74- Problem with idle

[m5bb]

I am helping a helpless friend get a 74 3.0 CS running again after sitting for 2 years.
He thought there was dirt in the gas.
Opened tank where gauge goes in, clean, clean. Looks like new tank.
Removed fuel pump from block. With a few pumps on the arm had fuel at the carbs.
Fuel was old.
Car would try to start and immediately die.
After checking around with connections I finally got it to start but would not idle. Had to keep pumping the gas to keep it running.
Looked all over for a vacuum leak as that could be the problem.
Could not find anything unless I am missing something?

Opened up fuel tank again at gauge hole and syphoned 95% of gas out.
Put new gas in.
Some better but still same idle problem.
Car warming up and problem not as bad.
Looked at chokes but were not stuck closed and seemed to be open when warmed up.
Pulled a spark plug. Black but not fouled where they wouldn't run. Also not wet as if running rich.
Installed new spark plugs anyway as that is easy and cheap.

I did not know about an idle control valve till I looked at some data on this site. Yeah.
I am not at the car location when writing this so I am assuming that this car has idle control valves.
Can anyone help me with this.
Are they dirty like an idle control valve on a M30 535i might be? Clean with
Throttle body cleaner?
They have a elec connection (re: diagram i found here) I can check for power there?
Are these valves available?
Do you think this is the problem?
I check the cap and rotor and though they aren't great I know that is not the idle problem.
Help would be appreciated.
Gary

 

[MMercury]

I am helping a helpless friend get a 74 3.0 CS running again after sitting for 2 years.

I did not know about an idle control valve till I looked at some data on this site.

You seem to be moving in the right direction. You neglected to identify what type of carburetors you are working with, original Zeniths or the common replacement Webers. Assuming you are dealing with Zeniths, there have been several threads (pictorials) on this board that might help you keep things together. There are also several references that you might consult: http://www.e9coupe.com/tech/zeniths/bmw2/bmw2.html
http://www.e9coupe.com/tech/zeniths/bmw1/bmw1.html
http://www.e9coupe.com/tech/zeniths/haynes/haynes.html

Most of the carbs, including the common Weber 32/36 and 38/38 DGV replacements have an idle shutoff valve. The valve goes by several different monikers, including an anti-dieseling solenoid - whereas it shuts off fuel delivery when the ignition is switched off to prevent run or dieseling, hence the name. (The idle control valve more typically is found on fuel injection systems and controls air volume, similar to the function of a carburetor choke.) Typically, the solenoids need to be energized to permit fuel flow. With the ignition on, or when the solenoids are connected to a 12V source, they should operate. This involves a clicking sound, and if you were to remove and view the operation, a small rod moves in an out to seat and control idle jet fuel flow. Unfortunately, even if an idle solenoid is fully functional does not mean that the jet or internal passages that comprise the idle circuit are not gummed up with fuel residue. The fact the car sat for a lengthy period suggests that this is the likeliest problem.

Per the above, remove the solenoids, determine whether they work and the internal rod moves freely. Next, get your carb cleaner out and with the spray nozzle tube attached, go at the jet and idle circuits. While this may be the likeliest cause of your problem, the long term storage could have caused other issues, e.g., sticking needle and seats, floats that are stuck of possibly half filled with fuel.

Good luck!

 

[adawil2002]

Sitting 2 years = varnished gas, clean and rejet the carbs, replace fuel filter, replace in tank screen, clean fuel pump conical screen, replace fuel lines.

Before it's driven overhaul/service the brake system, check wheel bearings, change oil.

 

[61porsche]

Carbs won't idle

Yes, you need to check for power at each idle solenoid. It is fused. so check for power with a test light or meter. It would be rare for a solonoid to be bad. VW parts appear to be the same and still cheap unlike the BMW parts.

Sat for two years- today's fuel have alcohol which absorbs water. If you want to be certain that no "white rust" has formed in the carbs, you'll have to take the top two sections off and clean out the bowl, float vlave, all the jets. It can be done with the carbs on the motor unlike the repair manual. You'll need some gaskets unless the carbs are fresh.

So let's try the down and dirty procedure not in the manual-

Tighten all the carb screws. Not too tight; just enough to snug them down and a bit more. But I doubt by what you're describing this will help until you get it to idle at least rough.

Raise the idle- use the main screw on the front linkage and watch for the carb arms to move about an 1/8 ". Don't go fooling with the individual carb screws. Those are for after the carbs/ engine can run.

1. Pour several tablespoons of gas down each carb throat to get the thing to cough. Sometimes? this is enough to loosen up the floats which can stick open or closed, the fuel pump to fill the bowls again- 10-30 seconds. So try it several times and see if that smooths things out to idle. ( Pray to the E9 gods.

2. Idle circuit- take off the solenoid- blow compressed air back through where that solenoid is screwed in. Carb spray cleaner. White rust again can clog that circuit. Solenoid's click when powered or unpowered- no click, no good. Tighten hand tight and just a bit more; but no more. Try again.

Look on top of each carb- you'll see the two air jets. Next to that jet closest to the head will be a small hole in the metal casting. That hole is your air for idleing. Not the brass ones. If for some reason the idle circuit is partially plugged and really lean, find a piece of tape (yes, your handyman's duct tape) cut a small square and place it over that hole. What this does is force more fuel rather than an air mix for idle. Start again.

If none of this works, it's carb clean time with something caustic to boil out the circuits. Acetone. Yes, that stuff you buy now at the local auto parts is more environmentally safe, but that won't cut it.

You can pm me if you want my contact info for details. Keep your hammers away from the car.

