WUR rebuild ?

[Skytrooper]

I have been having a problem with my '76 2.7L 911. At cold start-up the idle RPM drops off to virtually nothing while the engine hunts. This causes a lot of smoking which is a bit embarrasing and probably isn't very good for the motor either. Today after it quit, I unplugged the connector on the WUR. It fired right back up and ran terrific. I am supposing that this would most likely point to the WUR itself as the culprit. I am sure that some brave pelicanites have pushed the envelope and rebuilt their WUR. I am considering it myself and wanted to know if anyone had any tips.

Thanks

[boyt911sc]

Originally Posted by Skytrooper

I have been having a problem with my '76 2.7L 911. At cold start-up the idle RPM drops off to virtually nothing while the engine hunts. This causes a lot of smoking which is a bit embarrasing and probably isn't very good for the motor either. Today after it quit, I unplugged the connector on the WUR. It fired right back up and ran terrific. I am supposing that this would most likely point to the WUR itself as the culprit. I am sure that some brave pelicanites have pushed the envelope and rebuilt their WUR. I am considering it myself and wanted to know if anyone had any tips.

Thanks

Matt,

A lot of guys have done this WUR rebuilt project. Before you get into it, make sure you have a CIS fuel pressure gauge kit handy. Without knowing the control and system pressures of your system, you'll be doing a lot of guess work and might turn out to be unnecessarily expensive.

Here are some intial tips to consider:
1). Check your control and system pressures both cold and warm conditions.
2). Do not mess around with your 'air mixture setting' at this time. Have it checked using a gas analyzer.
3). Look for air leak/s (vacuum) sources.
4). There are more CIS components to inspect that will follow.

Don't forget to check ignition and timing, sparks, etc. Once you have sorted these specs, you'll have a healthy CIS engine. Keep us posted.

Tony

[Paulporsche]

There are many threads on WUR issues so you have some searching ahead of you. I have a particularly long, and to some, boring, one that hits most of the problems.

Aside from what Tony said above, one of the most important things to check is the operation of the bimetal arm within the WUR. That is what actually varies your control pressures.

The WUR is a pretty simple device. It is easily dis- and reassembled. It can also be made to easily vary the cold control pressure. The warm is not quite so convenient, but is easy enough to do.

[T77911S]

i would not go and pull it apart just yet. i suspected my fuel distrubutor for years but something kept telling me to keep looking. i found a bad injection line.

what you did does not really make sense. what connector did you unplug, the electrical connector on top of the WUR? if so, that would continue to make it run rich and continue to surge, not make it run better. it may have just been a coincidence that it ran better, perhaps power was applied long enough to lean it out.

if the idle is low when cold, check the aux air regulator. that should open when cold to raise the idle then after a minute or so it should bring the idle back down. this may be your problem.

check the fuel pressures first. both cold and fully warm. if the FP's are good, check timing, reset mixture, change plugs and give it another try.