I’ll chime in again on my late 70’s Rabbit experience. Hopefully might be of some help to the OP. My Rabbit had the Jetronic CIS, but forget which letter. It was a non-electronic fuel injection, the totally mechanical version, including the injectors, used a big round disc-like vane centered in a sort of wide venturi tube to measure the airflow. More airflow would cause the vane to rise , which would allow the metering rod in the fuel distributor to rise and pass more fuel to the injectors.
This vehicle never exhibited the OP’s symptom. The engine either ran like a top from the first cold start of the day to the final key to “off” at the end of the day; or – this was infrequent – it ran like total crud. In the latter case, it would usually idle fine, but as soon as you shifted into second gear and tried to accelerate the engine would just stop producing power. You could only go about 35 mph max with the pedal floored. That’s that situation when cleaning the fuel distributor would fix it up straight away. Inspection showed the fuel metering rod was binding due to grit.
I did experience some other problems. The fuel pump relay and associated wiring being damaged by heat caused the car to stop running and strand me on the side of the freeway once in a while. The symptom was it was running fine, then 5 seconds later it wasn’t running at all. And I had a problem with the ignition system in wet weather for a while, which would cause the engine to stop if I ran over a puddle of water. It would start again, but I’d have to wait 15 minutes. This turned out to be a tiny almost invisible crack on the underside of the coil.
So what should OP do? As db4690 says, probably the first thing is to bring all routine maintenance up to date. If this happened on the Rabbit, I’d be inclined to install a new air filter, fuel filter, new spark plugs, points/condenser, distributor cap/rotor, spark plug wires, and remove and bench-check the coil with a magnifying glass for tiny cracks. While doing this I’d inspect the aux air valve for any signs of contamination or binding, and clean the fuel distributor (again, sigh). If that all didn’t fix it, I’d install a fuel pressure gauge and see what it registers when the symptom is occurring. Still a no go? Then I’d remove all the injectors and check their spray pattern.
@db4690, I actually liked working with most of the CIS issues as they were easy to do and pretty profitable. It’s the smaller percentage of odd problems that would drive a guy up the wall and curse the guys who designed it.
CIS injectors are definitely prone to poor spray patterns and leaking off while the engine is at rest.
I’d wager that if someone went to a Pull A Part yard and yanked a 100 used injectors out of various types of CIS cars it would be a miracle if more than a couple tested fine.
According to the VW factory rep, CIS injection NEVER, EVER screws up.
The most common problems were a somewhat rough idle due to air leaks at the injector seals or poor spray patterns followed by balky starts due to pressure bleed-offs or problems with the cursed Control Pressure Regulator.
Some of the oddities included the fuse blocks burning due to fuel pump current draw and the vapor control system screwing up which would then lead to engine vacuum sucking the gas tank flat.
At the pick a part near me, all the Benzes in the yard have no fuel distributors
Those seem to be among the first parts to go
I’ve seen mechanics from the small independent shops there, scouring the yard for parts. Many of them are wearing the company uniform, so you know who they work for
I suppose it might make sense to fix an older european car on the cheap . . . provided you’re absolutely sure those bone yard parts are working correctly
I remember a car that was running quite poorly due a vacuum leak. It was located under the fuel distributor. And this was well before any smoke machines were around. We used several cans of carb cleaner to find the exact leak. It was also very subjective. Sometimes when you sprayed carb cleaner near a suspected leak, one guy swore the engine was idling better, while the other guy swore that nothing had changed
I can understand why they went after the fuel distributors. The last time I priced one of those things through Advance Auto it was about 2400 dollars for a reman.
Wonder what the shops hit customers up for a used one…
The Pull A Part yard here gets 35 bucks for one and the last time I was there most of the Benzes still had their fuel distributors in place. Most of the Benzes they have are the 190 series Baby Benzes or whatever they’re called.
find and replace the overvoltage protection relay. Most of the time they are under the hood in back of the battery. It is a tall silver relay with a plastic transparent door on top with a fuse built into the top of it. The transparent door hinges open and closed. I suppose it the fuse is blown you can try replacing it but I always found that replacing the entire relay was best in the long run.
the reason i suggested to replace the overvoltage protection relay is It could be that no voltage is being sent to your engine control unit. When there is no voltage being sent to the ecm you have no engine management and the vehicle just runs on vacum pulling on the cis plate only. The ignition system stands alone on this model and that why it continues to run.