How To: WUR (Warm Up Regulator) CPR (Control Pressure regulator) rebuild kit

[nkemp]

I don't think it should be shorted to housing ground. But housing ground probably shares the ground with the circuit via chassis common ground. So one pin should read zero as measured to chassis ground.

I should have been more clear. The sharing chassis ground only applies if measuring with the plug installed ... A very unlikely scenario.

If unplugged, and if you are getting a short indication between a pin and the WUR body, then it is likely that the internal wiring is shorted to the case or heater assembly and that's a problem needing repair. As I recall, the wires are Teflon insulated and as such using a similar wire is advised but harder to find). An option might be using a piece of plastic adhered to the WUR's inside wall, to insulate between the exposed wire and the WUR.

But it may also be shorting to the heater assembly. Heat shrink tubing "may" be an option. I've seen slide on insulation used in products like coffee makers that can withstand heat that may be an option. But that requires taking apart broken appliances until you find it ... :-(

Time to take it apart and see what's going on.

[Bitsyncmaster]

Mine has the 20 Ohms across the pins. The issue is one of the pins is a direct short to ground. Would that be correct?

Mine runs like crap for a mile in the summer, then good. In the winter, it runs like crap for 10 miles. I have the heater unplugged because it would make a relay hot. I have allready rebuilt mine, but my kit had nothing for the heater.

The heater should not have a connection to the case. Open the cover in the WUR and you will see a wire has burned off the insulation and is touching the case. This is not a rare problem. Mine also had this problem. The wires are Teflon insulated and that insulation is very thin and wears through with vibration if it is touching the case. Move the wires from case if still intact and use some high temp silicone to hold them in place.

[nkemp]

And as I understand WUR operation, you have two unrelated issues:
1) The electrical short
2) Improper WUR operation (crappy running until the engine warms from combustion heat)

Fixing #1 will not fix #2 (unless by chance reassembly fixes the #2 fault).

[Bitsyncmaster]

And as I understand WUR operation, you have two unrelated issues:
1) The electrical short
2) Improper WUR operation (crappy running until the engine warms from combustion heat)

Fixing #1 will not fix #2 (unless by chance reassembly fixes the #2 fault).

The WUR heater power also drives the lambda relay. So that shorted WUR heater may be preventing the lambda relay from working. It also puts a heavy load on the RPM relay (fuse #7).

[nkemp]

Years ago, someone created a bunch of drawings including this one. I find them easier to read than the whole car schematic. Copied here FYI ...

[nkemp]

The WUR heater power also drives the lambda relay. So that shorted WUR heater may be preventing the lambda relay from working. It also puts a heavy load on the RPM relay (fuse #7).

Referring to the previous reply's attached diagram ...

- If it is shorted on the yellow side of the WUR resistor it should fault the #7 fuse
- If it is shorted on the ground side of the WUR resistor, doesn't it simply relocate the resistor's ground?

Or is the diagram incomplete?

[Helirich]

I should have been more clear. The sharing chassis ground only applies if measuring with the plug installed ... A very unlikely scenario.

If unplugged, and if you are getting a short indication between a pin and the WUR body, then it is likely that the internal wiring is shorted to the case or heater assembly and that's a problem needing repair. As I recall, the wires are Teflon insulated and as such using a similar wire is advised but harder to find). An option might be using a piece of plastic adhered to the WUR's inside wall, to insulate between the exposed wire and the WUR.

But it may also be shorting to the heater assembly. Heat shrink tubing "may" be an option. I've seen slide on insulation used in products like coffee makers that can withstand heat that may be an option. But that requires taking apart broken appliances until you find it ... :-(

Time to take it apart and see what's going on.

Yea, it?s measured with the plug off. I have lots of aircraft wire. It?s Teflon insulation. I guess I need to take it apart again.

It?s not really a problem with it unplugged during the summer. I have a mile of dirt road till I get to pavement. I don?t hardly push the pedal during that mile because of dust. It is usually good to go at the end. But now I have to drive on the pavement to get it warm. Very embarrassing for those first couple miles.

[Bitsyncmaster]

Referring to the previous reply's attached diagram ...

- If it is shorted on the yellow side of the WUR resistor it should fault the #7 fuse
- If it is shorted on the ground side of the WUR resistor, doesn't it simply relocate the resistor's ground?

Or is the diagram incomplete?

That fuse #7 never seems to pop. I've seen a few of the WUR heater wires burned so that fuse did not protect it. That is the reason I fused that second RPM relay output with a 3 amp fuse.

[nkemp]

Move the wires from case if still intact and use some high temp silicone to hold them in place.

This is one thing I like about the forum and DeLorean community .... learning ideas I hadn't thought of. Thanks Dave

[nkemp]

So much for the WUR & hunting theory. Today it hunts (~500 - ~1500RPM). Yesterday it was spot on. I wish I could read its mind.