CIS Question...81 SC
 

There's a fuel rail that comes from the fuel distributor to the Wuhr. I think it doesn't seat well at the Wuhr end. It appears to be a pressed unit. Is there any way to rebuild this thing with fuel line and a new fitting, or should I just bust leather and buy a new rail?

do you mean the half rubber half steel line that is attached to the middle top of the fuel dist? if so, i wouldnt worry about it unless its leaking

That's the one. I'm trying to figure out why I have a warmup issue. So I pulled both Wuhr hoses off to give them the old mouth-suction test. Both held up fine, and I'm learning to love the taste of gas. But when I put it back on, it was leaking a little. So I put the 14mm wrench on it and really had to crank it down hard to stop the gas flow. That's a tapered fitting, and it seems it shouldn't require that much force to seat it. At least that's where my brain cells were focussing!

if it was leaking between the hose and the fitting then you would have a problem.
try putting a new fitting on ur WUR to solve that.
whats the warmup issue?

The problem with warm up is it chokes and stumbles and even dies at start up. After a second or third try it runs very rough and after a minute or so finally settles in and runs perfect. It's only at startup when cold. The weak and leak was where the line attaches to the WUR, I don't understand putting a new fitting on the WUR. The entire rail seems to be a pressed together unit. No??

to sort out this issue youll need to make the WUR adjustable, then adjust it.
it sounds like its too lean on start up, thats what usually happens. over the years the engine develops leaks in the intake tract, unmetered air, so the stock setting ends up being too lean. on the WUR there is a fitting- male/male- that the hose in question screws into. since you cant replace the hose end you might try a new fitting to cure that leak. if ur interested in setting your car up right do some searching and reading here and u should be squared away. you should have a set of fuel pressure gauges at a minumum

OK, that males a little more sense. Thanx Jason.

Poor starting
 

It could also be a problem with the cold start valve. Check to see if its getting 12v at startup and if it is spraying properly. The cold start valve should only be open for a few seconds but is pretty important to starting a CIS engine.

not very good advice from above.
stop sucking on things. that proves nothing.

first you dont just go and make the WUR adjustable and start adjusting it. you have to know what the fuel pressures are before you adjust it. before you do that you need to make sure the ignition works as it should. plugs, rotor, cap and good wires. set timing and check advance. then you need to make sure you dont have air leaks. back to the WUR. it may be that the screen on the input to the WUR is dirty and raising the fuel pressure. if the heating element or the spring in the WUR is bad making it adjustable will not help. larry at flowcontrol can rebuild them. it would not hurt to send the injectors and have them tested and cleaned.
once all that is done have the mixture set.

the CSV.
if the car starts the CSV is working. the CSV has nothing to do with it running bad once started unless it stays on.

first thing i would do is check pressures cold and warm. that can tell you where you need to go from there.
make sure the ends of the fuel line and the fitting on the WUR are clean and that the line is going on straight.

My thought was air leak, hence the sucking test. It's not the WUR. I've had a used one on, a rebuilt one on, and a brand new 'In the box' one on, and the problem didn't change. Ignition system has been gone thru, timing is correct, and a new vacuum module installed. I was reading the service manual, so apparently the cold start module is fine or the car wouldn't start. It gets frustrating because I know it's something relatively simple. I just want this motor to work right before I try and sell the car. I've located a reputable mechanic/shop down in Sacramento, so I might just take it to him.

Two things are very important when trying to fix a problem over the internet.

1) Input/feedback from the person with a problem
2) A systematic plan for testing and eliminating possible causes.

Your post, above, helps tremendously because it gives us background and information that can eliminate some ares of concern, such as ignition and timing. However, I would suggest you not abandon the systematic testing approach.

You suspect an air leak and you have eliminated the WUR without actually testing to see if the WUR is functioning properly or the fuel pressures are correct. Just because you have changed out the WUR several times does not mean the fuel pressures are within spec. You cannot eliminate the WUR as a suspect until it has been tested.

If you choose to pursue air leaks, go ahead, that's your choice in a diagnostic process, just follow that testing procedure to completion, then, test the fuel pressures. If the problem is solved by repairing air leaks, still test the fuel pressures if for no other reason than to see if they are in spec and get a base line for further issues.

My point, follow a systematic plan of testing and elimination. Do not assume anything. Get yourself the proper equipment, a fuel gauge set, and use it. You will need it in the future if you have a CIS system. Keep the feedback coming and report everything you do as no one can know what's been done without your information.

