My Datsun truck wont rev up

[Datsun1]

What does that mean

 

[datzenmike]

I think you said it was replaced. Well it could be anything but seems like it was replaced with the correct distributor.  Helps to know this.

 

Make sure the distributor is well grounded.

 

Need those voltage measurements.

[Datsun1]

It was the one that was in it it was rebuilt my dad thought it may nothave been fixed right what are the measurements

[datzenmike]

On 8/17/2018 at 5:22 PM, datzenmike said:

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If it idles when the lights are on then it still works but if the voltage to it is lower the output will be also. It takes less spark to idle that when revving up. Get a meter and see what numbers you are getting between the battery positive and ground...

 

engine off.

engine on

engine on and headlights on

 

Now try the same but between the coil positive terminal and ground.

engine off.

engine on

engine on and headlights on

 

Something is odd here. Unplugging the fusible link shouldn't make it run better. I'm guessing when the lights are turned on the voltage at the EI module drops and it won't rev up.

[Datsun1]

When the fusiable link is plugged up it'll just idle but if its unplugged it kills the truck. What is the EI module??

[Datsun1]

Sorry I left out when the lights is on in the beginning of that

[datzenmike]

48 minutes ago, Datsun1 said:

When the fusiable link is plugged up it'll just idle but if its unplugged it kills the truck. What is the EI module??

 

On 8/16/2018 at 10:26 PM, Datsun1 said:

My 1978 Datsun truck has had timing fixed new distributor and plugs and plug wires it wont rev up just idles thought it was the transistor box because when unplug the fusiable link it runs perfect but if you mess with the lights and stuff it either kills it or makes it just idle the alternator is good I just can't figure it out plz help

 

Well that's different from your first post. Or maybe punctuation would have helped.

[Datsun1]

It only idles or trys to run but back fires with the fusiable link plugged up. With the fusiable link plugged unplugged it runs perfect , until you turn the lights on it kills it. If you do turning signals it starts to miss and backfire. Same with hazard lights

[datzenmike]

Again sounds like the voltage drops when lights are turned on and this affects the module's output. Every thing passing through the module has to get to ground so make sure the distributor case is well grounded. Measure the +12 volts at the coil with the lights off and when they are on.

 

 

[Datsun1]

What is the module?

[datzenmike]

In your case, the box under the dash. On the later matchbox it's been miniaturized down in size and mounted on the side of the distributor. 

 

Being electronic, it's susceptible to poor power supply. When the supply drops below 12 they start to act up. I'm suspecting that turning on the lights upsets the voltage to your EI 'unit' and it craps out.