattle because in stock for about $140. Couldn't get any spark. took plugs out and grounded them, no spark when cranking motor, but as before, when key is released all four plugs fire before flywheel stops. So I did Frank's test with a rope start, but with the plugs out. With key on and all plugs out and grounded when I pull/rope start all plugs fire. Put plugs back in and engine will start when key is released from start position. In other words, crank engine for 10 seconds, release key and it fires and starts. So when starter engaged no fire any plug. Battary is at 12.6 v at terminals, it drops to 11.7 when cranking with choke on but holds there. Blue wire into ignition box 12.5 with key on, drops to about 11.7 when choke engaged. When cranking engine blue wire drops to 10.3 and further drops to 9.6 - 9.8 with the choke engaged. So the ingition system is working, except when the starter is engaged. SO even though I am getting at least 9.5 volts cranking at the blue wire, it is acting as if the voltage is too low and there is observed no spark, until key is released. The CDI troubleshoot sheet says if voltage low, check harness ( But I get 12.6 at blue wire with key on), key switch, starter or battery( the battery only drops to 11.7 when cranking so "I am ruling that out)I can swap key switches to check, but I don't know any check on the starter which spins the flywheel fast.

 

[seattle scott]

Re: Chrysler 1977 135 dies if more than 1/3 throttle

When I add 12v from a separate power source to the blue wire, starts up fine, within a second. So need to go fishing tomorrow, salmon are running. I am just going to put clips on the ends of a wire and connect the battery straight to the blue wire going into the ignition box (leaving the blue wire connected from the harness still hooked up) so I have enough volts into the box when cranking. Then I can unclip from the batt once it starts.

 

[Nordin]

Re: Chrysler 1977 135 dies if more than 1/3 throttle

Okey, check all connections in the hole electricsystem. You have some bad connections, check thick wires (red) at startsolenoid and at the starter.
Check thick groundwire (black) at engineblock and even the thick wire from lowercowling and block.

Maybe you have a starter with carbondust in and/or worn brushers.

 

[seattle scott]

Re: Chrysler 1977 135 dies if more than 1/3 throttle

The weird thing is when I connect a 2 amp battery charger to the blue wire and ground, plugs fire. When I do the same thing using an 80 amp wet cell "car" battery ( in other words a dedicated "ignition" battery not supplying amps to the starter) it won't fire with starter engaged. Well, off to clean/tighten all the connections in the starter circuit.

 

[seattle scott]

Re: Chrysler 1977 135 dies if more than 1/3 throttle

Sorry for the delay in getting back to everyone. Motor runs fine if I can get it started. There is something wrong in the CD module. Specs are that it will fire with as little as 9.5 volts, well it won't fire unless it is getting more than 12 volts and it gets less than 12 volts ( as in 10.5 - 11) when the starter is engaged. So I ran a jumper wire off the blue wire and added another ground wire to the mount bolt on the CD box and then ran these out of the engine hood. It clip these on a 14 volt cordless drill battery, turn key, engine starts and then remove the clips. Since the engine is putting out 13.5 -14.5 volts when running the CD box works fine. Once the fishing season is over in a month, I am going to send the CDI box back and see if I can get some credit on a replacement.

Thanks for everyone's help.