75 450 SL Fuel Injector Problem

[Morrowdr]

I have 3 injectors not firing on my 1975 450SL. I have removed and cleaned all the injectors. I have moved the 3 that were not firing to a different location and they work fine. I have checked the fuel injector contact points and they appear to be working with continuity. I have checked all the wires and reset all ground connections. If the contact points were bad I would think the injectors would fail to fire in pairs. Any ideas what would cause just 3 to fail to operate.

Any help would be greatly appreciated.

Dave

[230/8]

I believe your car is the last year for D-Jet electronic injection. If so, there are trigger points in the base of the distributor that may be dirty. Fairly simple job to pull the distributor, remove the trigger points and clean them of any oily film. Replace the O ring seal on the base of the distributor while you are at it.. cleaning may solve your problem if you do not find a wiring issue.

230/8

[GaryF]

Originally Posted by Morrowdr

I have 3 injectors not firing on my 1975 450SL. I have removed and cleaned all the injectors. I have moved the 3 that were not firing to a different location and they work fine. I have checked the fuel injector contact points and they appear to be working with continuity. I have checked all the wires and reset all ground connections. If the contact points were bad I would think the injectors would fail to fire in pairs. Any ideas what would cause just 3 to fail to operate.

Any help would be greatly appreciated.

Dave

Hi Dave,

You are right, the injectors are paired in the following way:
1 & 5, 4 & 8 and 2 & 7.
Are you sure its not 2 or 4 injectors failing to work ?
- Each injector has two electrical pins, check that one pin for each plug is properly grounded.
- Check that the other pin is connected to its pair.
- What state is your wiring harness in ?
- Are you spraying the injectors out of the head to know for sure which ones arent working ?