930 running rich, very loud rear engine compartment noise

[wcarson]

Hi everyone,

I hoping that someone here can help me solve an issue with my 1982 930. The car is a 3.3L car still running CIS injection. The Fuel distributer, WUR, and AAV were all rebuilt or replaced when I rebuilt the motor 20 years ago and the car has been driven about 5,000 miles since then. I know, not enough. It's been a wonderful car and I try to at least start it and drive it around once a month a bit. Sometimes it sits though for 2-3 months without being started. I know, I know, I need to drive it more.

The fuel pumps run on this car when I turn the ignition to the on position, it's always been that way. Thus when I start the car, I need to quickly turn the motor over so as not to flood it. If it floods, then I simply pull out the fuel relays and burn the extra fuel off before starting the car again. Again, it's always been this way and I'm used to this.

This weekend, when I tried to start the car it was making a very noisy metallic whine sound from the rear motor area. I got under the car and it is definitely not the rear fuel pump. It's definitely not the CD box either. The motor ran, but idled poorly and produced a huge amount of white smoke- it appeared to be running very rich. I pulled the airbox and intercooler off to help determine what is making the noise and I can't quite pin it down. It seems to be coming from the fuel distributor area, but I can't tell for sure. I can't imagine a bad injector making this sound, but that thought crossed my mind.

Here is a youtube link to a video that I took. This is with the ignition ON, fuels pumps running, but the motor NOT turning over or running. As you can see- this is very loud.

https://www.youtube.com/watch?v=v9ubmcjOrTA


Anyone have any ideas???? THANK YOU in advance!! I'm going to also post this on the 911 forum here on Pelican, since there are many more 911's running CIS than 930's.

[smurfbus]

Are you sure you have gas? White could be water from empty tank? The sound ismystery if not rear pump. Possibly air pumped if empty tank? Accumulator noise figting to pressurize air?

[pkabush]

I’ve never heard that either. Accumulator does seam plausible.

[wcarson]

Hi guys,

Thanks so much for the input. I definitely have fuel. I am hoping it's something easy like a stuck injector.

I'll need to test all the fuel pressures if the injectors looks good. I've done all the testing years back and will need to review how to do it- I do have a factory service manual that goes through the procedure.

I'll also pull the plugs out and crank the motor in to prevent hydrolock in case one or more cylinders is full of fuel.

The noise is definitely not the rear fuel pump. I put my ear right up to it and it's making the appropriate humming/whine sound.

Thank again!

[full quack]

The very ending "squeal" that is heard, sounds exactly like when the inlet pressurized fuel into the fuel heads is being stopped by the metering plate seating into the closed position.
I have heard the exact same sound (although not so loud), when I have manually pressed down on the metering plate and then manually released it slowly (pumps on & running).
So maybe your fuel pressure has skyrocketed due to WUR diaphragm failure.

Massive amounts of unburned fuel that has been atomized can display a white cloud, but will also engulf you with the smell of gasoline, do you smell gasoline when it did that?

Mark

[wcarson]

Originally Posted by full quack

The very ending "squeal" that is heard, sounds exactly like when the inlet pressurized fuel into the fuel heads is being stopped by the metering plate seating into the closed position.
I have heard the exact same sound (although not so loud), when I have manually pressed down on the metering plate and then manually released it slowly (pumps on & running).
So maybe your fuel pressure has skyrocketed due to WUR diaphragm failure.

Massive amounts of unburned fuel that has been atomized can display a white cloud, but will also engulf you with the smell of gasoline, do you smell gasoline when it did that?

Mark

Indeed it was pretty strong smell of fuel. I think I will need to check the pressures. Thank you for the input.

[DSM]

Sounds like fuel distributor control plunger is stuck open. Best thing would be to have it cleaned or rebuilt if needed. Then go thru entire fuel system. For a quick cheap fix you could try adding fuel additive to gas tank then remove all injectors and place in containers. Then turn fuel pumps on and push down on sensor plate. This may free up whatever is binding up plunger.

Be very careful when working with fuel that's under pressure.



