When is it a spark plug & when it is more serious????
Posted: Thu Jan 28, 2016 10:02 pm
Hi All,
Thought I would share a little challenge I've seen several times now and again tonight. If you were at the Get Together this past weekend, you may have seen me drive a fresh 502 refurbishment from the trailer. When it idled, I walked away and then just like that, I heard it quit. No biggie I thought as they can be a bit cold blooded.
So I tell people all the time who can't get a Diablo started and are sure they have fuel and spark, to change the plug. If that does not work, change the plug again. If that does not work, change the plug again. I've seen an occasional spark plug foul and if you have a crankcase full of fuel, it will foul another plug without even giving a puff. So after three plugs in this Diablo and it did not start, we pulled it back on the trailer and enjoyed the rest of the day.
In the shop tonight, I got down to it with that red devil. This Diablo would puff and backfire. It had spark. It had fuel. It ran perfect before, it was a screamer before I loaded it on the trailer. I layed in bed last night thinking about it wondering why it was acting like the timing was off. This morning, it popped in my head that the mechanical advance must be stuck. So off came the flywheel tonight and it was not stuck, but I took it off anyway and cleaned up the lever. Put it back together and the same issue.
I know of no good test without the proper equipment to test a condenser or ignition coil. I tell people all the time who want to throw a new condenser and ignition coil in their Diablo just because they want new, that the OEM condenser and coil are darn hearty and rarely, I mean really rarely do I find a bad one.
So out came the ignition plate. I tested the existing condenser and coil against new aftermarket parts with an Ohm meter. Same readings. Same ramp of continuity. It just can't be these parts I keep saying. But I had that sneaky suspicion. So I replaced them, put the machine back together and one pull almost sent it through the wall. I'm just always shocked when I find a bad condenser or coil. In this case, I had spark - good blue spark. But during the initial troubleshooting, I had the plug out and was testing the spark and I noticed just a slight abnormality in the spark. At first I just dismissed it. Now I know the cause.
I really can't offer much guidance on this. Sometimes you just have to take a chance and replace some parts.
Anyone else have any good thoughts on diagnosing bad condensers and coils?
Bruce
Thought I would share a little challenge I've seen several times now and again tonight. If you were at the Get Together this past weekend, you may have seen me drive a fresh 502 refurbishment from the trailer. When it idled, I walked away and then just like that, I heard it quit. No biggie I thought as they can be a bit cold blooded.
So I tell people all the time who can't get a Diablo started and are sure they have fuel and spark, to change the plug. If that does not work, change the plug again. If that does not work, change the plug again. I've seen an occasional spark plug foul and if you have a crankcase full of fuel, it will foul another plug without even giving a puff. So after three plugs in this Diablo and it did not start, we pulled it back on the trailer and enjoyed the rest of the day.
In the shop tonight, I got down to it with that red devil. This Diablo would puff and backfire. It had spark. It had fuel. It ran perfect before, it was a screamer before I loaded it on the trailer. I layed in bed last night thinking about it wondering why it was acting like the timing was off. This morning, it popped in my head that the mechanical advance must be stuck. So off came the flywheel tonight and it was not stuck, but I took it off anyway and cleaned up the lever. Put it back together and the same issue.
I know of no good test without the proper equipment to test a condenser or ignition coil. I tell people all the time who want to throw a new condenser and ignition coil in their Diablo just because they want new, that the OEM condenser and coil are darn hearty and rarely, I mean really rarely do I find a bad one.
So out came the ignition plate. I tested the existing condenser and coil against new aftermarket parts with an Ohm meter. Same readings. Same ramp of continuity. It just can't be these parts I keep saying. But I had that sneaky suspicion. So I replaced them, put the machine back together and one pull almost sent it through the wall. I'm just always shocked when I find a bad condenser or coil. In this case, I had spark - good blue spark. But during the initial troubleshooting, I had the plug out and was testing the spark and I noticed just a slight abnormality in the spark. At first I just dismissed it. Now I know the cause.
I really can't offer much guidance on this. Sometimes you just have to take a chance and replace some parts.
Anyone else have any good thoughts on diagnosing bad condensers and coils?
Bruce