4000cs quattro from the ground up
 

I recently bought an '86 4000cs (5 cylinder, fuel injected, manual transmission, quattro) as a project car and I'm looking for some help with trouble shooting. Here's the story: The previous owner said that the car ran fine until suddenly it would not start. He pushed it into his garage and didn't touch it for 10 years. I just bought this little gem and after replacing the battery I confirmed that the engine will crank but will not start. I also confirmed that the fuel pump was bad (maybe the reason for the original no start 10 years ago???). After draining the fuel tank, replacing the fuel pump and adding fresh fuel, the car still will not start. Upon further inspection, the engine is getting spark and I see that all of the rubber vacuum lines are complely deteriorated. I plan to replace all of the critical vacuum lines, fuel filter and spark plugs over the next few weeks. I'm looking for some direction on other causes of a no start from those of you that have owned these cars. Any help you can offer would be much appreciated.

So i was wondering if you got her running yet?

Well, I tried to get her running but failed. I replaced all of the vacuum lines, confirmed that the fuel pump was working and replaced the spark plugs. The car just cranked and cranked but no start. I sprayed starting fluid into the intake and could get it to run for about 2 seconds. I did notice one very strange thing. As I cranked the engine over, I could hear the cylinders build compression for about 5 seconds then suddenly there was no audible cylinder compression. It sounded like the crank and cam were just spinning for another 5 seconds. Once it started with the starting fluid, exhaust gas came out of the intake boot between the intake manifold and fuel distributor and the engine stalled. My only thought is that the timing belt may have slipped at some point and the crank and cam are now out of sync. Any other thoughts here?

I had one of those cars many years ago. Turn the crank to TDC for #1 & see if the timing mark on the belt cover line up with the mark on the cam pulley. You may have to give the crank two turns. It has been a long time and I don't remember all details, but you should be able to find a Haynes repair manunal with all the details. That engine uses constant flow injection and you may want to look at flapper valve under the air cleaner. Press down on the valve and open the throttle with the ignition ON (engine oFF)and the injectors should be spraying.

Cis
 

That's a classic CIS fuel injection problem. I just got done working on a Porsche 1979 928 with this system. The piston that regulates the fuel flow is stuck and the fuel distributor is all varnished up. Unless you have some skills this needs to go to someone who has the tools and knowledge. Keep up dating this post, "I know a guy" (famous last words) but I really do. Give me a couple of days I'll get back to you.

Love the 4000 quattro!

I've had a few rabbits with this same system, that I bought not running and had fuel problems like this. It sounds like it back fired through the intake system, so like another said, you'll want to take that large rubber boot off and see if the approx 5 inch round disc inside the airflow housing is bent or sticking. That round disc is bolted to an arm underneath but on top of the filter, and that disc and arm needs to be able to move freely from rest clear to the top which if the engine was running would be full throttle high air flow mode.

Check cam and crank timing too, make sure the cam belt didn't break. Ignition rotor should be pointing to the #1 cylinder spark plug wire, cylinder #1 cam lobes facing upward, and piston at tdc for #1 cylinder also. That should hopefully all line up for you, if the cam is off 180 degrees than turn the crank over 360 degrees and check for the timing marks to line up as described.

It's possible that fuel isn't getting to the fuel injectors because the fuel distributor head is gummed up. I'd do a compression test before doing anything else. If that fuel head is gummed up the plunger won't move very freely inside the fuel head either. You'd notice this when you try to raise and lower that round disc and arm assembly.

If you want to test the spray pattern of the injectors you'd need to do a couple things. It helps if there is fresh fuel, a good fuel filter in place, not the old one, and take the fuel injectors out of the head. Put each one inside a container so when they spray fuel you contain the fuel instead of having it spray everywhere and becoming a fire hazard. Then have that large rubber boot off the air flow meter (so you can raise and lower the control arm inside the air flow meter) bypass the fuel pump so the pump runs all the time, and then you raise the control arm and see how much if any fuel you get coming out of the injectors. Inspect the spray pattern too. Even if you get it running but have a bad spray pattern the car won't run well. Injectors can be cleaned too, by a shop.

I know you've heard this before, but with timing, compression, spark and fuel the engine should run. But check for any major vacuum leaks too, that doesn't help and it's not uncommon to have a large split in the rubber boot on the bottom side, that goes from air flow meter to throttle body.

Thank you for all of the detailed assistance with this. I've done a few of the things mentioned but I'll check the cam timing and cylinder compression first.

I have removed and inspected the large intake boot. There was a tear in the boot that I was able to repair. While I had the boot off I was able to clean and inspect the airflow disc on the top of the air filter housing. The disc is in good condition and does move freely however it only moves up and down in a range of about 5 mm at the most. Is this a normal amount of movement or should it have more movement???

That cone/disc should come up enough to put about 3 fingers between the funnel and the round disc, at the tallest point, so 5mm is not enough by a long shot. On this diagram you can see how the plunger (no item # listed) is raised straight up and down by the arm that is kind of L shaped that has that round disc on the end where the "11" is located in the drawing. What happens is the fuel head, black casting with the 5 fuel lines coming out of it, also 13 on the diagram, has a polished plunger in the center that in the diagram is making contact with the L shaped arm at the bottom of the plunger. It's probably gummed up in the fuel head and that's why it won't raise any farther than 5mm. Unless you have a mechanical problem in the arm or hinge that won't let it go up any farther. I would remove the fuel head inspect that plunger and the the port that it goes up and down in. Be careful, when you raise the fuel head off the airflow housing that plunger can drop out of the head. It's precision machined and you don't want any gouging on the surface of the plunger from that hitting the driveway.

Those fuel heads are or were offered as a reman part, so they can be rebuilt but there are no kits for you or I to do that job. From what I've heard they aren't the kind of thing that is usually torn apart, cleaned, and put back on. But, if you can't get a reman, or if you can and it's 700.00, but your car isn't worth that kind of investment, then you won't lose by tearing that fuel head apart. Just remember if you do buy a reman those fuel heads need to be completely assembled to be eligible as a core, or you don't get that core money back. That's true for starters and all other core items. Audi or other parts stores won't take a core when it's in pieces in a box.

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Sorry it took so long to get back. You can have your system rebuilt, contact Zims Autotechnik @ 1-800-356-2964. They handled the CIS parts for our 1979 Porsche 928. Torn boot will cause a problem.
Got to go rescue my wife. Her A6 just threw a belt.