Important notes:
Right now with fuel injectors installed you are most likely flooding the engine with fuel every time fuel pumps are energized.
Change engine oil / filter before running it after fix.

Control Plunger video(Precise mechanism):
https://www.youtube.com/watch?v=fZ0sOhPlNrY

Fuel Additive:
https://www.amazon.com/Liqui-Moly-2007-Gasoline-Injection/dp/B00CPL8PSG/ref=asc_df_B00CPL8PSG/?tag=hyprod-20&linkCode=df0&hvadid=312168100217&hvpos=&hvnetw=g&hvrand=10592966494849461406&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=21180&hvtargid=pla-569061980879&psc=1

Cleaning link for ref:
cleaning out cis fuel distributor

[smurfbus]

Fuel pumps running does not mean they are squirting all the time unless the plunger is stuck open. Its easy to check removing one injector from IM. Best to remove all and measure the flow at the same time.

[mark houghton]

Originally Posted by smurfbus

Fuel pumps running does not mean they are squirting all the time unless the plunger is stuck open. Its easy to check removing one injector from IM. Best to remove all and measure the flow at the same time.

Correct. In fact the injectors should not squirt at all until the engine is cranking and pulling in air/deflecting the metering plate and opening the plunger.

Similar problem with mine that I've just lived with. My plunger is probably slightly gummed up or whatever, and won't completely close the fuel delivery ports when the metering arm is at rest as it should. I can hear the injectors squeal as soon as I turn the pumps on, and must start the car without delay or risk flooding.

[donbecker1234]

One idea I'd throw out, the OP is saying that it always floods if the engine isn't started quickly.

Could this be a stuck open injector?

I'd pull all the injectors and get them tested first to rule them out.

[wcarson]

Hi everyone-
Thank you all so much for your input.

One quick question for you all: Can I make a determination if the plunger in the fuel distributor is stuck when the distributor is in the car? Right now, my airbox and my intercooler are off. When I move it up and down manually, the sensor plate operates very very smoothly and does not bind and seems as smooth as silk. Looking at the schematics, I am assuming this means the plunger is operating and moving in and out smoothly with the sensor plate movement?

As for the pumps and injectors running when the ignition is on- this is something the car has always done both before and after my engine rebuild. When I did the rebuild, the FD was fully rebuilt by Stephen Kaspar (Imagine Auto back in the day), the WUR was replaced with a brand new unit, all new Porsche Bosch injectors were put in, the AAV was replaced, etc, etc. So that's not related to this current issue.

Before I completely pull everything apart and start from the ground up restoring and refurbishing the entire CIS system, I am going to try to isolate the noise more and hope to find an isolated problem.

Thank you all again for your expertise and knowledge!

[RarlyL8]

Cars that sit suffer all of these maladies. If fuel is allowed to evaporate anywhere in the system it can leave deposits that reek havoc. Movement of the mechanical parts also keeps them properly lubricated and free of deposits. The grease on the air meter fuel piston leaver will harden over the years which can affect response time. Pulling the fuel injectors and placing them in jars will allow you to operate the system and see what is going on at the injectors. The plate can be manipulated manually and you can check function. Be sure to put a battery tender on the battery to keep voltage up during testing.

[wcarson]

Originally Posted by RarlyL8

Cars that sit suffer all of these maladies. If fuel is allowed to evaporate anywhere in the system it can leave deposits that reek havoc. Movement of the mechanical parts also keeps them properly lubricated and free of deposits. The grease on the air meter fuel piston leaver will harden over the years which can affect response time. Pulling the fuel injectors and placing them in jars will allow you to operate the system and see what is going on at the injectors. The plate can be manipulated manually and you can check function. Be sure to put a battery tender on the battery to keep voltage up during testing.

Hi Brian-

So if the sensor plate manually moves up and down smoothly, does that mean the plunger is NOT stuck? Or will the plate mechanism still be able to move up and down manually if the plunger is stuck in a depressed position in the fuel distributor?

Thanks for weighing in. I've read so many of your various posts over the years. We've never met or communicated before, but I'm a follower of yours! I run a dual in dual out M&K on my 3.0 carburetted 1970 911T.