 

[m5bb]

Great help guys.
You have provided me with a few hours of reading.
Yes they are the Zenith carbs.
Maybe not as bad as it sounds.
All the fuels lines and fuel filter were replaced recently.
Will check the screen in the pump.
Screen in tank was fine.
Did not know about screens at carb fuel inlets.
Mostly going to check the idle system solenoids and jet area as suggested by Porsche 61.
I did spray some cleaner down the carbs while it was running.
I did use the screw that controls the arm to both carbs to raise the idle to 900+ or so to be able to work and check things while running.

BTW this car and some other BMW's are stored in a lower level of a business that is totally climate controlled. Probably better than my house.

Ordering some new points, rotor and cap as well since the current ones are a little ruff.
It will be first of the week before I can get back to this so I will do my homework and get back to you guys next week.
Thanks so much for the help.
Later,
Gary

 

[Stevehose]

Depending on the fuel pump model it may not have a screen. My old one did not. I am not aware of any carb inlet screens on Zeniths. Screw the idle mixture screws in until they stop (gently) to see how many turns they were set at then take them out and blast carb cleaner in there too. Then check their o-rings and replace if cracked (I found some at Lowes that fit) and reinstall at previous settings or start from scratch at about 2 turns out.

 

[61porsche]

Those instructions

are part of the advanced Zenith supplimental training manual! And there were a few steps before experimenting with mixture screws.

First, follow all safety precautions including NOT looking down the barrel of a non working carburator while starting. The dragon in Lord of the Rings had nothing on a sitting E9 when it blows like Moby Dick on the 4th of July.

But if you must proceed, second find, borrow, or steal a clean piece of paper and a pencil. Not that greasy burger wrapper you just tossed in the work bench garbage can that your dog's eyeing up. He might just not be able to contain himself and you don't want to wait for his digestion unless you're by chance checking for worms anyway.

For the advanced- a pen. Not the Dunhill, gold nibbed, your grandfather gave you for graduation. Something that laquer cleaner can clean off the grease. Next, record those turns just in case an advance case of ADHD set it from all that carb cleaner fumes exciting those litlle grey cells into thinking Hendrix is an early form of rap music.. A smilely face with a hash mark for where it was works too. It perhaps will be some consolation if the darn thing still doesn't start and you've got to start over.:smile:

Now riddle me this- will a Zenith equipped E9 that's sat for 2 years start without without the choke flaps in a closed position? Or is there a reason that georgous german sled was sitting there that long cause someone monkeyed with those chokes and the owner'sex wife was just pissed about the girlfriend.

 

[m5bb]

Success today.
Removed the idle solenoids today. Inspected and cleaned and checked with 12v. Operating fine now.
Had to remove upper radiator hose to access solenoid on front carb.
Found split in vacuum line to distributor and also another small hose from the bottom of the carb to right below the gas inlet had pulled loose.
Air leaks kill idle.
While solenoids were out I sprayed carb cleaner through jet opening on top. Came out where solenoid mounts.
Not sure of location of idle screws on carbs? Saw a couple screws on valve cover side near bottom but do not look like conventional idle screws.
So past the readjustment of the screws.
Installed new points, condenser, rotor and cap.
Had new spark plug wires but have a question?
There is a lead from the high tension wire to the coil that goes around the wire to plug #1? Actually the #1 wire goes through this round rubber ring . How do you change this to the new spark plug wires?

Engine started well and was in warm up (High idle) and then went to a pretty normal idle. I adjusted the main screw that controls the shaft for both carbs so the idle speed was around 800 on the tach in the car.
Not sure about that accuracy but it sounded about right.
Some rolling of idle speed but not terrible.
Read about air cleaner affecting idle speed? I had it off and plugged the small vacuum line but valve cover breather was open.
Does this really mater?
Ran well but did not get to drive very far as it started raining.
Not taking this beautiful 3.0 out in the rain.

I have some carb sync gauges I use on my S38 motor with independent throttle bodies.
Will try that later and see if carbs can be synced a little better.

Help with the spark plug wires would be appreciated.

Thanks again guys. Made lots of progress but not perfect.
At least drivable.
Gary

 

[Stevehose]

The set screw for the main linkage should not be used for final idle, it's used to raise rpm up to set the timing (did you do this?), this screw is then backed all the way off the so it is not touching the linkage. The idle is set by the butterfly and mixture screws on each carb during the syncing process. They are located on the passenger side at the bottom of each carb, the butterfly screw is what stops the linkage for each carb. This may help:

http://www.e9coupe.com/forum/showthread.php?t=10942

Also check the section out here on syncing:

http://www.e9coupe.com/tech/zeniths/bmw1/bmw1.html

I don't use a CO meter, I just adjust the mixture screws for highest idle then follow with buterfly screw adjustment for final idle/syncing.

 

[m5bb]

Steve,
Thanks for the info. I think I misunderstood the info I read.
I thought you weren't supposed to change the butterfly screws on each carb. My bad. I thought those screws on the valve cover/passenger side at the base were the idle adjust screws.
I am working on this car in a storage facility. It's big but not next to all my tools and a cold drink. In the mid to high 80's here in metro Atlanta.
I can at least drive it the 15 miles or so to my house and garage.

Then I can do a more complete job on the carbs.
I did not do the timing yet.

Can you explain the attachment around the number one plug wire.
A sensor of some kind?
Can it be installed on a new set of wires?
Can the end at the distributor of the spark plug wire be removed or will it ruin the wire?

Have a few other jobs to perform when back at my house.
Front end is 3-4 inches higher than back.
Radiator needs flushing.
Interested in installing fan with more blades?
Saw links to this issues and will get to them with time.
Thanks,
Gary

 

[Stevehose]

Without seeing a picture I would guess it's the wire that goes to the Test Socket (the one with the orange cap on the drivers side between the fender and the power steering reservoir). This allows a mechanic to check timing by plugging in there and not disconnecting the plug wire to #1 cylinder back in the day. Or some variation of the theme.