Fair enough. Down and dirty.

Step 1.

Plug the hose with a nail that goes into the distributor vacuum unit. The one that is closest to the center of the distributor (idle timing retard function). Just the hose, not the metal port. Start car cold and see if it makes a difference. Bet it does.

Step 2.

I have been using brake cleaner in a spray can lately to hunt for them(vacuum leaks).

Put the spray stick on the can and start the engine. Spray lightly at the base of the intake runners where they meet the heads. Where the runners meet the rubber gaskets at the airbox. Around the airbox, including behind, where all the tubes and hoses plug in. Where the injectors go into the intake runners.

RPM's will change when you hit a leak. Fix the leak.

I have been doing this (with starting fluid and carb cleaner) for years without issue but don't douse the distributor while running if you know what I am saying. Brake cleaner is not as volatile.

Nice thing is there is so much information in this forum that if you latch onto a good thread (or three) this becomes very do-able for a regular DIY guy.

This is good feedback and I appreciate it. I'll go down to the barn in an hour or so (when it warms up) and do a little testing. I don't want to buy a lot of tools because, as stated, I'm not going to keep the car. As mentioned in my other thread, I might just sell this car and my Z28 and get a 993 or 996. Old dude's Porsche with creature comforts and cold AC.

Humor me and try the retard hose nail plug trick first. If you have factory hoses it will be the blue one.

If you can't figure out which one it's the hose with suction at idle. Vacuum advance has no suction at idle.

What you do is give yourself a 5-7 degree advance bonus by killing the emissions related retard function at idle.

What's your goal?
 

Westy,

Do you want to know and learn how to fix your CIS problem/s? Or you rather have it done by a shop and pay him and be done with it? The problem you'll be having is finding not only a reputable mechanic but someone who understands how CIS works. So you have to make that decision.

I have not seen or encountered a CIS problem that a typical DIY'er like you or me could not diagnose correctly using conventional methods at home. It takes time and practice to be good in anything we do. Some people takes more time to be proficient others just learn it easily.

If you decide to do it yourself, this is the right place to begin. There are many guys in this forum that could help you and get your problem/s go away. Keep us posted.

Tony

Thnax Bob, I'll do that. It's an orange hose on my car. Same setup as on my Camaro, so that's an easy check.

Actually, your cars starting problem can be a cold pressure issue, it can be a cold start valve (CSV) issue, it can be a fuel pressure leakdown issue, it can be due to air leaks, etc. While I don't agree with sucking on fuel lines, just about everything else above falls into the category of reasonable advice. Even if you check something and it does not turn out to be a problem, at least you know that part of the system is working properly. There are lots of folks on this board with years of experience w/CIS. I have owned my 1980 SC for almost 20 years and have done all of the repairs and maintenance myself. Once you learn the ins and outs of CIS it is not a difficult system to maintain. Good luck with your quest!

Fred, you're only a few thousand miles away. Come on out and we can work on it together. I'll serve you up some great burritos and cold beer.

Fred you and Westy could agree to meet halfway...Austin TX would be great. Then we could all three work on our CIS setups together...we have better burritos and beer than CA

Do the basic tests.......
 

Westy,

Read and re-read again LJ's post. He explains the messages clear and simple than anyone I've seen in this forum. Others have a different approach to tackle the problem. Before you go and start doing some suggested procedures to identify the culprit, I strongly suggest that you fix the fuel leak first.

Get familiarize with the CIS set-up of your engine. Get a good reference maintenance manual like Bentley and the like. Read posts pertaining to CIS woes and problems. They become boring to read once you understand the basic principles about CIS. Tim Irwin has a nice thread about CIS troubleshooting for Dummies.

If you don't have a set of fuel pressure gauge to use for your troubleshooting task, you are wasting your valuable time. If you could get the engine to start from cold, you are ahead of the game. If you can not, that a different story. Keep us posted.

Tony

Distributor vacuum test - Negative change
Brake cleaner test - no change. Checked to see if it was volatile enuff by spraying in the intake and yup, RPM increased. I sprayed everywhere. This doesn't surprise me, as a few years ago I dropped the motor and replaced a few runner boots and injector O-rings and other little stuff. This problem is lasting for shorter periods of time. Today it lasted about 5 seconds and then idled fine. I dunno. As was suggested, it might be fuel pressures. I know my mechanic pretty much only works on older cars, a lot of them CIS. He said it was the WUR (AGAIN!!!) but I have no idea how he determined this. Haven't been up there in a few years. The car warms up quickly, so I have to let it completely cool down once I've done a test. The vacuum line slid right off. I need to trace it back to the other end. It's old hose, maybe it's cracked at the other end,,,although the brake cleaner test didn't indicate this.

