No spark.

[joeyk803c]

Ok guys, I have a 72 521 with the L18 motor in it. I've cut out the previous owner's "new" 12 volt wiring job, and started to redo it. I've never had a big issue with the truck starting till last week. I had put two gallons of fresh gas in it, and the truck started right up. No issues. It idled great, and drove great. I used it to reposition my 74 beetle in my backyard. I then parked the truck into the backyard. Well, later that day or the next day (can't remember) a guy came over to look at it. The truck wouldn't start and stay running. It would start up and die out.

 

Fast foward to a couple days ago (tuesday). I again, could not get the truck to start and stay running. I ended up having to keep revving the motor to get the truck to stay running.

 

I went to start it wednesday morning, and the truck wouldn't start. I wasn't getting any spark to the plugs. I replaced both my resistor and coil today. Still no spark. Trucks turns over just fine, battery has 12.3 volts on it. I'm getting 12 volts to the coil.

 

What could be the issue. I believe its down to the distributor. It has a new cap and rotor. Could it be the condensor, or the contacts going out that causes no spark to the wires?

 

 

[datzenmike]

Stick an old plug in the wire from the coil. Lay on a grounded surface and crank engine. Is there spark?

 

Yes... there is something wrong with the rotor, cap or the wires to the plugs.

No spark....  Points not opening or closing

 

 

For there to be a spark the points must open and close. Take the cap off and watch them while cranking the engine over. If worn or eroded... replace them.

 

When at their widest opening, on the high spot on the cam lobe, the gap should be about 0.022" or thickness of a paper match book cover.

[joeyk803c]

I put a old plug in the coil wire to the Distributor, no spark. The rotor does turn. I will be picking up a new condensor and points today. I'll see what those will do. 

[wayno]

OK, try this, take a good size wire with an alligator clip on each end and connect one end to the positive side of the coil, then connect the other side to the positive post on the battery, get in the truck and turn it over, does it start now? 

[datzenmike]

This is a good idea to eliminate the power supply from the ignition switch. If it starts (or at least fires) then the switch is at fault

[wayno]

This is a good idea to eliminate the power supply from the ignition switch. If it starts (or at least fires) then the switch is at fault

It's more than that, the 521 has 2 power sources, one for starting(black/red line) and one for running(black/white line), he stated, " I've cut out the previous owner's "new" 12 volt wiring job", so that could mean that it has no start power wire now.

That wire going directly to the positive side of the coil is easy to miss, as the one needed to run it goes to the ballistic resistor then the coil. 

[joeyk803c]

Its wired right. Its not a factory harness by any means. I've had it running before. Just last week it started up right. I went then to start it later that day after I parked it in the backyard and it didn't want to start.

 

Fuse for the ignition is good. I'll have to go get some clips and see. So it could be the ignition switch too? I have the fuel pump wired so it comes on only with the ignition, and the fuel pump works (its an electric pump), so I don't know why I'm not getting spark.

 

I just put in the new condensor and points and still nothing.

[datzenmike]

Get a $5 test lamp. Ground one end and touch the + coil terminal with the key on. If it lights then there is power to it.

[joeyk803c]

Figured out the problem. Apparently the fine engineers over at BWD decided it was okay to mark the positive and negative sides of the coil wrong. No negative=positive and postive=negative.

 

The new condensor/points made the engine idle horribly rough (it was a weber carb, so that could be tuned too a bit) but damn once I put the old parts back in, the truck starts right up and idles fairly nice.

 

Thanks for all the help guys, I'm glad I just switch the coil around. LOL

[uberkevin]

The little things!

 

Glad you found out what it was man.

Now post pics . :D

[joeyk803c]

I have some on my DSLR I'll upload and then post. Its a major work in progress. Once I finish up the wiring, and get some new tires I'm going to DD it my short 2 mile commute to work, as I work on the truck.

[datzenmike]

 

The coil should still work but the spark would jump from the head to the spark plug electrode rather than from the electrode to ground. So with the old parts back in it runs fine means there never was a problem then?

[joeyk803c]

I think the old resistor went out, and screwed up my coil. I've had bad luck with the damn coil, maybe because of the old resistor.

 

Now it runs. Problem lied with the resistor/coil but that should be fixed now.

[datzenmike]

If the resister is broken it will start while the starter is turning but quit when the key returns to on. You have to have a resister in line with the coil or it will burn up the points and possibly overheat and fry the coil.

 

Is this the stock coil? Because they are problem free. Beware after market coils that draw too much power and fry the points.

[joeyk803c]

No. Its a BWD coil. Its weird. Just through the new coil on, and it runs no. I'll see how to does tomorrow when I do some more wiring work on it.

[bilzbobaggins]

if doing more wiring work on already suspect wiring, tank lots of pictures in case it no workey again.

 

Good Luck

 

Jef

[wayno]

This is a nightmare, I highly doubt this is the end of this issue.

In my entire life of 57 years, I have never heard of a coil being marked backwards.

The ignition switch on a 521 is wired the way it is wired for a reason, when the key is in run mode the power goes to the ballast resistor so the coil doesn't overheat, with the key in the start position, the ballast resistor gets no power, so you can turn it over all day and it will not start when it is cold, when warm you can let off the key from the start position and sometimes the engine will start as it gets power briefly while the engine is still actually turning, this is the reason why the 521 wiring has a start mode wire, when the key is in the start position/mode, there is a black/red line wire that supplies power directly to the coil to get it started, but it is not on long enough to overheat the coil, just long enough to start it.

When a coil overheats, it can cause the engine to run bad, back fire and/or die, once it cools down it may start working again.

You need to wire the engine for the ignition switch assembly you are using, the 521 ign. switch assembly needs 2 wires.

[joeyk803c]

Its an aftermarket switch assembly. I have a fused wire going directly to the ballast resistor, then a wire coming from the ignition switch to that "ignition" fuse block. I believe it is wired so that only in the "ignition" part, the resistor/coil gets power and when in start, it gets no power although I will have to confirm this with a test light tomorrow.

 

Wayno, I appreciate the tips. The coil has been marked backwards. I'll snap a picture tomorrow to show you.

[banzai510(hainz)]

I have wired a coil backed wards and it still ran.

 

key ON will have 12volt to the + side ballast then it goes to the + side coil

the START wire goes to the + side coil . usually on 521it will have 2 wires 1 from the down side ballast to the + side coil.

[joeyk803c]

Sorry its been a while. Truck now starts and even runs. I drive it around the block to get a feel for it. It idles a little weird. Still new to the carb thing. I'm thinking about getting a fuel/air mixture gauge and adding in a wideband 02 sensor after the manifold to see what my mixture is like. Still am working on the wiring (pretty much just lighting wiring now).

 

Here is the pic I promised of the "reversed" pole coil...