1977 140 hp has weak spark all cylinders

[denebach]

I checked all the coils for correct resistance of about 300 ohms. I am not sure of the voltage I should get from the power pack to the coils. My stator and tb wires all read the correct resistance. I replace the power pack with a CDI brand and still get low spark travel and none with the 7/16 inch gap tester. Battery is fully charged. Reds 12v + at the engine terminal strip.

The engine stalls when in the water when putting it into gear. Runs fine on the hose. What should I look for next?

 

[Daviet]

Re: 1977 140 hp has weak spark all cylinders

If you go to the CDI website and look up your engine, they have a troubleshooting section that might help you out.
You say the engine runs fine on the hose and stalls in the water, what do you have your idle speed set at, 700-750 warmed up and in gear?

 

[phillnjack2]

Re: 1977 140 hp has weak spark all cylinders

I would have another check on those coils, if they are original they have probably had their day and the
wire covering starting to perish.
my friends engine is the very same year and model and we have found that the wiring is definitely on the way out.

check it running in the dark and watch it all light up like a Christmas tree, then you can see what needs to be changed.

hope this help a bit

 

[denebach]

Re: 1977 140 hp has weak spark all cylinders

I would have another check on those coils, if they are original they have probably had their day and the
wire covering starting to perish.
my friends engine is the very same year and model and we have found that the wiring is definitely on the way out.

check it running in the dark and watch it all light up like a Christmas tree, then you can see what needs to be changed.

hope this help a bit

I had preiously replaced the coils for that reason. a bad coil will read between 1200 and 2000 ohms. I am contacting CDDI with their specs.

 

[boobie]

Re: 1977 140 hp has weak spark all cylinders

Have you checked your stator output with the correct meter ??

 

[James R]

Re: 1977 140 hp has weak spark all cylinders

I have had many instances where the plug wires on the older motors have corroded and that caused the similar problem. If you have at least one new wire try it and see what the spark is like.

 

[denebach]

Re: 1977 140 hp has weak spark all cylinders

Have you checked your stator output with the correct meter ??

I am not sure what would be a correct meter. Is there a god one that is reasonable in price and fairly accurate?
Would you measure with AC or DC scales? The books call for a neon tester, any suggestions for that?

 

[Bosunsmate]

Re: 1977 140 hp has weak spark all cylinders

I am not sure what would be a correct meter. Is there a god one that is reasonable in price and fairly accurate?
Would you measure with AC or DC scales? The books call for a neon tester, any suggestions for that?

DVA tester, its explained in the cdi troubleshooter.

 

[boobie]

Re: 1977 140 hp has weak spark all cylinders

DVA tester or peak reading volt meter.

 

[emdsapmgr]

Re: 1977 140 hp has weak spark all cylinders

If you have weak spark on all cyls, it's unlikely (but possible) all 4 coils are bad at once. You have replaced the pack. I'd start the ignition testing by looking to measure the stator's cranking output and go from there. The CDI website will show cranking values for this engine: cdielectronics.com. You'll need to rent, borrow the tester boobie mentioned in the above #9 comment. Probably looking for a minimum of 150 volts output. Less than that and it should be replaced.

 

[denebach]

Re: 1977 140 hp has weak spark all cylinders

I went through the CDI test procedures and found the power pack to be according to there specs. I found that most all DVA meters read RMS values and that for a sine wave, not pulses. Peak voltmeters are vary expensive. My stator disconnected, lights up a 120/240 volt neon tester. Connected, I get no lights so I assume the stator can not deliver enough power to the pack. I will replace the stator.

 

[Bosunsmate]

Re: 1977 140 hp has weak spark all cylinders

Just wondering if you disconnected the kill circuit to check that?

 

[danthemanx07]

Re: 1977 140 hp has weak spark all cylinders

I went through the CDI test procedures and found the power pack to be according to there specs. I found that most all DVA meters read RMS values and that for a sine wave, not pulses. Peak voltmeters are vary expensive. My stator disconnected, lights up a 120/240 volt neon tester. Connected, I get no lights so I assume the stator can not deliver enough power to the pack. I will replace the stator.

Did this fix your problem? I am having similar difficulties.