1982 VW Rabbit with CIS Fuel Injection


#1

I have fuel to fuel block but not to injectors…why?


#2

@GeorgeSanJose‌

This is right up your alley, since you had one of those Rabbits, I believe . . .


#3

I remember the OUR GANG comedy series from years ago. I have to wonder if the OP realizes that screen name might not be proper.


#4

Our Gang, the Bowrey Boys, those were great shows.

Yosemite


#5

You have the K-Jetronic system (also called CIS). Google “troubleshooting K-Jectronic” for lots of info on it.


#6

I’m very familiar with these systems and the reason for no injector spray could be due to any one of a number of reasons. This is all assuming the fuel pressure is correct. CIS is very, very touchy about system pressures, warm and cold control pressures, etc.
A specialized tester is needed to check those pressures.

Stuck pressure regulator, stuck fuel distributor plunger, air leak or leaks, and stuck air sensor plate are some of the reasons.

VW CIS is prone to air leaks around the fuel injectors. Whether the seals and injector seats are bad enough to cause this problem with your particular car I do not know.


#7

@ok4450:
Speaking of these CIS systems, about 4 years back you were wrestling with a Saab that would not stay running. I remember you sharing everything you tried. More important, however, I remember the valuable exchange of diagnostic ideas on this forum that you engaged everyone in.

Were you ever able to resolve that problem?


#8

“I have to wonder if the OP realizes that screen name might not be proper.”

Say what? Buckwheat is also a plant and makes a great pancake. There is too much PC in the world for my liking. I might just drive my vehicle down to the store this morning and gets some buckwheat flour. I’ll probably stop and gets some gas as well.


#9

I had a late 70’s Rabbit and fixed the fuel injection system several times. I think it was the K-Jetronic, a totally mechanical fuel injection system. No electrical involvement with the injectors, other than the electric fuel pump. The amount of fuel injected was metered by a sort of wind vane that measured the airflow to the engine. As that vane moved upwards due to higher air flow, it would pull the fuel distributor plunger rod, which would allow more fuel to the injectors.

@ok4450 's advice is spot on. Among the things OK lists, from my experience an obstinate fuel plunger hanging up inside its bore is the most likely cause. It’s usually a result of sand or grit in the fuel tank getting past the filter and getting stuck in the fuel distributor. Often this happens when the fuel lines are opened up for some reason, like replacing the fuel filter. Soon thereafter the engine will balk, have little to no power. Sometimes even stall. You can usually tell this is the problem by removing the rubber thing covering the wind vane, and lifting it upward with some pliers or a big magnet. If you feel any uneven resistance, either going up or down, that means there is grit on the plunger.

The solution is to take the fuel distributor apart and clean all the surfaces, especially the plunger, so they are clean and shiny like new. The CIS system is very sensitive to contamination with grit, so this has to be done with att’n to not introducing any grit or contamination back into the system as part of the repair. Its easy to make the problem worse rather than better if this advice isn’t heeded. Create as clean of a work environment as practical in other words.

It’s a good idea when doing this to check the O-rings on the injectors and replace any that are distorted or broken. Those O-rings for me didn’t last very long before needing replacement, 2-3 years.

Further advice: There’s a John Muir (not the naturalist) book covering this era of water cooled Rabbits and for the DIY’er Rabbit fixer is pretty much mandatory.

One other tidbit of advice: When doing fuel system pressure testing and injector spray pattern testing, its very possible to get a lot of fuel in the cylinders without realizing it. If the car won’t start after you think everything is done and put back together, consider a major engine flooding problem as a possible cause. If so, remove the spark plugs and let the fuel evaporate. Depending on how much fuel is in there, it may take a day or two. Best of luck.


#10

@JoeMario. I never did resolve that problem and the car is still sitting in my drive. One of these days my temper will calm down and I’ll take another stab at it.

The frustrating part is that I’m familiar with the systems, have the specialized pressure gauge and CIS service tools along with the pressure charts and just found myself standing there thinking WTH.

