Stumped on WUR

ninelevenick · 01-15-2007, 09:32 AM

I have a '79 SC and I recently purchased a CIS gauge and modified my WUR to make it adjustable. Before modifying, I had been experiencing a minor cold start issue where the engine wouldn't fire up right away and the idle would surge a bit. Otherwise, it ran great. After modifying the WUR, I put it back in the car and hooked the gauge to it. System pressure is almost 5 bar, which according to my Bentley is normal. However, even with the plug knocked pretty far in, I can't get over 1 bar on the gauge. My question is could the WUR have blockage? I tried forcing air through the inlet where the screen is and I would think that air would come out the other orifice, but nothing came out. Also, from what I understand, I connect the valve side of the CIS gauge to the larger orifice (the one on the bottom of the photo with the screen). Is this correct? Thanks for any help that you can give me. I have a photo of my WUR. You can see my modification and the larger orifice is what I plug the gauge into.

RarlyL8 · RarlyL8's Garage

Knocking the pin in will decrease the presure and richen the mixture.
What was your cold presure when you started?
The gauge goes in between the outlet on your WUR with the screen and the outlet on your fuel head.

ninelevenick · 01-15-2007, 09:51 AM

Good. I've been connecting the gauge correctly.
When I first started, I think the cold pressure was around 2.5 to 3 bar. Then thinking that the pressure would increase as the pin goes down further, I took another measurement and it was below 1 bar, which makes sense according to what you are saying. However, while the gauge was still connected to the WUR, I pulled the plug up, but did not see any change in the pressure.

ninelevenick · 01-15-2007, 10:41 AM

I got the cold pressure around 1.5 bar. Started the car, but it took quite a few turns of the key for it to fire up. A lot of small backfires out of the exhaust. It will not idle smoothly and I have to stay on the gas or else it will stall out. Any ideas?

Oracle · 01-15-2007, 11:06 AM

I saw my mechanic forcing air into each of the orificies and air came out thru the other one, I asked why? and he said it's healty to blow them clear...

ninelevenick · 01-15-2007, 11:14 AM

Hmmm. I also sprayed carb cleaner into both holes. The cleaner just welled up in the holes instead of flowing into one and out the other.

john walker's workshop · 01-15-2007, 11:16 AM

before messing with that unit, be sure the hot CO is around 3.5% first, and the timing is correct. i start the WUR around 1bar cold. if the engine surges up and down, pull the pin out until it stops. if the engine spits and pops when it's revved up, sink the pin a tad. keep the electrical plug disconnected while you do this, and do it quickly so the engine doesn't warm up while the WUR just sits there cold.

ninelevenick · 01-15-2007, 01:45 PM

Thanks for all the replies.

I had the CO and idle professionally adjusted about ten months ago and I have not messed with it since. Without changing anything from my last failed attempt, I started the car again and this time, it actually idled pretty well, almost as well as it did before modifying the WUR. Most importantly, it drives without surging and bucking. I'm leaving it like this for now because I am tired of messing with it. Current cold pressure is at 1.5 bar with temperatures around 10 degrees Celsius. I think what was happening is I was over zealous in knocking the plug and pulling it back up. Small increments!