It's the anti fouler
It's the anti fouler
You probably know this but those are old technology for an engine that burns oil. Anti-foulers thread onto the end of the plug. They move the electrode and ground strap out of the chamber so carbon doesn't build up on them. How did the plugs fail? Were the ground straps burned off? Ends of the plugs blue or discolored? Ceramic insulators around the center electrode cracked or broken?
I learned long ago, the hard way of course, that you have to go two to three heat ranges colder to make the plugs last with anti-foulers. I overheated a plug so hot that the center of the plug ejected itself from the engine. It started with misfiring and popping, and I didn't have the experience to realize what was happening was that the poor plug, glowing red and approaching critical temp, was igniting the fuel before the spark was applied. I just kept downshifting, trying to get to an exit to get off the interstate. All of a sudden there's this "Pop! Fwaa Fwaa Fwaa" sound. I thought I'd blown the engine!
Anyway, good find.
The old plugs looked fine, just carboned up. It was running ok so I took it to an offroad park last fall, played all day and had to limp back to the trailer cause I couldn't keep it running, part of it was the dirty air filter( PO's sock around air filter was clogged up, no filter), and the left side not firing properly. These plugs were 46's .035gap, book says should be 43s. I put 43's in it.
I'm planning on compression test, and leak down test this weekend to see where this little motor sits. See what it has planned for me.
What was really funny was when I was trying to diagnose the dead bank I put the pickup for the timing light on each of the plug wires. By watching the light I could tell #2 was firing erratically, #4 wasn't firing, and #6 would fire once in a while. As my wife would say "Weird".
Wiring question. I have my schematic drawn up for the dual ECM's but I have 1 wire that I don't know where it goes. On the fuel pump relay, the normally closed circuit has an orange wire that is labeled "fuel pump test". Where is the fuel pump test terminal?
Does the engine visibly burn oil? If not then my guess is that one bank of the carburetor runs rich. One way people try to combat carbon fouling is to go one heat range hotter on the plugs. That engine is three ranges hotter and it still needed anti-foulers. Something is definitely up.These plugs were 46's .035gap, book says should be 43s. I put 43's in it.
The test terminal allows you to power the pump directly. It should have a female terminal and it just hangs out of the harness.On the fuel pump relay, the normally closed circuit has an orange wire that is labeled "fuel pump test". Where is the fuel pump test terminal?
Craig, By chance are you going to post a picture of that schematic? I for one would like to see it.Originally Posted by Willys43
The even bank is burning oil.
EDS, I just started a new thread under EFI write-ups. "Odd Fire TBI", I posted pictures of the schematic there. Its in two pages inputs and outputs, some things kinda fit in both categories so you may see an input or two on the output page. I had it all on one page but it was just too cluttered. Hope you can follow it.
Craig
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