It may sound convoluted but I know WHY it won’t run. The problem is that I can’t determine the reason for the WHY.
The WHY is that the air sensor plate is not lifting when the engine is cranking over which means the injectors will not spray. That usually means a sticking fuel plunger, sticking air sensor plate, incorrect chamber pressures in the fuel distributor, or a substantial air leak in the intake tract.

As an analogy, think of this as a float arm in a toilet tank. When the tank is full no water enters; when the water level drops the float arm moves and water enters the tank.

Everything is spot on with the pressures, plunger and sensor plate free as a bird, and not even the slightest sign of an air leak.

The slightest raising of the sensor plate with a magnet instantly starts the injectors to whining and spraying so one would think air leak in the intake tract but that’s not the case; verified both visually by disassembly of the tract and with repeated smoke tests.


#11

@ok4450 have you done a compression test? I once fought a Rabbit the same way. My engine cranking rhythm sounded normal but I had 2 cyls with burned valves, resulting in not enough cranking vacuum to lift the plate. Can you lift the plate and get the engine to run?


#12

Yes, compression is fine at 165 across the board and acceptable for 212k miles. No jumped timing chain, frequency valve buzzes, no air leaks anywhere in the engine compartment or in the dashboard. I even isolated the turbocharger and smoke tested it to weed out an internal leak there.

With the air sensor manually lifted I’ve got it to sputter but it’s impossible to sync the air sensor with the throttle plate by hand.

Car was running fine, shut it off, and 2 hours later it was a no-start. Hasn’t run since.

Not only frustrating as I do not like getting whipped on any problem but it’s also embarassing for a guy who understands these systems. Like an ostrich, I need to find a hole to stick my head in… :frowning:


#13

@ok4450‌


#14

That’s me everytime I look at that car… :slight_smile:

Honestly, at times I’ve even considered ripping the CIS off of it and adapting a normal, electrically pulsed injection system to it.

I would suspect the OP’s Rabbit problem is not as goofy as my SAAB problem. Considering the Rabbit injector O-ring problems and plastic injector seats an air leak is certainly possible.
The SAABs are not terribly prone to air leaks other than a cracked plastic valve cover vent or someone not fully inserting the oil dipstick back into the tube.


#15

@ok4450 … you are probably already aware of this, but the late 70/early 80 era Rabbit CIS had a fuel pump relay problem that was often intermittent. Typically the car would be running fine, then the engine would suddenly just stop running. Strand you on the side of freeway.

But no-starts could also be caused by that. The problem was usually that the relay plate contacts got burned, and you had to bypass those with some jumper wire. Also, the fuel pump relay has – as an input – the ignition points-closing signal. If it doesn’t get that signal, it won’t turn on. You might to figure out a way so the fuel pump runs all the time (as a debug experiment), see if that has any effect on your no-start problem.


#16

The OP says they have fuel pressure to the fuel block and which I assume they mean the fuel distributor.

An unknown here is what they mean by fuel pressure at the distributor and whether or not that pressure is anywhere near what it’s supposed to be. If it’s pressuring up as it should then the problem should not be related to the fuse block and pump relay.
If by fuel at the fuel distributor they mean it dribbles out then you may be right about the fuse block/pump relay problem.

I’m familiar with the fuse block/relay problems and did many work arounds with them. The fix was to bend the bottom tang of the pump relay out to where it protruded from underneath the relay housing. A jumper wire about a foot long with a female spade connector on each end was run from that tang to a 3-wire connector behind the fuse block which connected the fuel pump.
This bypassed the internal circuitry of the fuse block and the burned wire connectors on the back of the fuse block.
The other option was to replace the fuse block and repair the wiring and connnectors; a bit pricy.

Too much high current going through pins and wiring that was too small was the root cause of that problem… :frowning:


#17

Did you ever figure out what the problem was?
I have exactly the same problem.
Thanx