Odd WUR Problem

JLGarbanzo · 07-06-2006, 09:17 AM

I know there are thousands of posts for WUR problems, but i think i have a somewhat unique problem here.

I purchased the '78 911 last summer knowing it came with cold start problems i would need to diagnose.

Well, this weekend, I finally got the chance to investigate the problem and was pretty convinced i had isolated the problem to the WUR. I unbolted it to take a look at cleaning it or purchasing a new one and, much to my surprise, i found the WUR model didnt match my engine.

The PO seems to have slapped a '78 928 WUR on my car...no wonder there were cold start issues. Biggest problem now is that i dont have a core to exchange.

I talked to John at specialty parts and he offered me $350 for a new WUR in exchange for my non-matching core. im just wondering, is this the best i can do?

I was thinking of trying to find a trashed WUR, buy it, and have it rebuilt. Even if i got a broken WUR for $100, it would still be cheaper than $350 to buy it and rebuild it. At the same time, I also dont want the car to sit in the garage for ages waiting for a part to come my way.

Any suggestions would be greatly appreciated.

safe · safe's Garage

Have you checked the control pressure so you know that is the problem?

RarlyL8 · RarlyL8's Garage

It is not uncommon for the WUR to be replaced by one from another model. They all operate pretty much the same way. What you can do is make the one you have adjustable (using the archived info). That will allow you to dial in the cold start pressure you desire.

JLGarbanzo · 07-06-2006, 09:43 AM

Safe,
I don’t have the gauges to check control pressures. I did go through and methodically check every hose for a vacuum leak. I then went and bought some carb cleaner and sprayed the idling engine to search for leaks I couldn’t see. The idle didn’t really change, so I ruled out a vacuum leak. When I took off the WUR to clean it and found it was the wrong model number, I stopped there.

JLGarbanzo · 07-06-2006, 09:45 AM

RarlyL8,
My concern is that i dont know if the WUR is not functioning properly because it is the wrong model or because it is outright broken.

RarlyL8 · RarlyL8's Garage

If the WUR is your problem it probably isn't broken, it's just old and out of spec with the rest of the old equipment.
You must get a cold pressure reading to diagnose this problem properly.

JLGarbanzo · 07-06-2006, 10:02 AM

I assume i can get a local shop to do it for me?

How much should i expect to pay for it?

safe · safe's Garage

You can buy or make your own fuel pressure guage. But, like Rarly says, you need to check it before doing anything else.

JLGarbanzo · 07-06-2006, 10:34 AM

Bosch CIS Tester?

$198.95?

http://www.pelicanparts.com/catalog/shopcart/911E/POR_911E_TOLtol_pg6.htm#item29

Is that it?

safe · safe's Garage

Yes, thats it.

Doug Steinel · Doug Steinel's Garage

cheaper yet from JC Whitney

JLGarbanzo · 07-06-2006, 10:55 AM

Awesome, i just bought it from JC Whitney, although the website says it wont ship until 7/22.

I wonder if anyone in CT has one i could borrow for the weekend...

safe · safe's Garage

If your a little handy and got the time you build your own for ~$50.

JLGarbanzo · 07-06-2006, 10:58 AM

Would you have the specs for all the fittings?

safe · safe's Garage

Nope. I went to dismantler and looked for a car with CIS and removed a bunch of fitings and fuel lines.
Then I bought a valve, a t-pipe and a guage at the local plumber. It didn't really fit together properly, but I brazed it togerther.

JLGarbanzo · 07-06-2006, 11:11 AM

I just called JC Whitney. The part is on backorder, thats why its going to take so long.

Hmm...I wonder what I could find those parts in CT.

sammyg2 · 07-06-2006, 11:36 AM

I ordered one from JC whitless a couple years ago. After 4 months of back order I told them to forget it and bought one somewhere else.

JLGarbanzo · 07-06-2006, 11:43 AM

Once my system is diagnosed and tuned once, will i need this tool again?

I dont want to invest in a $100-$150 gauge if i am only going to use it once. Would I be better served trying to find someone to borrow the gauge from?

klaucke · 07-06-2006, 11:44 AM

JLG: you can find the CIS parts/fittings you will need at many auto recyclers in the area. You need to look on other model cars: older VW, Saab, Mercedes, Audi, and BMW are all potential sources of CIS parts.

I got my current WUR out of an older VW Golf or Rabbit and made it adjustable using a wideband air/fuel meter instead of the CIS guages. It cost me less than $10 and only a little of my time.

JLGarbanzo · 12:00 PM

klaucke,

The car never ran right from the time i purchased it. Therefore, i cannot conclode that my fuel mixtures are set right. Wouldnt i need a good baseline to use your method to tune a WUR.

Could you elaborate?