I'm resurrecting an '86 GT which has sat for at least six years. New plugs, plug wires, known good distributor and coil. I've replaced the fuel pump which was dead. The system holds 40 lbs of pressure for quite awhile after the fuel pump has been primed, so I believe the injectors are not leaking. I haven't tested the compression with a gauge, but cranking it over by hand there appears to be good pressure on each cylinder.

However, the engine sounds like it's running on three or four cylinders. I suspect some of the injectors aren't opening, so I'll try tapping them and see if that makes any difference. If that doesn't help I'll take off the top intake plenum to access the injectors, but my question right now is... When the injector harness is disconnected from the main harness and a continuity test is done between "A"-"B" connectors and also between "C"-"D" connectors (basically the positive and negative of each injector bank), what should the reading be? I suspect the injectors must be connected in parallel because I get a reading of 5.7 ohms on each bank. Is this reading what is to be expected?

I have a set of used injectors here and each individual injector has a reading of 12.6 ohms. I'm just kind of surprised to be getting a reading of 5.7 ohms when testing a bank of them together in the car. (I don't know if the injectors in the car are exactly the same as the extra ones I have.)

[This message has been edited by Patrick (edited 09-13-2012).]

See Resistors In Parallel Calculator

Note Measuring low ohm is hard many meter and more important meter's lead wires...
and remember resistance in leads, harness, all plugs, etc... 5.7 is close

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[This message has been edited by theogre (edited 09-13-2012).]

quote Originally posted by theogre: Note Measuring low ohm is hard many meter and more important meter's lead wires... and remember resistance in leads, harness, all plugs, etc... 5.7 is close

I thought "close" only counted when throwing horseshoes.

An ideal reading would've been 4.2 ohms on each bank. My reading works out an average of just over 17 ohms per injector. Of course, that's assuming that there isn't one or two injectors with much higher resistance, and one or two with less.

So does this really tell me anything? I should probably just go ahead and remove the top intake plenum so I can access each injector. Then I can individually test their resistance and also apply some voltage to see if they "click".

I'm really kicking myself that I didn't do this earlier when I still had the intake plenum off.

[This message has been edited by Patrick (edited 09-13-2012).]