86 GTV6 Injector problems

[GTV6FLETCH]

Hey all,
Need some help with my Ljet injectors.
Car sat for years , so drained the tank and replaced fuel pump, filter and fuel lines in engine bay aswell as 6 new injectors.
Car starts and runs but has a misfire on cyl 6.
Have checked spark  and have today noticed that the car will only run 5 injectors. I discovered this by disconnecting all the runners and lifting the whole fuel rail and runners up above the heads whilst still connected and resting them on a plastic sheet with a piece of paper. Disconnect the coil and turn over.
I then played around with the injector connectors and have found that 1 to 5 spray, 6 is bad, swap 5 and 6 plugs and 6 will work. If I Disconnect any other cyl no 6 starts to work ?
Have tripple checked all earths, swapped out double relay, swapped ecu . I am now really sick of it , need some advice.

[GTVeloce]

Perhaps the problem is in the wiring loom or plug for inj 6? Does that plug work on any of the other injectors?

[bonno]

Hi GTV6FLETCH
From the basic requirements applicable to internal combustion engines, my guess is that it is electrical, rather than a fuel or compression related issue.  I would check the following in order applicable to # 6 cylinder and make good/replace if faulty (process of elimination)
1.   Resistance value for spark plug lead, it should be the same ohm value as the others.
2.   Faulty spark plug (gap, cracking, fouling etc)
3.   Distributor cap (cracking, lead connection terminal, internal contact signs of wear /corrosion.
If these checks fail to resolve the problem, then further checks are required on the cars electrical system. Find below information on how to test/check spark plug lead.
https://www.instructables.com/How-to-Test-a-Spark-Plug-Wire/

[festy]

I then played around with the injector connectors and have found that 1 to 5 spray, 6 is bad, swap 5 and 6 plugs and 6 will work. If I Disconnect any other cyl no 6 starts to work ?
Have tripple checked all earths, swapped out double relay, swapped ecu . I am now really sick of it , need some advice.

Have you checked the resistance of each injector? You might have a bad one that is drawing too much current.

[bonno]

Hi GTV6FLETCH
In the case of it possibly being a faulty injector, I have attached a useful link on testing for vehicles not incorporating OBD2 diagnostic equipment (old school).  These 3 steps involve listening technique, check for power circuit to injector and check trigger circuit from ecu. 
https://www.wikihow.com/Test-Fuel-Injectors
Hope this helps
cheers
bonno

[festy]

Those tests won't give any useful information in this instance, the injector solenoids need to be checked to see if one has failed and is overloading the driver circuit.

Grab a multimeter, set it to resistance (ohms), unplug each injector and stick the multimeter probes across the two pins on the injector.
L-Jet injectors are oldschool low resistance type, and from memory should have about 3.5 ohms resistance each.
You're checking to see if one has a lower resistance than the others.

[bonno]

Agree, check resistance value for stuck injector(simple check first), however I suggest it won't identify broken or damage power wire to the injector nor a faulty trigger circuit from ecu. The listening technique or resistance check, are simple checks to identify sticky/stuck injector.

[GTV6FLETCH]

cheers for all the suggestions,
I checked resistance on 6 x old injectors and got 3.2 ohms across them all , then checked 6 x new injectors and got 2.6 ohms across all 6 ?
I then got 3 x of the old injectors and on the bench put a few drops of petrol in them and put 30 odd psi of compressed air behind them and touch 12 v from a car batt to them , they seem to click nicely and let the pressure out.
So then threw those 3 old ones in the 1-3 bank and changed out no 6 new with an old one.
Car ran like the biggest heap of Shite .
Pulled the injectors up still attached to fuel rails and turned over with no coil,
number 1 was not closing (so stuck open ) no 2 was not opening and 3 seem to do what an injector is meant to do spray and stop.
Have just finished replacing 1-3 with the 3 x new and put the old no 3 into no 4 and 2x new for 5 and 6.
car seems to be back to the way it was 2 days ago, still got a miss some where ?
Too late now to keep playing with it, will have another look tomorrow arvo.