Not enough spark

[ElephantPrint]

My Datsun has been running good, but all of a sudden one day it didnt want to start. It trys to start but it seems as if its out of timing. I checked all timing marks and everything and it all checks ok. I check one spark plug at a time and all are not producing enough spark to start a combustion. Any help?

[Suspect]

If you are running a points distributor, I would look over the point gap / dwell.  The plastic rubbing block wears down causing the points to not open as far or not at all.  I've never really had any luck cleaning the point contacts but you can try.  Also check inside the distributor cap for corrosion on the terminals and possibly the rotor button.  I have found in my years of driving Datsuns, points are just not made like they used to be.  I've had them short out shortly after they were new, had them not run at all new out of the box, some last, some don't.  I usually buy the cheapo ones and that could be part of the problems I've run across.

 

The one problem I had that caused me the biggest headache trying to figure out was when the power wire that runs from the outside of the distributor to the inside to the point wasn't making good contact.  I spent two weeks scratching my head.

 

If it has an electronic distributor, I myself don't know how to help you as I've never messed with one yet.

[ElephantPrint]

My spark plugs, wires, points, cap, rotor, and condensor are all new, my wire from the outside distributor is making contact, when i turn the engine with the cap off the contacts open and close and produce a spark. When i check a spark plug one at a time they all produce a very small tiny spark and the fuel just tends to foul them. All spark plugs are gaped at 0.32, could my ignition coil gone bad now or my ballast resistor? Do you know what the ohms resistance should be for the ignition coil?

[datzenmike]

Points making a spark isn't really enough. The gap should be checked and set at 0.022"

 

If the ballast resistor were bad it would start while cranking but quit the moment you let the key back from the start position to the run position. Know of no failed factory coils, is this a stock coil?

 

 

Check or improve your connections. Is the distributor firmly grounded or is the set screw loose from setting the timing? Are the wires connections to the points firm and tight. Plugs should be the factory recommended NGKs. Pull the plug and coil wires off and look up inside to see if the brass contacts are still there.... are they firmly seated?

[DanielC]

"when i turn the engine with the cap off the contacts open and close and produce a spark."

The points should not spark.  The condenser if good, should briefly "absorb" the spark, and then the energy from the collapse of the magnetic field is directed to the spark plugs.

Datsun point distributors have an external condenser.  Is it there?  It is a small round can.

In this picture, there are two condensers, on the distributor.  There is a small condenser under the distributor, it has the yellow wire, and a larger one on the side of the distributor, with the black wire.

[bonvo]

"when i turn the engine with the cap off the contacts open and close and produce a spark."

The points should not spark.  The condenser if good, should briefly "absorb" the spark, and then the energy from the collapse of the magnetic field is directed to the spark plugs.

Datsun point distributors have an external condenser.  Is it there?  It is a small round can.

 

In this picture, there are two condensers, on the distributor.  There is a small condenser under the distributor, it has the yellow wire, and a larger one on the side of the distributor, with the black wire.

 

this is incorrect only the dual point distributors have external condensers single point have them under the cap

[ElephantPrint]

My coil im guesing is factory and has never been replaced, does anyone know what ohms should resistance be? So the points gap should be at 0.22 and the spark plug gaps be at 0.32 right? Every connection that ive checked is firm and tight. Everything is new except the coil and ballast. Also my distributor doesnt have external dual points, my engine is an A14

[racerx]

Go on autozone or oreillys and seet item details on their website and should give your ohm reading. Good luck..keep us updated.

[racerx]

maybe this will help...not sure if your part of their forum but maybe good idea to join them too.

 

http://datsun1200.com/modules/mediawiki/index.php?title=Ignition_Timing

[I'm BLUE]

this is incorrect only the dual point distributors have external condensers single point have them under the cap

On a slightly different direction 240z single point dizzy condensers are externally mounted.

