Initial Start-Won't Run-Ignition?

[smurfbus]

Did you press the CO screw when turning it? The engine sounds healthy/good so thats a big releif for you.

Now you just need to get the afr right.

[1979-930]

So if I'm watching the second video correctly the throttle body is closed and you can get the engine to run by pressing on the air plate.
Pressing the air plate is controlling the fuel flow to an air inlet system that should be providing no air, or very little, with the throttle body closed.
So the throttle body has a massive air leak or the intake manifold has a massive air leak and you are just compensating the fuel flow for the engine to run.
When the car dies does it backfire or pop in the exhaust or intake?

[H/O Driver]

UPDATE
I removed a shim from the FD and reduced system pressure to 6.6 bar.
It didn't change the Control Pressure.
Still wouldn't run on it's own w/o me pushing down on the metering plate.

I started pushing the plate fast and slow and the piston is certainly following because I can feel it come back down and "slap" the arm when I quickly close the plate. During this, I noticed that the force I had to use to hold the plate open was quite a bit, and thought that it would be too difficult for intake air to pull the plate down on its own. So I bled off the fuel pressure from on top of the piston by disconnecting the line that comes from the WUR. When I pressed on the metering plate now, it was MUCH easier.
So I connected my fuel gauge back up to this line going to the FD but left the other side that would normally attach to the WUR disconnected and feeding into a can. My intentions were to manually control the control pressure with the fuel gauge valve to prevent pressure from building up on top of the piston. After a few attempts, I was able to operate with a lower control pressure and the car ran on its own! It could now pull the metering plate down on its own.
So the 3.3 bar of control pressure is way high. I'll have to see it to believe it, but I think the spec of 2.6-3.0 bar is going to be too much, but....
Chime in please with your thoughts, but now I need to figure out how to adjust my WUR to lower the control pressure.

[H/O Driver]

...I guess I should also verify I have no restriction in the return line. All the lines, filters, etc are new, but maybe a screen or something just inside the fuel tank?

[Alan L]

Your cold pressure is too high = lean engine.
You need to fix that first. Then see how it runs. Not exactly a simple fix - pull WUR apart, or knock the pin, or send WUR out - I think Brian (Rarely L8) does them.
The system pressure won't fix the CP, but it was out of spec and you have an engine not running right. Get everything in spec first (eliminate the possibilities) then see what issues you have.
Alan

[RarlyL8]

As you Alan and others have pointed out the fuel pressures are out of spec.
What FD do you have, -016?
What WUR, -022?
I know what Larry does when rebuilding as I use him and his genuine Bosch parts myself. Don't know what parts were replaced in your WUR, where they came from or what spec was set to when completed. Given the CCP the engine will struggle to start and run. Once the engine is warm it should run but may be lean. Having high system pressure can be compensated with high WCP, but not 10% high. The '76 air meter assembly is unique with the adjustment screw being internal. That can be a bit tedious to work with. Is that what you have? I'll see if I can find a picture.

[Alan L]

It is possible he has a big airleak - as previously suggested - pinched IC O ring or similar. But regardless, the thing needs to get back to spec either way - then see what arises. Can't really test for an airleak when engine won't run - other than pressurise the system - I go via the rubber elbow.
Either that or get things back to spec and hopefully better running then chase the other gremlins - idle mix, airleak etc.
Alan

[H/O Driver]

FD is an -016 I believe. Kind of hard to tell since Larry painted it.
l

Tony said my old WUR (-054) was not fixable, so he did one up for me. It looks like it's a -033. Allen screw on the top rear. Is that for adjustment?



Recall when I opened up the fuel return line, I could get the CCP down and the air meter would more easily operate. So I thought that maybe I had a blockage. I disconnected the fuel return line at the FD and could blow through it (bubbles witnessed in the tank), but it wasn't very easy-it took some diaphragm. Should this be very easy to blow through? Could this small about of back pressure cause the CCP to be high?

Hoping I may have freed something in the line, I measured CCP again and it's still high.

[Alan L]

That allen screw is a mod - allows you to adjust Cold pressure - as I was referring to earlier -'knock the pin'. That has had an adjuster fitted to the pin. Adjusting the CP just got a whole lot easier - for you. I can't remember which way it goes now. And that mod is a slightly different variation of what I have done - so I am a bit loath to tell you what to do with it. But basically that allen screw is fixed in to the pin and allows you to pull/push the pin very slightly. The pin is fixed in the WUR body - you want to mess with it the absolute minimum. Tweek it once ideally - not up/down/up/down/up/down.
I think you need to knock the pin down to drop CP - but wait til someone who actually knows, chips in.
Alan

[RarlyL8]

-033 WUR is for mid 1970's 3.0L 911 not 930.
If the WUR was rebuilt and adjusted to 930 spec it wouldn't need an adjustable CCP screw.
If the adjustable screw works you can loosen the nut and lower the allen head bolt until the desired pressure is reached. That doesn't do anything to help the WCP however.

[H/O Driver]

Ok. Gonna contact Tony and see about adjusting the WUR.

[RarlyL8]

You'd been better off with the -054 as it is a 930 WUR and will enrich the mixture under boost. The -033 will not, so no extra fuel on boost. There is no such thing as an unfixable WUR, you gut the housing and replace it with all new. Anything less is not a full rebuild.

[boyt911sc]

Originally Posted by H/O Driver

Ok. Gonna contact Tony and see about adjusting the WUR.

