WUR short circuit, replace WUR?

[Kevin]

Hi all,

I seem to have a short circuit in my WUR. If I start the engine with it plugged in, my #7 fuse blows. From what I've read, it's somewhat common.

My question is, do I have to replace my WUR, or is it something relatively easy to fix if I open it up?

Kevin

[NightFlyer]

Hi all,

I seem to have a short circuit in my WUR. If I start the engine with it plugged in, my #7 fuse blows. From what I've read, it's somewhat common.

My question is, do I have to replace my WUR, or is it something relatively easy to fix if I open it up?

Kevin

Technically, the WUR/CPR is a non-servicable part, but it can be taken apart and rebuilt. If it's just a loose connection, no problem. But if you need to replace some internal parts, I have no idea where you would source new parts from, other than a pulled junkyard unit.

http://www.jtresto.com/e21/WURServicing.pdf

Hopefully someone with better info than I have chimes in with some help :smile:

[DMCMW Dave]

Hi all,

I seem to have a short circuit in my WUR. If I start the engine with it plugged in, my #7 fuse blows. From what I've read, it's somewhat common.

My question is, do I have to replace my WUR, or is it something relatively easy to fix if I open it up?

Kevin

You can take it off and carefully open it up. I say carefully as you don't want to tear the gasket. There are some small parts (springs and a linkage bar) that can fall out, so open it upside down so they stay where they belong and you can get it back together. You'll see that the internal heater wiring has probably melted and is shorted to the case. You can fix the short (insulate it) and probably be OK. The other failure is that the heater burns out, but that won't cause a short, that will just cause it to act like it isn't plugged in at all.

The tricky part is making sure that the plunger ends up in the right place.

Quite honestly, if you leave it disconnected you'll probably never notice the difference. The warm-up cycle will run a bit long, which means it will be a bit too rich until the engine is fully warmed. In a warm weather climate you won't feel it, in a cold climate you'd have a problem passing an emission test if the car is not warmed up for a long time. The more important functions of the regulator are mechanical, and the heat from the engine will eventually get it to the right pressure.

If you are nervous about opening it up, you'd have to get a replacement.

[Kevin]

Thank you, NightFlyer and Dave!


Quite honestly, if you leave it disconnected you'll probably never notice the difference

I'll probably end up going this route in the meantime, then. I was seeing if fixing my WUR connector (which had a wire cut, now I know why) would fix my problem of the engine being bogged down when cold (http://dmctalk.org/showthread.php?6752-Bogged-under-load-after-cold-start). I guess my next step is to test the thermo vacuum switch, as recommended in the thread there.

Thanks again!

[Bitsyncmaster]

The internal wiring is Teflon insulated wire. Teflon is very thin and not good at abrasive cutting. So if the wires were touching the case, they can and do end up shorting. Just open it up, move the wires off the case and use some high temp RTV to hold them off the case.

I'm surprised your fuse blew. More common is the wires burn open. Think the long 19 AWG wires connecting that circuit are just to small to blow the 20 amp fuse. I added a three amp fuse on my car for that circuit. My car the WUR wiring inside the unit burned open and did not blow the 20 amp fuse.

[Kevin]

The internal wiring is Teflon insulated wire. Teflon is very thin and not good at abrasive cutting. So if the wires were touching the case, they can and do end up shorting. Just open it up, move the wires off the case and use some high temp RTV to hold them off the case.

I'm surprised your fuse blew. More common is the wires burn open. Think the long 19 AWG wires connecting that circuit are just to small to blow the 20 amp fuse. I added a three amp fuse on my car for that circuit. My car the WUR wiring inside the unit burned open and did not blow the 20 amp fuse.

I guess I was lucky! I've got your solid state RPM relay on that circuit too, I was afraid for its fate while I was investigating, thankfully it survived.

Yes I saw your post during my research about fusing your WUR, sounds like a good idea, I might have to do that once I fix/replace my WUR. Here's the post, for anyone else interested: http://dmctalk.org/showthread.php?940-Fusing-your-WUR-(CPR)

[David T]

If you are squeamish about trying to fix it, SpecialT can "rebuild" it and calibrate it.