test the injection wiring

[Momohenri]

Hello everyone, here is my problem with my 1988 Bronco II.
I tested the pressure at the fuel rail shaeder valve and I have 35-36 psi, I have spark at the spark plugs, the code reader in KOEO gives me 21 (Cooling temperature sensor
out of nominal range or ECT probe out of range) and 24 (Intake air temperature sensor(ACT, IAT) or temperature probe
intake (VAT) out of range) but normal since the engine was not running. KOER does not work since the engine does not start
Impossible to start it, the starter turns well but no start.
Any idea would be really appreciated

 

[Brain75]

Any reason why there might be a big underlying issue? - like parked for 3 years and fuel has gone bad.

I'd start by checking the most basic basics, fuel air fire...
clean out the air cleaner box and make sure it is not plugged...
verify the fuel issue is all the way by using some starting fluid to see if it catches and runs for 2 seconds. (rule out bad fuel/clogged injectors/clogged rail after schrader)
then use a spark tester to verify spark.

does it catch and try to start repeatedly, or just crank and crank never catching?

edit, I missed the spark the first time I read it... and by the title you think it is wiring, if electrical is your hunch, my first tool would be a noid light.

 

[Momohenri]

Thank you for your response, as said above I have good fuel pressure on the rail and spark, but I have not tried with start pilot, maybe I will have time later to try that, I would like to know if it is possible to test the injector connectors to see if they have 12v

 

[Brain75]

I think your post was simultaneous as my edit/update... - noid light.
something like this... dunno if you can see this or if amazon will mangle it trying to localize it..

Amazon.com

 

[Momohenri]

no way to test with a multimeter?

 

[Uncle Gump]

The injectors are supplied a constant battery voltage. They are then ground side switched by the ECM to activate and spray fuel.

So testing for power is simple with a DMM. Key ON... DMM should read battery voltage on the injector power wire.

Testing the pulsed ground is commonly tested with a noid light. A DMM is not good for this because the display update rate for the meter is not fast enough to display a usable reading. While a noid light will have a visual flash of a light each time ground is applied.

 

[Momohenri]

thank you, I will try to get a noid light, I will tell you the result

 

[Brain75]

an analog meter might be usable in place of a noid light, but yeah a digital just doesn't react fast enough.

 

[bcschief]

Harbor Freight has Noid Light kits not too pricey.

 

[Cees Klumper]

One easy check also would be to try and start the engine for a bit, then pull spark plug(s) to see whether they are wet or dry. If wet with fuel, then the injector for that cylinder appears to be working. A few years ago my truck from one day to the next would not start. Turned out to be a bad capacitor in the ECU. Replaced both of the capacitors (few $) and it fired right back up.