Hi Everyone,
I have a 1986 420 SEL. From reading lots of threads on the forum I find that there are several Jetronic fuel injection systems depending upon year, model etc. Can anyone tell me which on mine is?? Also what is CIS??

Thanks

Your system should be a KE-Jetronic system. If you are planning to work on or adjust this system you need to purchase a copy of "Gasoline Fuel-Injection System KE-Jetronic" by BOSCH. You can find it on amazon. After reading the publication (about 40 pages) you will be able to understand what all the post are talking about.
CIS stands for contenious injection system.

MAGV5

Correct, he has the CIS-E system first seen on the W126 in 1986.

CIS stands for continious injection system. There's always a "fog" of fuel waiting for the intake valve to open.

__________________
1993 400E


Mercedes Benz technician since 1982

ASE Master technician to 12/2015

Thanks magv5 and clarkz, much appreciated.
I have been reading many threads and found out quite a bit about the systems, but as a novice I could not readily identify the differences among the several systems out there. Thought it better to verify with those who have experience as I certainly have none with MB's.

I do have some experience with engines and cars. I have worked on my old 57 Chevy and my 69 Mopar and others for many years but they do not have fuel injection and all of the electrical switches, valves, sensors, etc.

The 1986 420 SEL has a starting problem. It has been 8 or 9 months since I have started it, I keep it as a spare car.
Tried to start it the other day and it would crank but not start. I shot starting fluid down the intake and it immediately started but for only a few seconds. I repeated the same thing 3 or 4 times with same result.

Since it tried to start but would not continue running I am feeling fairly confident that it is a fuel issue and probably NOT and electrical problem. ??
BTW I did hear the fuel pump(s) running, don't know if both were.

About the car---
I've owned it for about 15 years and hardly know anything about it.
It has had no work done on it in probably over 5 years or more and driven very little. I have always changed my own oil, filters and a belt or two but nothing has ever actually gone wrong on the car. I suspect that lack of use is the biggest problem.
The fuel filter hasn't been changed in probably over 5 yrs. The only thing that has been replaced is a distributor cap, plugs and wires

I realize that it could be 100 other things from perusing the forums. My logic tells me that the fuel filter among other things could be plugged and that is my reason for starting with the fuel. If I get fuel up to the engine and still no start I would think that that would eliminate at least one of the obstacles. I think that if I took a gas line off somewhere on the engine, turned on the fuel pumps, and I get no gas out of that line then I would definitely have to start in the back for pumps ,filters etc.

If I tried to do a fuel check to see if fuel is getting from the tank to the engine, what would be the best ( thing-line-part) to loosen or take off to see if the fuel is getting that far??

I'm just trying to find out what line I can disconnect on the engine to test it. Would one of the lines coming from the tank go directly into the fuel distributor? If so would it be to the upper half or lower half of the distributor. Also could I check the fuel pressure while I have a gas line off.
(Just bought a pressure gauge up to 100psi) but I don't know where to check it from.

I will be very thankful to those who have time to respond. Dale