Ignition demons

[danielcookson]

New here. I recently bought a 1971 521 and working at sorting it out. The previous owner dropped a ton of cash into this thing and just got tired of it. New radiator, gas tank, shocks, tires, brakes, basically everything except the body.

 

Initially it ran fine then gradually became harder and harder to start. It has the weber conversion and dual point distributor. On a recent trip out of town it was impossible to start so I took it to a shop. They replaced the starter (i cranked the new one I had in it to death), cap, rotor, points & condensor, and coil. It ran great and started every time no problem. Now after less than 1500 miles it started getting harder and harder to start and now it won't start. I replaced the points and condensor just to play it safe, even replaced the coil since it was under warranty. After checking the ignition system I found that I get spark at the distributor but not at the plugs. (the shop checked the distributor and said it was fine).

 

I am at a loss what to do next.

 

Any suggestions? (I want to go electronic ignition but this thing should start anyway)

 

Thanks much.

 

Dan

[moparvwfreak]

Sounds like ya need a set of wires, and an EI dizzy. If forgetting spark at the dizzy but not at the plugs, defiantly need wires.

[ggzilla]

Sell it before you sink a ton of money into it.

 

Or take it to the shop that fixed it before and get their advice. No need to spend money to solve a problem like this, it will be something that cost less than $20 but what it is takes troubleshooting.

 

It could be several things, but most common it either point set, condensor OR gap -- and not all three. Usually just one.

[danielcookson]

Thanks guys. I changed the point sets (boh of them), the condensors (again both) and set the gap at .20. Double checked it so I know its correct. The plug wires are new and I checked the connections on them. I do get spark at the points but not the plugs. I could check this again but was careful since I didn't want to get shocked. The condensors could be bad even though I changed them as new. I am keeping the cost investment low. This isn't rocket science. Electronic Dizzy is the way to go I think.

[ggzilla]

It's a low energy spark. It won't hurt like the late 1970s ignition. Just a bit shocking.

 

 

The condensors could be bad even though I changed them as new.

Yes, indeed. Half a dozen ratsun members went through that this year.

 

For the dual-points, i understand that only one set is needed to run the engine. So you can try swapping the condensor and leave the 2nd set of points disconnected. Someone else can explain which one.

[datzenmike]

I do get spark at the points but not the plugs.

 

 

Pull the coil wire off the distributor cap and stick a spark plug in the end and lay on a grounded surface. Have someone crank the motor over.

 

Spark???

 

1a/ No Spark:

Check that there is voltage on the + terminal of the coil when cranking.

Check that the points are opening and closing (They Must Do Both)

Check that the distributor is well grounded.

With key on briefly touch a grounded wire to the Neg coil terminal... go to 3a/ 3b/

 

 

1b/ Yes there's spark:

Put the plug in one of the spark plug wires and crank it over. Go to 2a/ 2b/

 

 

2a/ No spark:

bad plug wire(s)

bad or mission rotor

bad distributor cap Just because they are new does not mean they are good, take them off and inspect.

 

2b/ Yes there's spark:

it should start

 

 

3a/ Still no spark:

Coil is bad

 

3b/ Now it sparks!

points are not working or distributor not grounded.

[Jayden71]

I had this same problem on my 521 when I got it goin. Kept havin trouble with the points burnin out after just a few hundred miles. Matchbox dizzy with electronic coil......not a single problem 4 years later

[ggzilla]

Or just fix the wiring without having to buy a new distributor... continually burning out points mean a bad coil or incorrectly wired coil.

[banzai510(hainz)]

what GGzilla said.

 

you might have the fire order wrong.

 

Hot start wire hooked up. ballast resisitor wired correct?

 

this is a SIMPLE

 

 

hard to start? Tighten intake. You have gas? valave lash adjusted. Timmed. ?

[danielcookson]

Thanks for all your help. Let me recap. When I first bought the truck it started fine and ran fine. After about a month and a couple of thousand miles it began becoming very hard to start. Then I did something stupid. I took a 350 mile one way 3 day trip. After arriving I couldn't get the truck started the next morning. I took the truck to a shop and they 1)replaced starter because I fried it trying to start it 2) replaced the coil since they said it was bad 3) replace points, condensors, cap and rotor. The truck started and ran great. Now a couple of weeks later and back home the truck isn't wanting to start. I replaced the cap, rotor, points, condensor, and even swapped out the coil since it was covered on warranty. Replaced everything the same way it was before. The only thing I haven't done is change out the plugs and wires. They were new when I got the truck and still look good. When the engine turns over there is spark at the points, but not at the plugs. i'll try King rat's suggestion and report back.

[danielcookson]

I had this same problem on my 521 when I got it goin. Kept havin trouble with the points burnin out after just a few hundred miles. Matchbox dizzy with electronic coil......not a single problem 4 years later

 

 

So can you tell me about your dizzy upgrade? I can buy the 79-80 620 Dizzy from Autozone or O'Reilly Auto Parts. Did you use your "L" shaped adjuster plate and aluminum dizzy pedestal or did you get from the junk yard. Can I use the one on my truck or will I need to source another adjuster plate from a L20b engine from a yard? Thanks much.

