Hi I have a 1986 ranger with the 2.9l fuel ingection I’m have an issue with that I can not seam to figure out.
I have weak spark at my coil won’t make it to the plugs I have put in new. Cap rotor distributor pick up ignition x2 control module x2 coil x3 changed wire harness …… I can not figure it out changed the ecm out as well any help would be very appreciated


thanks in advance

 

How about the spark plugs and spark plug wires?

 

The plugs and wires are new to yes but I’m not getting a strong enough spark for coil to cap every now and then it will spark on a plug but not often

 

Ignition coils generate spark voltage when the 12volts is cut, in the case of most vehicles the Ground is cut, and that cuts the 12volts, because there is no 12volts without 0volts(a ground)

So in the old days the Points inside the distributor was the Ground for Coil's "-" terminal, and the "+" terminal got 12volts with key on
As the points opened(ground was cut) spark was released, when points closed coil powered up again to build new spark voltage, simple

Electronic ignitions replaced the points(which wore out) with a "sensor", the sensor told a transistor when to unground and ground "-" terminal on the coil, even simpler

Weak spark from a coil can be less than 12volts at coils "+" terminal
"-" terminal ground is not being cut off fully
High resistance in coils Primary side

You can check coils resistance(OHMs) with an OHM meter on the "+" and "-" terminals, under 1 OHM is expected, 0.6 to 0.9 OHMs, on single Coils, Coil Packs spec is under 1.7 OHMs(just FYI)

And you can check the voltage at the coil with key on, test "+" terminal to "-" terminal AND then test "+" terminal to any Ground, like engine metal, should see exactly the same voltage
If its 12v from "+" to engine ground, but only 6volts, say, between "+" and "-" then the spark module is not grounding the coil fully so weak spark

You can test a coil out of the vehicle as well, just need two jumper wires and a spark plug or spark tester
Hook up coils "+" to 12volt battery terminal
Touch the coil "-" to 12v battery negative(ground), then untouch it and you will get a nice strong spark if coil is working well
Repeat as much and as FAST as you can and you should get a nice strong spark each time you remove the ground at the coil

 

I have 9 volts at my (-) at coil while cranking what would cause that

thanks agen

 

No, 9volts is fine, for spark, when starter motor is active, although it does indicate the battery may be getting old

Expected 12v battery voltage when cranking is about 10volts, maybe 9.5volts when battery is older, under that and its either really COLD out, i.e. 32degF or just a 5/6 year old battery

But in any case 9volts is plenty to get a good "hot" spark from any ignition coil

Generally speaking an ignition coil amplifies voltage by 1,500
12volts X 1,500 = 18,000volts
9 volts X 1,500 = 13,500volts

Most spark plugs like to have 12,000 to 25,000volts