I can't confirm or deny rest :)

[datzenmike]

 So the points gap should be at 0.22 and the spark plug gaps be at 0.32 right? Every connection that ive checked is firm and tight. Everything is new except the coil and ballast. Also my distributor doesnt have external dual points, my engine is an A14

 

Clean and set the points gap.

 

Make sure your battery is fully charged. A run down battery will have less voltage at the coil when cranking.

Motor cold, pump gas several times. Take top off air filter and look down. Is the choke set?

[ElephantPrint]

My battery was a little drained, ill recharge it today and check it out later today. My choke is set.

[banzai510(hainz)]

you ck if your charging good?

put a volt meter on it

[racerx]

Battery should read 14.5 volts across pos. and neg when car is running, could be lower if RPM is low.

[ElephantPrint]

My battery is fully charged, but wont start due to weak spark. I pulled the plug wire that goes from the ignition coil to the rotor and put a spark plug in it and checked if im getting spark which starts out as a strong spark but becomes weak. Battery is good all ignition components check ok even the gaps. Could it be a bad ignition coil? Ive heard that a coil going bad will cause a low intensity spark.

[racerx]

Go on autozone or oreillys and seet item details on their website and should give your ohm reading. Good luck..keep us updated.
 

Have you done the above? mentioned earlier. Need to know resistance reading before you ohm it out.

[datzenmike]

Strong... weak... it's all very relative. It's........ possibly, the coil. Anythings possible but they don't often fail. A good points system coil should be able to fire across a 3/4" air gap. If you can get this I would say the spark is good.

 

My spark plugs, wires, points, cap, rotor, and condensor are all new, my wire from the outside distributor is making contact, when i turn the engine with the cap off the contacts open and close and produce a spark. When i check a spark plug one at a time they all produce a very small tiny spark and the fuel just tends to foul them. All spark plugs are gaped at 0.32, could my ignition coil gone bad now or my ballast resistor? Do you know what the ohms resistance should be for the ignition coil?

 

Try disconnecting the capacitor and try again. A bad one could have been put on that just now failed. Won't cost anything.

[Suspect]

What is your voltage reading to your coil and power wire on the distributor?

[dr.feltersnatch]

i would try hot wiring it. that will tell you if you are losing power in the wiring. just grab a scrap of wire and run it from the positive (hot) side of the battery to the positive side of the coil. give it a crank and see if it fires. if it does you know its a wiring issue. and be forewarned if it does fire it wont shut off until you remove that wire.

[datzenmike]

May be better to connect to the ballast resistor. This will eliminate all wiring between the battery/ignition switch/ and to the coil. If there is a voltage drop there, this will eliminate it.

[banzai510(hainz)]

is this points ignition?

Another guy just swapped a condensor

[datzenmike]

Try disconnecting the capacitor and try again. A bad one could have been put on that just now failed. Won't cost anything.

 

Yeah, when everything checks out this is one thing left.

[ElephantPrint]

Yes i have 12 volts to the coil and yes its a points ignition. So you guys are saying to by pass or hot wire it straight to the positive side coil or to the ballast and that would give me some juice to fire it up and will let me determine bad wires is what i have, that sounds like a brilliant idea i am going to try that tomorrow and let you guys know.

[banzai510(hainz)]

If you have 12volt to the coil no need to bypass as your key is already doing it.

you need to ck the the ground is switching .

 

I would just take the center coil wire and place near the chassis and when starting see if its sparking. If yes and its weak I dont know what to tell u.

 

maybe the hotwire(START wire ) is loose . or better yet it works and when key goes back to ON then you loose spark. If this is so I would clk the ballast resistor connection or ohm it out.

 

 

if you replace a coil make sure to oder one from the year of car it needs it. not cause you have one lying around and its FREE,they need to match up.

[ElephantPrint]

Yes DatzenMike got it right, i had and extra part which is a condensor so i replaced it and it fire right up. But i hav a new problem my datsun wont stay running unless i pull back the choke, and i try to turn the idle mixture and it seem to not help at all to raise the RPM. Does anyone know what might cause that?