Less than 1 volt going to injectors, thus no start

surfdogskier · 06:46 AM

Hey guys. I think I may have found my problem. My injectors are not shooting any gas. I took your advice Dave @ Pelicanparts about pulling out the injectors and placing them in a jar to see if they spray gas when turning over the engine. The 2 I am checking are on the driver side. Neither spray fuel when I crank the engine. Using a volt meter, I am getting less than 1 volt every half second or close to that when turning over the engine. The injector needed at least 3 to 4 volts to spray when I was clean out some other ones.

What would trigger low voltage to the injectors? What is the power source and could it be a ground issue? I read on some other sites regarding injectors, the injector is triggered by the gound wire pulse. The positive lead is always 12v.

Thanks in advance.

Dave at Pelican Parts · Dave at Pelican Parts's Garage

D-Jetronic is basically the first mass-market electronic fuel injection system. As such, it sometimes works differently than most systems today do. One of these differences is how the injectors are triggered; D-jet injectors have a full-time ground and the ECU will turn power on and off to open and close them. Almost all other systems (including L-jet!) supply power full time to the injectors, and the ECU will supply a ground to open them and remove the ground to close them.

I would first ask how you are measuring the voltage. Does the voltage match what you see on the "good" injectors? If so, then that very likely is not your problem. Many voltmeters will give you an "average" reading on a changing voltage, rather than trying to accurately show the voltage at every instant. (It makes things much more readable.) So there's a significant possibility that your reading is not completely accurate, which is why I suggest comparing it to the injectors that seem to be working.

If I read your other thread correctly, you say you are having trouble with the driver's side injectors? The injectors are worked in pairs diagonally across the engine. The same power signal goes to both injectors in the pair. The grounds are separate, though, and are paired differently. I don't remember which way they are paired, though. Double-triple-quadruple check the grounds for the suspect injectors; they will attach to a tab on one of the washers for the case through-bolts, usually on top of the motor by the flywheel end just in front of the rear engine tin.

If you were having trouble with the passenger's side only, I would suspect fuel contamination as those see the fuel first.

--DD

surfdogskier · 01:48 PM

Dave, once again, thank you for your input. What I would do to have you as my next door neighbor.....

The driver side injectors are what I took off just because they were easier to get too. Neither injector fired out any gas. I'm sure the passenger side is doing same thing but I will check. I ran some gas through the lines with the injectors off after I installed a new fuel filter to get any junk out of the lines. They should not be clogged. They are brand new injectors.

I will try and locate the ground for the injectors. There were so many loose wires and loose vacuum hoses, many going to the wrong places, on my car. I am trying to get them all sorted out.

Worse case senario, since my voltage directs the pulses as you said, could I just run a separate or new ground wire to each injector?

**** Follow Up since writing above post ****

It was hard to trace the grounds but I think I found where the were pinned directly under my air filter unit on the engine itself. My engine is very oily and dirty. I want to get it degreased up when I get here running. Would I be better off installing a new ground point and connecting it straight to the negative battery lead? That way I can remove most of the grounds I have and put them in a better and cleaner area.

Also, what are all the connectors for on the ignition coil? My coil is really shaky. The clamp is connected to the motor well but very loose around the ignition coil. If those are ground points on the coil, they are not getting a good contact at all.