Bob,

I got your email about this thread. I hardly come to this forum (930) and read this thread. First, I would like to call your attention that the WUR you sent me for rebuild was a WUR-022 not a -054 as you stated in post #28. They are completely two (2) different types of WUR. I still have your old WUR on my work bench.

The condition of your WUR-022 was so bad due to heavy corrosion. The heater was crumbling and with missing internals. The bottom or lower housing was so pitted that it won’t seal and hold vacuum. I spent many hours trying to make it to work but to no avail. It would take so much effort to make this WUR work as it should. So I decided not to rebuild it just to make money.

Then you asked me if I could provide you with a replacement WUR for -022. So I informed you that WUR-033 was the same as your old WUR-022. The only difference between the two (2) WUR’s is the stamped numbers outside the housing. All the internal components are the same.

I went to look at my logbook and reviewed the calibration numbers. As a matter of fact, you have a copy of the spec sheet for WUR-033 calibrated using the -016/-022 Control Fuel Chart. Something is not right after reading your posts. I am leaving for Europe in 2 days and have no time to investigate it. I will be back by August 6 and if you send this WUR back to me by August 7 or later would be great. It is almost 4:00 AM now and could not get this thing out of my mind. I will call you later this morning. Thanks.

Tony

[H/O Driver]

Hey Tony, not too worried about the stampings and changing over to a different WUR. You were upfront with me on this and I was OK with a different WUR built to operate the same as the stock one. If my research is correct, I believe the -022 was for the Euro spec 930's and the -054 was for US versions. How much swapping at the factory, who knows.
My question is the conversion for the adjustment that is on the one you made for me. Do I simply screw it in or do I have to loosen it and tap it down to decrease the pressure?
Shoot, I'm still not convinced it is the WUR even. There is some back pressure on the line going back to the tank. Is there a spec on that? It takes some effort to blow back through mine.

[T77911S]

if the CCP and WCP are correct it should at least run.
the 033 will enrich the mixture BUT it will just do it much earlier than the correct WUR. the 033 works off of vaccum, not boost. that is once vacuum drops to a certain point it WILL lower the CP. so it may not run right when getting on boost.
the other thing is I don't know if the diaphragm would be strong enough to handle the boost.

your mixture could be way off.
check for air leaks,

[boyt911sc]

Originally Posted by H/O Driver

Hey Tony, not too worried about the stampings and changing over to a different WUR. You were upfront with me on this and I was OK with a different WUR built to operate the same as the stock one. If my research is correct, I believe the -022 was for the Euro spec 930's and the -054 was for US versions. How much swapping at the factory, who knows.
My question is the conversion for the adjustment that is on the one you made for me. Do I simply screw it in or do I have to loosen it and tap it down to decrease the pressure?
Shoot, I'm still not convinced it is the WUR even. There is some back pressure on the line going back to the tank. Is there a spec on that? It takes some effort to blow back through mine.

Bob,

I replaced your WUR-022 with an identical WUR. If I place a tape over the ID number, you can not tell or identify which is which because everything inside and out, including the housings are the same. But the WUR-022 is more expensive than WUR-033 because it was designated for 930 application.

Second, WUR-022 operates completely different from WUR-054 (enrichment is done by the boost). We could get to the detail later.

I am a little bit distracted at the moment because a family member just passed away this morning about 3 hours ago. And we are leaving for Europe in 2 days so there is a lot of discussion going on now.

This is what I like you to do for me:
1). Measure the cold control fuel pressure with the just the 2 fuel pumps running (engine off) and WUR electrical plug disconnected. Test run the FP’s with the pressure gauge attached. This test will only need several seconds to confirm the cold control fuel pressure.
2). Repeat the above test but the return line from the WUR is disconnected and open to atmosphere. Install appropriate fuel lines to collect the fuel (gasoline) during the test. You need just a few seconds and read the gauge and shut it off.
3). If the cold control fuel pressures for the above tests are both high, the WUR is the culprit.

The high CCP you are getting could be the result of restricted return line. We don’t know this until you test and confirm it. If the WUR turns out to be the problem, send it back to me so I could investigate it. I will be back by August 6. The family made a decision a moment ago to proceed with the trip. Schedule the package to arrive on or after August 7.

Had I known earlier about your problem, we could have tested it accordingly. Thanks.

Tony

[H/O Driver]

I re-tested the WUR this evening with the goal of removing any doubt about back pressure to the tank. The cold control pressure was 3.25 bar. When I disconnected the outlet, it stayed the same. Temperature was 26C.
Based on comments here, I started to get concerned about adding vacuum and boost.
When I pulled a vacuum (10”) on the WUR, the pressure increased further to 4.0. I didn’t have anything handy to apply pressure to simulate boost. Now the workshop manual does NOT have a spec for fuel enrichment under boost for the ‘76 and ‘77 models like it does for the ‘78 and later models, so I’m not sure how enrichment is done on boost.

[RarlyL8]

If your engine is stock and you would like to retain top value and optimum performance you need the -022 WUR. If your engine is modified I would suggest having a Bosch shop rebuild your -022 and putting it in a box for the next guy then install a -054 or similar unit from a 3.3L turbo.

[Alan L]

Your cold pressure looks way too high. 90+% chance your issue is the WUR and the settings.
Will leave to Tony to sort - otherwise we will all be jumping over top of him.
Alan

[H/O Driver]

OK. Talked to Tony. He wants me to send him the WUR. I'll report once I get it back, installed and tested. Sounds like it will be around mid August.
I think I will obtain a -022. Let me know if anyone has one.

Thanks for everyone's help so far!

Bob