I saw this question and answer on The BrickBoard, and having some experience with the triggering points myself, I realized that this is a valuable piece of work. Thanks to Jarrod Stenberg and Jack Austin for permission to reprint, and to Justin Little for asking the question. -Glenn.
October, 1997
Help,
I have a 1970 1800E with a fuel-injected B20E motor. Yesterday morning I tried to start it to drive to work and it was missing badly. By shorting out the plugs, I determined that all the plugs were firing, but when I disconnected the wires to the injectors, I discovered that only cylinders 2 and 4 were getting any fuel. I know the cylinders are paired in that manner, but why were two not getting any fuel? I looked at my shop manual and found they are wired as pairs to the control unit, so I thought I'd look for a loose wire or something. After looking at the mass of wires, I decided to ride my bike to work and come back to it later. Needless to say I was quite late.
When I returned from work and looked at it again, it started right up with all four cylinders. Strange? Also, that morning I was working the throttle under the hood as I was determining which cylinders were doing what. Anyway, when the engine was not running, when I opened the throttle, I could hear a ratcheting noise. I determined it was coming from the 1 and 3 cylinders because I could feel the vibration in the fuel injectors. These were the two not getting fuel. The sound did go away that morning, before I got the car started.
Nothing like this has ever happened, so I am a little confused. I checked the ignition system as described in both Haynes and Kenneth Ball manuals, and everything seems to be in order except this fuel problem. Any ideas?
-Justin
Justin...
You certainly are an observant soul. Not many folks would have noticed the injectors being actuated in pairs as the throttle was moved. Anyway the injectors on D-Jetronic systems are triggered by a set of points mounted in a slide-out tray in the lower section of the ignition distributor. These points don't carry much current, so they don't usually "burn," but they are quite sensitive to contamination.
The chances are that oil from the engine crankcase is finding its way up the distributor shaft and into the little room in which these points live. The oiling most likely will be due to a dead oil seal around the distributor shaft or a very worn shaft/bushing surface. Less likely is crankcase pressure building up and forcing the oil up the shaft. If this were the case, the crankcase breather would be stopped up and oil would be seeping (LEAKING) from the front and rear main seals, the valve cover gasket and the seal around the oil filler cap.
The fix is to remove the distributor and clean the trigger points. But first take the distributor cap off and rotate the engine until the rotor is pointing to the contact for #1 cylinder. Take care that the engine doesn't rotate from this position. Look at the trigger points carefully and if they are saturated with fresh oil or more stiff stuff, use mineral spirits to wash everything down first followed by an alcohol bath (ABSOLUTE, please, if you don't mind :-) to clean off the mineral spirits. Avoid the temptation to use carburetor cleaner. It will destroy other bits also being washed.
Don't use an abrasive on the points to clean "file" them, but do drag a bit of typing paper through them for a final cleaning. Clean out the little room in the distributor using roughly the same materials and approach. At this point I will assume that the ignition point set is serviceable, needs no adjustment and is clean. Stuff the distributor back in, making sure that the rotor is pointing in the same direction as it was before you removed the unit, use a timing light to properly set the ignition timing and have at it.
If your symptoms remain, either the trigger points are indeed bad or there are other problems lurking about. I won't bore you with all of the other possibilities just yet. Try the above and if the lump runs well for a while (50 to 300 miles) and then starts the same old thing over again, pull the trigger points once more. If the little room is all oily again go to your parts/service guru and see what you can buy or have repaired. Some guys will reseal the distributor and install new trigger points. Others want to sell you the whole thing. Good luck...
-Jack Austin.