Why can I not find Tim's article? Am I challenged??

CIS troubleshooting for Dummies.......
 

Westy,

Go to SEARCH, select Advanced Search, and type Tirwin. Select 'started by....'. You'll find all the threads started by Tim Irwin. Keep us posted.

Tony

Also I want to repeat....I'm not keeping the car, sad as that is. BUT, I'm not going to try and cover up an issue so some happy buyer turns his bank account into a black hole. If it's bad fuel pressure but only at startup, then I think we'd be getting into areas where I would be better off keeping my hands off of it. This car has appreciated significantly since I bought it. If it's gonna cost me a few hundred to fix, then so be it. I have the Bentley manual, so I'll go do some reading. I have an appointment with IPB Autosport in Sacramento on the 15th. If I can figure it out B4 then, I can cancel. Right now I'm gonna go read up on how to test the cold start gizmo!

let me repeat it.
if the car starts, as his does then dies, it is NOT the CSV.
with a bad CSV the engine will crank and crank and crank. lifting the sensor plate will make it start. (good test for the CSV circuit).
telling someone to make their WUR adjustable is NOT checking pressures.

i dont suggest brake cleaner. brake clean csn mess up rubber a lot more than carb cleaner can. spray a rubbber O ring and watch it swell.

if you feel pretty confident you do not have an air leak then its time to check pressures. you just cant do anything else at this point.
i could tell you things to do to determine for sure if you are lean but none will tell you why.
its the process of elimination thru testing instead of buying parts.


assuming everything is good after each test i would:
check air leaks
check pressures
check dwell on frequency valve
check mixture setting
check injectors
check air leaks.

check the intake bolts again. they came come lose.
check the rubber "turtle" that goes from the AFM to the throttle body. look for cracks.
if your oil tank is vented to the "turtle" or any other hoses go to the turtle, check them.
check the oil tank cap. it should have a gasket in the cap.
you have a lot of vacuum plumbing behind the intake that can leak. its a pain but it needs to be checked.

unless you have gauges about all you can do is look for air leaks.


otherwise sell it as it is.
i would buy a car that has bad cold running/ but i would expect to spemd $$ on a WUR, perhaps the time to take the engine out and reseal everything on the intake. but to me thats not that big a deal and i would rather start with everything working so that if i did have problems down the road my list of ssupected problems would be shorter.

OK. Everything you say makes sense. I'll piddle around with it' I know I'm not dropping the motor again. Did that years ago when the back was in better shape, and it wasn't easy then. I'll get my wrenches out and tighten stuff down, check some more vacuum lines. I DID remove the oil cap and there was little if any change in RPM. The motor was warm, and didn't care if it was on or off. I'll check the seal.

Stick with your gut, I had trouble with my 81 SC. Got a rebuilt wur, retuned and it still wasn't 100% there. My fuel line seemed fine but I replaced it anyway and now the car runs a lot better. Maybe gunk builds in the line or the fitting?

Thanx T I found it. And thanx for showing me how dumb I really am. Right now I just have visions of a 993 or 996 floating around in my head!!

Good example of unmetered air.........
 

Westy,

You just demonstrated in your last post that you have unmetered air in the system. The question is where is this coming from? A simple way to locate it is by pressure testing the system with a continuous supply of low pressure air (5 psi or less). Spray soapy water on suspected areas and the leak would show up (if any). With the engine in place, it is almost impossible to have a good and reliable test specially if the leak is underneath or behind the air box. Not until you have tested and confirmed that the air box is leak-free, the air box is a subject of interest.

Tony

Helping out
 

Wish I was closer, would be glad to help! The burritos and beer sounds good!

OK. The car is at the mechanics getting smogged. I'll let him do the oil and filter, too. I explained the problem to him. Told him to check and see if he can figure it out. If it's fixed, I'll figure my price and post it for sale. If not, then I'll drop 1k off the price. That should more than cover it. FYI, when I dropped the motor, it was to replace a cracked airbox and pop off valve. No more motor drops for this oldin'!!