[DanielC]

If you are using the points distributor, if would be best to have a stock coil. The points can only switch a smaller amount of current, and if you put a "high energy" or even a coil designed for a car without points, the additional current may over loads the points, and thay go bad pretty quick. By the way, even with then original stuff, Datsun recommended checking the point gap, and timing every 3000 miles, and replacing the points every 12,000 miles.

 

If you get a matchbox distributor, it is almost necessary to get the pedestal that goes under the matchbox distributor, and the steel plate between the distributor, and pedestal. It is also a really good idea to get the coil for the matchbox distributor too.

 

If you buy a new matchbox distributor from an auto parts store, it is hard telling what you may have to do. I did use a matchbox distributor on a 1970 L-16, on the l-16 pedestal. I had to do some cutting and welding on the steel plate, because the matchbox distributor is larger diameter.

[banzai510(hainz)]

Simple fix

Key is use the correct stock coil and ballast resisitor. Dontr just put any coil in the truck, They are ohm specific for that model truck.

 

Ck for spark. Once you got spark make sure the fire order correct.Take center coil wire place near chassis and hit the starter. wire should be about 1/8 inch to 1/4 and should be good snapping spark.

ck the valve lash

Ck the intake carb for loose bolts.

Then ck for gas in the carb ck or see if fuel pump works(remove the output hose and crank the motor and gas should shoot out.

pump/cycle the linkage see if gas is shooting in the carb if not then start looking there.

[Jayden71]

I moxified my L16 plate to fit the matchbox dizzy. I too bought my dizzy from auto parts store. It has given me zero provlems

 

[Tweeker521]

Same thing on mine. Only one point was firing so I hot wired the other in. Replaced the coil, new wires, new condensers, new feasible link, now I only get spark when I let go of the key

[ggzilla]

Never replace what aint broken. New wires?

[banzai510(hainz)]

Tweeker

now I only get spark when I let go of the key ????????????

 

thats means your HOT START is not working .

Have you ck the wires going into the ballast resisitor and out the otherside to the +side coil???????

 

PS on dual point systems the main point only works untill the 3rd gear switch is used then the duals work if I remeber right. if I used a dusal point I wouldnt even use the 2nd set anyways. I dont know how you WIRED it in.

 

I really dont know How a simple sytem can be changed to work better.

 

 

521s have a fusable linK??????

[ggzilla]

Yes, the coil needs TWO wires from the ignition switch, the Run wire via resistor and the Start wire. If you connect it wrong it won't spark while cranking but will begin sparking as you release the key.

 

I really dont know How a simple sytem can be changed to work better.

By using EI, it is much simpler. Doesn't need resistor. Doesn't need points. No condensor to go bad. Simpler to set static timing even. The wires inside the EI distiributor don't get loose and short out sometimes like they do on points distributor. The newer ignition switches don't even need two wires to power the coil.

[ggzilla]

521s have a fusable linK?

521 was the last Datsun to use the old fashioned wiring. Even the 510 added a Fusible Link in 1970.

 

521 has on positive cable, black wire direct to Fuse Box, On starter terminal, thick white to alternator, thin white to voltage regulator.

No Fusible Link, so if any of those wires short out, it can start a fire. It doesn't happen very often, but we've seen burnt wiring harnesses.

[BlueDat]

holy threadbump batman! my 521 is doing this - turns over but I hear no gas & sparky go bang bang bang until i stop cranking - and with a keyless gutted switch. I guess somewhere along the line it's not wired right or happy with something. changing over to a 4 lug universal start switch, I would assume that IGN1 and IGN2 will be combined for this thing to be happy. it's like the engine isnt "getting out of it's own way" upon startup till i stop trying to crank, and it takes off. 

[datzenmike]

You hear no sparky? Better to pull a plug wire off, stick an old plug in the end and lay on a grounded surface and crank. This is the only way to know for absolute certain that there is or isn't spark when cranking.

 

 

 

The run wire (Black/White stripe) on the 521 goes to the ballast resistor and through it to the coil. This allows running at about 8 volts and does not burn the points out as fast.

 

In the start position, the above is true AND there is a power wire (Black/Red stripe) around the ballast to the coil. This gives full 12 volts to the coil for extra high voltage to the plugs during cranking.

 

When the key is released it returns to power through the ballast only. In either case it should fire up even if one wire isn't working.

[BlueDat]

got spark, but after crank in only the on position. runs like it has a miss, and the PO apparently had trouble with points burning up. 

 

they cut the acc wire and had the Start and Ign 1 spliced together, obviously they had B+ happy and Ign 2. 

 

I am changing the wiring AND the stock plug out, it's all crusty and the terminals are crap, 

 

what I propose is:

 

B+ for B+, instead of ACC , IGN 1 , IGN 2 to IGN , then start. goes to a 4 wire just not using the acc of the truck for the radio which is just a hole in the dash for now. will go with a more correct plug and switch when they become available. 

 

sound right ??

[BlueDat]

they wired the starter onto IGN2 and the b/r wire is not hooked up at all. geez. installing breathalyzers for a living is paying off dealing with this circuit abomination LOL dropping dashes and soldering and finding the right wires all day. i need a beer....