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12 volts..33 ohms internal resistance...it ain't pulling much.. .36 amps
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Ron:
I'm curious as to what the amperage is when warmed up. Applying V=IR to the WUR and AAR yields a lot of amperage...how could the headlights ever get powered? I wonder if the contacts in the WUR drop it out at a certain temperature or resistance, for example, when the engine is warmed up? Did you see the same contacts in the AAR? Maybe it's like the toaster in the kitchen. Next time I bring the car to work, I'll stick the Amprobe on the WUR circuit |
that diagram above is for the original 73/74 WUR which does ground through it's case. there is only one terminal on those.
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Pat, Thats was .36 amps. I think all my dots......confused the issue.
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Ron:
Yes, you are absolutely correct...I confused myself. The element would thus be on the range of 4 watts Pat |
If a properly functioning setup is only supposed to pull .33 amps, then there's something seriously wrong somewhere in Pkaaso's setup for it to be able to melt the insulation. I don't think we'll know anything until someone measures the voltage going in to his WUR, and then measures the amount of amps his WUR is pulling.
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Agreed, Also since the AAR is on the same circuit it too should be having issues..unless the coil is open.
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Melted insulation is pretty much an indication of a short somewhere. I ended up rewiring my entire engine compartment, 14 pin and 6 pin connectors, and taking out a bunch of no longer used circuits.
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You Bet! As soon as I get the replacment WUR, I will investigate these issues before the SMOKE TEST...
It is a stock 81' with original motor. I checked running voltage seems normal 13+ low, med, and high RPM's. If alt is over charging (high amperage) it's strange that the WUR is the only casualty. Thanks to all for reading and all the input. Maybe I just keep getting crappy WUR's.... Just my luck ;) Quote:
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OK guys. I just opened a 81' .090 WUR. Using a meter, one of the wires DOES ground to the case. In this WUR one wire goes directly to ground the other goes to the center tap of the heating coil. So, it absolutly maters if the wires are switched.
Paul |
By-the-way...
Thanks for all the input. If after I correct the wires, install the fresh WUR and the car goes down the road... Woo Hoo!!! |
Hah, now it makes sense :) glad to hear you got it figured out, and now we've all learned from it too. Have a good one!
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OK, explain why that makes sense! If 12 volts mistaken goes to the case and then to ground you would have no voltage going to the heating element. Am I missing something here ?
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Quote:
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Maybe, I misunderstood I thought that the element was cooking. Party on
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Originally, the problem was internal short in the WUR, I believe. If the wires were reversed in polarity at the terminal to the WUR, you would get zero heating, as there would be no flow of electrons in the heating element. The wiring would melt because of the short, but the WUR heating element should suffer no damage, I would think. I agree with Ron on this.
I would like to find out about the center tap function. It may be some sort of cut out. Pkaaso, did you get that thing working yet? |
Today
Hey all,
Just got the fresh rebuilt yesterday and had to get a new terminal repair kit. So, nope, not yet. Got busy but hopfully this weekend I'll get a "Round-Tu-It" and see what happens. I am very sure that this is the problem. To add... The first two WUR's did in fact warm and change fuel pressure as normal per Bosch for a little while. But, did suffer burned/melted wires after time. I think the heating element did get warm even with the reversed wires. Remember it's a 3 tap element. I don't have a schematic on this. Anyone have a drawing of the 80+ WUR's... ? Paul |
If I can chime in here, here's a data point. From what I've noted on several WURs, those heating elements that have a single winding on the heating element, that is, only two electrical connections, there is no ground to the case of either end of the element. For elements that have a double winding, i.e., three electrical connections, one end of the winding is grounded to the case. An 072 and a 090 WUR are examples of these that have one end grounded. This facilitates the extra bimetallic strip in the WUR that acts as a thermostat in conjunction with the second winding on the heating element.
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