[stevie 77 930]

All that has been said about the sensor plate, i certainly agree with. While i noticed that your fuel head does shut off after pressurizing, I would start by backing out the fuel mixture screw so there no chance the screw is keeping the sensor plate in an open position. Pulling the fuel head off to check the plunger isn't difficult, (a short stubby screwdriver is required) My guess is that you may be experiencing low system pressure on start up, checking your system pressure can verify this.

[smurfbus]

I would not touch the CO adjustment screw if no changes were made with it. Easy to get it so wrong nothing makes sense.

[full quack]

Hello wcarson,

"When I did the rebuild, the FD was fully rebuilt by Stephen Kaspar (Imagine Auto back in the day), the WUR was replaced with a brand new unit, all new Porsche Bosch injectors were put in, the AAV was replaced, etc, etc. So that's not related to this current issue."

Unfortunately, your above quoted statement means absolutely nothing anymore, as too much time, too much car sitting idle and too little driving of the car has happened over the past years.

These cars and systems really, really hate sitting stagnant, and fail due to this neglect.

When I bought my car it had only 30K miles on it, but had sat for 3 years without being started or driven. In the end, I replaced, rebuilt or discarded many, many parts until she finally behaved herself.

Furthermore, never forget the accurate old adage "just because it's new, doesn't mean it's any damn good".

Mark

[wcarson]

Originally Posted by full quack

Hello wcarson,

"When I did the rebuild, the FD was fully rebuilt by Stephen Kaspar (Imagine Auto back in the day), the WUR was replaced with a brand new unit, all new Porsche Bosch injectors were put in, the AAV was replaced, etc, etc. So that's not related to this current issue."

Unfortunately, your above quoted statement means absolutely nothing anymore, as too much time, too much car sitting idle and too little driving of the car has happened over the past years.

These cars and systems really, really hate sitting stagnant, and fail due to this neglect.

When I bought my car it had only 30K miles on it, but had sat for 3 years without being started or driven. In the end, I replaced, rebuilt or discarded many, many parts until she finally behaved herself.

Furthermore, never forget the accurate old adage "just because it's new, doesn't mean it's any damn good".

Mark

Mark,

I totally agree with you that all these parts that were new are no longer new. And it's very bad for the car as a whole (especially the CIS!) to sit for prolonged times. As for my statement:
As for the pumps and injectors running when the ignition is on- this is something the car has always done both before and after my engine rebuild. When I did the rebuild, the FD was fully rebuilt by Stephen Kaspar (Imagine Auto back in the day), the WUR was replaced with a brand new unit, all new Porsche Bosch injectors were put in, the AAV was replaced, etc, etc. So that's not related to this current issue.
My point was that all of these things were originally replaced and rebuilt under my watch 20 years ago and that the car has run beautifully all this time for the past 20 years until this current issue cropped up. During the whole time it has run beautifully, the fuel pumps have always run the second the ignition is turned on. I understand that's not how it is supposed to function, but that's a separate issue from the current issue.

Thanks for the input everyone..... And Merry Christmas to everyone!

[wcarson]

I'm still trying to figure out the answer to this one:

One quick question for you all: Can I make a determination if the plunger in the fuel distributor is stuck when the distributor is in the car? Right now, my airbox and my intercooler are off. When I move it up and down manually, the sensor plate operates very very smoothly and does not bind and seems as smooth as silk. Looking at the schematics, I am assuming this means the plunger is operating and moving in and out smoothly with the sensor plate movement?

[smurfbus]

Remove injectors, put them in small bottles. Ignition on so pumps run , check if injectors spray. If not its as it should. Now press plunger and note it sprays and it stops spraying when you release the plunger.

[ljpviper]

I had a cold start problem on an 89 that was pretty consistent. I am guilty of leaving the car sitting for up to a month sometimes.

About 2 months I made it a point to drive the car at least 30 minutes a week. Seems like the weekly driving cured the cold start problem. These cars are built pretty simple but hate to be sitting you would think the opposite.

Good luck