fuel injection will not fire no pulse?


Asked by GuruYSD47 Feb 17, 2020 at 02:36 AM about the 1986 Mercury Grand Marquis Colony Park Wagon RWD

Question type: Maintenance & Repair

Were is the FI injection pulse location located (how to check & fix).

7 Answers


The injector drivers are part of the main ECM, but you need to make sure you have crank signals getting to the ECM before condemning the unit. Wiring is a concern on a vehicle this old.

2 people found this helpful.

Hopefully you have the Ford OBD 1 system and not the Ford MCU, If you have the OBD 1 then you need to find a shop that still has the old Ford OBD 1 breakout box so they can do a pin by pin test. If it has the MCU you maybe stuck with dealer due to the specialized equipment for the MCU system. Now what I would do is replace the crankshaft sensor as those are a known high fail item. Then if that didn’t get it back running then Hang on to your wallet cause it’s going to get expensive.

1 people found this helpful.

Did check the computer, yellow wire sending 12V blue wire receiving 12V that seams to be good?


There’s much more than that to check the computer, you have reference voltage, computer grounds, sensor grounds, etc. Way too much stuff to test for a novice without the correct equipment.

1 people found this helpful.

Hi again, hope that you don't mind me you are the most knowledgeable person on these issues. The no.4 on the EEC. green/yel. (pulse/ignition} goes to the - side of the coil. I have 2 green wires on my coil connector.the second wire could to a tach .or ? It has a powerful pulse from it. could I attach this wire somewhere for my Fuel Injectors? will not work by adding to 12V. Thanks for your time on this. Justin


That won’t work, the reason is injectors are negativity triggered from the processor, and the pulse width of each injector is also determined by the same unit. Don’t go running wiring around as you could cause expensive components to burn out and in your case possibly components that are no longer made. Try a new crank sensor first.

1 people found this helpful.

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